Using Aluminum Oxide Paint To Secure Wi-Fi

eldavojohn writes "The BBC reports on people using aluminum oxide in their paint to block Wi-Fi signals from leaving their home or business. Aluminum oxide resonates at the same frequency as Wi-Fi signals and other radio waves, blocking data from going outside a building. It's not a flawless solution, as it may also block AM/FM signals. You or your neighbors may be unwittingly using this already, as most pre-finished wood flooring uses aluminum oxide as a protective coating."

Comments

Cellphone reception?

[beef curtains]

Wouldn't keeping radio signals in also have the unfortunately side effect of keeping radio signals out? While having a neighborhood coffee shop offer free wifi to paying customers while being an of oasis of cellphone-free peace & quiet would be sweet, having no cellphone reception at home because one desperately wants to prevent neighbors from stealing one's wifi seems very inconvenient (especially when setting up even the most basic built-in wireless router security would successfully do the trick in 99.9% of cases).

Re:Cellphone reception?

[RobVB]

Wifi works at around 2.4 Ghz, GSM frequencies are between 380 Mhz and 2 Ghz, with the most frequently used frequencies being GSM900 (890-960 Mhz) and GSM1800 (1710-1880 Mhz).

From the article:

The paint contains an aluminium-iron oxide which resonates at the same frequency as wi-fi - or other radio waves - meaning the airborne data is absorbed and blocked.

I assume this means the aluminium-iron oxide resonates at around 2400 Mhz, which shouldn't interfere with normal cell phones.

Re:Cellphone reception?

[Anonymous Coward]

Does this wreck mobile phone signals? My understanding is that phones and wifi are in different parts of the radio spectrum?

Re:Cellphone reception?

[morgan_greywolf]

Try reading more carefully:

FTFA:

While paints blocking lower frequencies have been available for some time, Mr Ohkoshi's technology is the first to absorb frequencies transmitting at 100GHz (gigahertz). Signals carrying a larger amount of data - such as wireless internet - travel at a higher frequency than, for example, FM radio.

...

"Our current mobile phones work at much lower frequencies, around 1.5 gigahertz. But, our material can also absorb frequencies that low, so you could block phone signals from outside and stop people's phones ringing during the movie," he said.

From the sounds of it, just about anything below 100 GHz gets blocked. That means cellphones, too.

Re:Cellphone reception?

[mbone]

They said it, but I have to wonder. Resonant generally means you have a dimension of order a wavelength. The paint particles are much smaller than the wavelength, so it sounds to me as if they are simply building a Faraday Cage, but with metallic paint, not aluminum foil or metal sheeting.

Note, if you are going to do this, you need to avoid holes the size of a wavelength / 4 or bigger - a few cm for WiFi (12 cm waves). If you like windows you should also put a fine wire mesh on them.

Re:Cellphone reception?

[jeffmeden]

So "other radio waves" means "only the rest of the ones at 2.4ghz"? It even states in the summary that it "may block AM/FM signals" which are WAY below anything used by a cellphone. From the sound of the article, they are interested in blocking the widest range possible, with the researcher boasting about blocking all frequencies up to 200 GHz. Add to that the tendency of cellphones to use a LOT less transmit power and reception attenuation than typical Wi-Fi hardware, and it sounds a lot like this would certainly be an issue for cellphones.

Re:Cellphone reception?

[RobVB]

"Our current mobile phones work at much lower frequencies, around 1.5 gigahertz. But, our material can also absorb frequencies that low, so you could block phone signals from outside and stop people's phones ringing during the movie," he said.

They said "can" and "could", not "does" and "will". There might be a switch. Or even different versions, which I guess makes a little more sense.

Re:Cellphone reception?

[PIBM]

And that's called a mosquito screen -- just make sure not to get one in plastic.

Re:Cellphone reception?

[morgan_greywolf]

They said "can" and "could", not "does" and "will". There might be a switch. Or even different versions, which I guess makes a little more sense.

Yeah, that's kinda what I'm on about, just doing it in a roundabout way. I'm no physicist, but it doesn't seem to be that a *single* RF absorbing paint could block everything from 1 Mhz-100 GHz, or even 1.5 GHz - 200 GHz. That's just too many frequencies for something like paint. 1 foot thick lead vault, okay, but paint? Mmmmmm...let's just say I kinda doubt it.

Re:Cellphone reception?

[elashish14]

A conductive metal has free electrons which will block and reflect any waves below its plasma frequency. However, an ionic solid does not have free electrons - instead, it has just a few resonant other mechanisms with limited range so it will block a more specific part of the electromagnetic spectrum than a metal would. The frequency of wifi signals happens to be in the range of one of these mechanisms for the paint used.

Re:Cellphone reception?

[pz]

They said it, but I have to wonder. Resonant generally means you have a dimension of order a wavelength. The paint particles are much smaller than the wavelength, so it sounds to me as if they are simply building a Faraday Cage, but with metallic paint, not aluminum foil or metal sheeting.

Note, if you are going to do this, you need to avoid holes the size of a wavelength / 4 or bigger - a few cm for WiFi (12 cm waves). If you like windows you should also put a fine wire mesh on them.

Funny thing about electromagnetic resonance. The wavelength in vacuum / free air matters only ... in vacuum / free air. The wavelength of a signal in a different medium, with presumably different dielectric constant and impedance will be ... different! Water molecules are famously resonant at 2.45 GHz, that's where microwave ovens operate, despite the vacuum wavelength of 2.45 GHz photons being about 12 cm. The inter- and intra-molecular impedance makes H2O absorb those photons quite well. Water is quite rather opaque at those frequencies, despite being transparent at higher frequencies, say in the visible spectrum, and despite individual H2O molecules being many orders of magnitude smaller than the vacuum wavelength of 2.54 GHz photons.

Futhermore, bear in mind that aluminum oxide is not at all like aluminum. First off, it's an oxide. It's not a metal. It's a quite good insulator, and is used as a common abrasive because of its hardness. With impurities to give it color, it is the primary ingredient in sapphires and rubies. Coating something with aluminum oxide won't create a Faraday cage, but according to the news item, will provide a certain level of frequency-specific shielding.

Re:Cellphone reception?

[Anonymous Coward]

You are no physicist. Metalized paint can form a Faraday Cage. http://en.wikipedia.org/wiki/Faraday_cage

Re:Cellphone reception?

[Geoffrey.landis]

Water molecules are famously resonant at 2.45 GHz, that's where microwave ovens operate,

No, they're not. That's a myth. There's no water resonance at or near 2.45 GHz. Water absorbs at pretty much any microwave frequency, with stronger absorption the higher the frequency.

If anything, you'd want to tune a microwave oven away from strong water resonances, because you want the radiation to penetrate (so as to heat the object evenly) and not be shallowly absorbed, which would result in uneven heating. (Note that a microwave oven is a cavity, so you don't need to absorb energy in a single pass-- it will resonate around until it does get absorbed.).

Re:Cellphone reception?

[Man On Pink Corner]

Funny thing about electromagnetic resonance. The wavelength in vacuum / free air matters only ... in vacuum / free air. The wavelength of a signal in a different medium, with presumably different dielectric constant and impedance will be ... different! Water molecules are famously resonant at 2.45 GHz, that's where microwave ovens operate, despite the vacuum wavelength of 2.45 GHz photons being about 12 cm. The inter- and intra-molecular impedance makes H2O absorb those photons quite well. Water is quite rather opaque at those frequencies, despite being transparent at higher frequencies, say in the visible spectrum, and despite individual H2O molecules being many orders of magnitude smaller than the vacuum wavelength of 2.54 GHz photons.

Helpful hint for posters: if you don't know a damned thing about physics, don't answer questions as if you do.

Helpful hint for moderators: if you don't know a damned thing about physics, don't mod up posts full of word-salad wharrgarbl like "intra-molecular impedance."

http://www.howeverythingworks.org/prints.php?topic=microwave_ovens&page=4

Re:Cellphone reception?

[morgan_greywolf]

Neither are you. A shopping bag lined with foil can act as a Faraday cage as well, but that still doesn't mean it's going to be effective against a wide range of frequencies, and certainly not against signals that are very powerful. From the article you quote:

The effectiveness of a Faraday cage or shield is dependent upon the wavelength of the electric or electromagnetic fields it is intended to shield. Effectiveness of shielding also depends upon the types of metals used in the cages as well as their thicknesses.

This guy in TFA makes it sound as if all I'd have to do to stop a radio station from transmitting is paint their tower with his paint.

Somehow, I doubt that's going to work.

Re:Cellphone reception?

[Forge]

The paint could also provide some much-needed relief during nights out at the cinema.

Our largest local movie theater installed an electronic cellphone signal blocker some years ago. It worked very well and almost put them out of business.

You see people on call (like Sysadmins, Doctors etc...) and people who feel a need to be reached on short notice for personal reasons (parents of small children), no longer saw that theater as an option for dates. This might not be a problem in some places but because of the lower pay scales (and hence higher relative cost of movie tickets) here, those affected were a major proportion of the theater's customer base.

In short they had to turn off the signal blocker and announce to disgruntled customers that it's ok to come back.

I am trying to imagine the dilemma if they had used this Aluminum Oxide paint instead, how much would it cost them to scrape it all off?

Re:Cellphone reception?

[wastedlife]

This is why having a posted "keep cellphones off or vibrate only" rule is much better than active or even passive signal blocking. Granted, there will still be a few assholes that do not follow this, but thats where you exercise your right to kick them out.

IAAFLMTE (I am a former local movie theater employee).

Also, people who try to bring small children into a Rated R feature need to die in a fire. Its not because we care how about shitty of a parent you are, other patrons do not want a screaming kid while they enjoy a film. Save it for Spy Kids 15 </rant>

Re:Cellphone reception?

[pz]

I stand corrected on the water resonance part.

The impedance part, well, perhaps Mr. Pink Corner needs to understand more where resistance comes from. The reason that microwave ovens work at all is that there is a resistive (ie dissipative, lossy, real, call it what you will) component to the impedance of water at those frequencies, dissipating EM energy into heat. Here's a quote from the nicely informative link Mr. Pink Corner provided:

Rather than interacting with the water molecules via a resonance, the microwaves in an oven heat the water by twisting its molecules rapidly back and forth so that they rub against one another. The molecules are heated by the molecular equivalent of sliding or dynamic friction. The choice of 2.45 gigahertz gives the water molecules about the right amount of time to twist in each direction. The precise frequency isn't important, but microwave ovens are required to operate at exactly 2.45 gigahertz so that they don't interfere with communication systems using nearby frequencies.

And here's another clue about physics, Mr. Pink Corner, when you have a complex impedance, like an RC circuit in a lumped model system, the speed of light through those components is determined by the RC time constant. The speed of light is slowed by the reactive portion of the impedance. In that system. Otherwise the movement of the current would not be impeded and the full voltage would appear at the far side of the C element instantaneously. But it does not: the speed of propagation is slowed, as reflected in the time constant. This becomes especially evident when you look at transmission lines and the impedance of the line determines the propagation speed (as well as the line loss due to heating of the real component of the impedance). Same thing in water, except, as I've been corrected, there is no resonance at 2.45 GHz.

Re:Cellphone reception?

[Anonymous Coward]

This guy in TFA makes it sound as if all I'd have to do to stop a radio station from transmitting is paint their tower with his paint.

Painting the tower won't do anything because the tower only supports the antenna. And neither would painting the antenna. You could think of an antenna as a metal antenna with a thin metal paint on it if you want to.

Re:Cellphone reception?

[AndrewNeo]

Someone brought their kid to the opening weekend showing of 300. I'll let you guess which scene the mom ended up taking her child out at (hint: it was early on)

Re:Cellphone reception?

[NeverVotedBush]

Our largest local movie theater installed an electronic cellphone signal blocker some years ago. It worked very well and almost put them out of business.

Was this in the USA? The reason is that doing this, while so very nice to prevent the idiots who don't know how to put their phones on vibrate from bothering everyone else, is also highly illegal.

The reason is that it can interfere with emergency calls even outside the building. The FCC can impose fines on the order of thousands of dollars per day that such a system is active.

There are moves afoot to try to get special exemptions to jam cell phone communications (prisons are another example) but so far it is still very illegal to run a jammer in the USA.

Re:Cellphone reception?

[zippthorne]

You can get them in aluminum or fiberglass. Plastic is not standard.

Re:Cellphone reception?

[Cley Faye]

There is another issue; blocking cellphones also ban emergency calls.
Granted, in a theater there might be other way to call for help, but locking out security for some peace while looking at a movie doesn't sound good to me.

Re:Cellphone reception?

[sunderland56]

The reason is that it can interfere with emergency calls even outside the building.

Actually the primary reason that jammers are illegal is that they are unlicensed. All unlicensed transmitters are illegal in the USA.

There is also a section of the FCC rules that prohibits interference in most cases, and absolutely prohibits willful interference.

Re:Cellphone reception?

[Forge]

The joke of it is that those people who stoped going because of the signal block are also the ones who set the phone to vibrate, then when called, mumble and listen or run outside to talk.

When I mentioned parents of small kids, I'm talking about people who leave the kids at home and can't bare to have the babysitter unable to call in an emergency (Where do I put use diapers again?)

Re:Cellphone reception?

[Forge]

This did not happen in the US but in Jamaica. Our rules are somewhat different. I.e. One of our maximum security prisons also installed a Jammer. It created problems for people living close to the prison and for people passing on the highway in front of the prison.

They were compelled to turn it off ontil they could contain the signal. within the walls. This fancy paint might actualy help them. I realy don't know how the open "play area" between the outer walls and the cell block will affect this. (That area is rather large and includes a Cricket Field.)

Re:Cellphone reception?

[Anonymous Coward]

Jammers are also illegal in the UK, and due to "pirate radio" ships in the 1960s, *outside* the UK also if the navy can be bothered to board you and the signal reaches the UK :-)

They never tried that with the soviet "woodpecker" interference though, more's the pity...

Re:Cellphone reception?

[Intron]

So they should also let you bring your gun in case of terrorist attack? And your pit bull in case you are threatened by a pack of wolves?

Re:Cellphone reception?

[Anonymous Coward]

Until someone blows their nuts off accidentally with a mobile phone, I'll file your strawman under "wildly disproportionate overreaction."

Re:Cellphone reception?

[insertwackynamehere]

Obviously, you haven't been reading about the dangers of cellphone radiation when in proximity to the male genitalia and reproductive organs

Re:Cellphone reception?

[Man On Pink Corner]

Pro tip: Stop digging.

Re:Cellphone reception?

[Anonymous Coward]

In short they had to turn off the signal blocker and announce to disgruntled customers that it's ok to come back.

I am trying to imagine the dilemma if they had used this Aluminum Oxide paint instead, how much would it cost them to scrape it all off?

Nothing, because the mistake was telling people they were blocking it. Had they simply shrugged and said "Hell, we don't know why you can't get signal, must be how it was built or something" then most people simply wouldn't care. Or take it as an opportunity to get some on-call pay without actually getting called. But when you tell people you're doing it on purpose it pisses them off and they quit coming.

Re:Cellphone reception?

[wastedlife]

Those people were removed from the theater by me or one of the other staff. Although that still creates the problem of those customers not coming back.

Sorry, the thing about small kids was an angry rant brought upon by me remembering my days as an AM at the local theater.

Re:Cellphone reception?

[Anonymous Coward]

You already lost your credibility in this post with the first fabrication, Geraldo, so you might as well give up. No one's going to tune in to watch you open Al Capone's other vault.

Re:Cellphone reception?

[Rob the Bold]

From the sounds of it, just about anything below 100 GHz gets blocked. That means cellphones, too.

I have Aluminum siding, and while an alloy rather than a compound, it is effective for blocking GSM and WiFi. I suspect it's probably better, since the idea of the paint is to create a more cost-effective and easier to implement solution than plating a room or whole building. I've got to stand near an unscreened window to make a call. Anyway, it suggests that the range of applications for this paint technology would be rather limited, say to institutions that use mobile computers indoors (and are security freaks) but who don't use mobile telephones.

Re:Cellphone reception?

[master5o1]

Excellent. I can finally discard my tinfoil hat for a much more widely accepted solution of having a suitably coloured house.

Re:Cellphone reception?

[scottv67]

>Someone brought their kid to the opening weekend showing of 300. I'll let you guess which scene the mom ended up taking her child out at (hint: it was early on)

"This will not be over quickly. You will not enjoy this. I'm not your King."

Re:Cellphone reception?

[Anonymous Coward]

Wildly disproportionate is "I have to have my cellphone on in the movie theater in case there is an emergency that nobody else can handle". How many such calls have you gotten in your entire life? Didn't think so.

Re:Cellphone reception?

[Hognoxious]

You see people on call (like Sysadmins, Doctors etc...)

It's indeed lucky that mobile phones were invented before medical science.

Just imagine if doctors had been round in the old days, there'd have been no way to contact them in a hurry!

Re:Cellphone reception?

[fluffy99]

All unlicensed transmitters are illegal in the USA.

Funny you should quote FCC rules about deliberate interference, yet make the claim that all transmitters need to be licensed. In general you do not need to license for certain frequency ranges when below the power threshhold (typically 1 watt).

Re:Cellphone reception?

[BitterOak]

Was this in the USA? The reason is that doing this, while so very nice to prevent the idiots who don't know how to put their phones on vibrate from bothering everyone else, is also highly illegal.

I think you are confusing active vs. passive blocking. Active blocking is illegal as it involves transmitting signals on the same frequencies as are used by cellphones, and this is regulated spectrum. Passive blocking, by using special paints or metal screens is perfectly legal.

Re:Cellphone reception?

[Idbar]

I'm guessing spotting a prisoner using a cellphone in an open area would be a bit easier than indoors.

On the other hand, I would believe that in general any RF device can be attached to an antenna to provide gain and direction. Isn't possible to have the Jammer high up and aim it down right to the middle of the field using a fairly good antenna?

Re:Cellphone reception?

[Rising Ape]

I've never heard of anyone try to explain microwave heating in those terms before, perhaps because it doesn't really explain anything and confuses more than enlightens by bombarding the reader with unintuitive abstractions. There's no current involved for a start, unlike an RC circuit. Impedance here would refer to the ratio between electric and magnetic fields.

The loss mechanism is indeed as Man on Pink Corner described, interaction of polar water molecules with the electric field. The slowdown of microwaves travelling through the medium is due to absorption and re-emission in the medium, but the re-emission has a delay and hence a phase difference. The superposition of waves that results produces a wave pattern equivalent to one travelling at a slower speed.

Re:Cellphone reception?

[Roland Deschene]

... or a CB, which can be up to four watts

Re:Cellphone reception?

[Idbar]

Cellphone operating frequencies are licensed and paid for. Reason why a Jammer wouldn't be illegal.

On the other hand non-licensed frequencies require to keep their transmission power below certain level. However, that means that if you want to block people using your wireless you shouldn't be able to interfere people using their wireless, which makes the Jammer useless (unless of course you want to jam your own wireless, which would be, well, silly).

If it were the case where emergency calls cannot be blocked, then I guess paint would be illegal too.

Re:Cellphone reception?

[Anonymous Coward]

If the thing's on vibrate and I walk outside to answer it, why should you care?

Re:Cellphone reception?

[Anonymous Coward]

Because almost no one puts the fucking thing on vibrate!

Re:Cellphone reception?

[Swampash]

Dude. Just... wow. Let me guess, you use Monster cables exclusively, right?

Re:Cellphone reception?

[Lumpy]

yes it does. This "special" paint has been available for years now at home depot. But instead of aluminum it's iron. It's "magnetic paint" for making kids walls allow magnets to stick. three coats of this stuff in a room and it's dead except for the windows. (Paint the door and jamb too) aluminum screens and storm windows turns the room into a faraday cage. close the door and wifi in the house disappears, cellphone coverage in the room is 0 bars..

http://www.rustoleum.com/CBGProduct.asp?pid=127

Glad to see the BBC is way behind the times on this.

Re:Cellphone reception?

[Anonymous Coward]

It is not illegal if I passively block cellphone signals. Most theaters are built with steel roofs which block RF, add in some simple aluminum screen on the walls behind the curtains and I can block everything LEGALLY. and this is what many do. The 2 new theaters around here are built that way, walk into the Imax seating area and signal goes from 5 bars to no service. They are doing gangbusters, they are proud of the "we block all cellphones" sign at every theater entrance. the sign warns that your cellphone will not work beyond this point.

They are doing great, so it seems that some areas embrace cellphone blocking. Doctors can go watch a movie in their home theater. Most dont want to be in large rooms of us Icky poor people anyways.

Re:Cellphone reception?

[imhennessy]

GP was posting about an active Jammer.

ivan

Re:Cellphone reception?

[cyn1c77]

You see people on call (like Sysadmins, Doctors etc...) and people who feel a need to be reached on short notice for personal reasons (parents of small children), no longer saw that theater as an option for dates. This might not be a problem in some places but because of the lower pay scales (and hence higher relative cost of movie tickets) here, those affected were a major proportion of the theater's customer base.

Remember before cell phones? You could watch a whole movie in the theater without interruption? Your 3 year old was with the teenage babysitter, and if they both died or your house burned down, you wouldn't know until you got back home. Sysadmins didn't go to the movies because they would have gotten their asses kicked, and doctors were so fucking rich that they just bought the new releases and watched them at home when they were on call.

Yet somehow everything worked out just fine. If there was an emergency, you had to call the theater and have the attendant go and find the person you wanted to talk to. But that was for real life-or-death emergencies... if you were on call, you weren't at the movies, you were sleeping at the hospital or inside the mainframe.

Ah, the good old days... when it wasn't socially acceptable to be a self-important dipshit with a cell phone.

Re:Cellphone reception?

[Sulphur]

When doctors are tired of doing rounds; can they do squares?

--

Have you ever held a door for someone, and had them go through and pull it shut.

Re:Cellphone reception?

[Anonymous Coward]

The response was clearly to a post about active (the word electronic is used) blocking. So above comment is quite redundant.

Re:Cellphone reception?

[RockDoctor]

I am trying to imagine the dilemma if they had used this Aluminum Oxide paint instead, how much would it cost them to scrape it all off?

Three points :
1) how much would they have to scrape off? Possibly only one (outside) wall to allow the radiation to penetrate into the chamber.
2) If this material worked (and I'm pretty dubious of the physics claims - significant attenuation between 100-odd GHz and 0 GHz, a range of 10^11 in frequency. Bit optimistic there.) , then you wouldn't necessarily need to paint the inside of the walls, just the outsides, where there are often service corridors, office spaces, staff changing rooms, store rooms, etc.
3) What even-ness of coverage would you need. To a first approximation, one wavelength should provide shielding (or at least attenuation), and for 2.4*10^11 Hz, that's 1.25m ; so, a single-doorway wouldn't necessarily allow radiation in (or out), but a double-doorway would likely. Also, a large window (in a domestic situation), would probably stop it working as a screen. Not good. Correspondingly, the process of removing externally-applied paint would only need to proceed a room at a time - this store-room, then that office - until there's sufficient signal in the auditorium.

Obviously, you could try applying the paint to external walls as-and-when they become available for re-painting (if they ever got painted ; why would you paint a wall that only staff will see?) and using a phone as a signal-strength meter until it decayed to the point of being unusable. Better - if you can arrange the pattern appropriately, only allow sufficient signal to illuminate the aisles.

Re:Cellphone reception?

[cerberusss]

One of our maximum security prisons [...] includes a Cricket Field.

I do not care what crime you've committed, that is an inhumane and utterly cruel punishment.

Re:Cellphone reception?

[Anonymous Coward]

If the thing's on vibrate and I walk outside to answer it, why should you care?

... because you don't. You answer it inside, say "hold on a minute", stand up in the middle of the theatre to walk out, taking others out of the moment of the movie. You ruin any vested emotion those around you have sunk into the film, robbing them of the joy felt when experiencing a particularly moving scene for the first time. And you kick puppies.

Re:Cellphone reception?

[Anonymous Coward]

A switch? In the paint? How?

Re:Cellphone reception?

[Jared555]

Simple solution, use a cell phone repeater and if there are any other signals you actually want (TV, radio, etc.) put the antenna on the outside of the house.

Re:Cellphone reception?

[Jared555]

Define small children. I watched R rated movies from a young age and it never really affected me much other than a slightly increased fear of the dark*. The main thing is parents need to realize what specific movies are ok and which aren't (I mean some older PG13 movies are now considered R rated) and what their children can handle.

*If anyone wants instructions on how to build a 100kW floodlight array with redundant backup generators please let me know and I will send you the plans for mine.

Re:Cellphone reception?

[sunderland56]

Certain bands and frequencies fall under a "default" license - such as garage door openers, walkie-talkies, and 802.11 wifi. You don't need to apply for a license to transmit or receive on these frequencies, but you are subject to the FCC rules and regulations. That's why you can't boost your wifi output to 1,000 watts, for instance.

Re:Cellphone reception?

[marhar]

if you don't know a damned thing about physics, don't mod up posts full of word-salad wharrgarbl like "intra-molecular impedance."

Oh great, another intra-molecular impedance denier!

Re:Cellphone reception?

[Forge]

That doesn't work when senior Engineers from BOTH major cellphone companies gather in the lobby to cuss a blue streak and make demands during intermission.

Re:Cellphone reception?

[fluffy99]

There is no such things as a "default license". FCC uses the terms "licensed frequencies" which require an FCC license or operators permit to use, and "unlicensed frequencies" which do not require a license or special permission. Note that manufacturers may have to apply for and maintain the licensing for certain devices such as cell phones. You are correct that you still need to adhere to FCC rules regarding power and operation while using the unlicensed spectrum.

Re:Cellphone reception?

[wastedlife]

Our rule was that children under 6 were not allowed in 'R' movies. No exceptions. Not sure what you mean by older PG13 movies now being considered R rated? I thought the rules had relaxed a little and PG13 movies could have more swearing and violence than previously. Then again, it seems they are more prudish about sexual content so that might be what you are referring to.

Re:Cellphone reception?

[Hurricane78]

So after cat salad and hello cthulhu, now there's word salad and wharrgarbl too?

Man, where would we be without the Internet...

Extra protection?

[BadAnalogyGuy]

I'm already using aluminum foil lining in many of my hats and clothes to protect me from the government transmissions. However, I hadn't heard that Al2O3 was any better than straight aluminum foil.

It seems suspicious that this story would be posted immediately after I began considering papering my walls with foil.

Re:Extra protection?

[ColdWetDog]

May not be better but it could be more, how shall we say, stylish. Maybe quieter as well. I do like his pandering to the 'think of the children' racket.

"We're assuming that excessive exposure could be bad for us. Therefore we're trying to make protective clothes for young children or pregnant women to help protect their bodies from such waves."

Give me a break. Next think he'll be trying to create is an Aluminum oxide / silver dip - keep away nasty radio waves and germs, all in one toxic package.

I think this guy is mostly looking for some investors.

Re:Extra protection?

[Anonymous Coward]

You know that they tell you to use aluminum foil hats to INCREASE the effect of radio waves on your brain. The result is that you get paranoid enough to look in the wrong places for THEM.

Re:Extra protection?

[Abstrackt]

You might want to read this article on the effectiveness of foil helmets. ;)

Re:Extra protection?

[MozeeToby]

If I were a science teacher, I think I would have a weekly contest "What's wrong with this?". I'd give all the kids a website, newspaper article, creationist newsletter (probably lose my job over that one but oh well), etc... and have them come up with a list of all the reasons that it is nonsense. Start with easy stuff (like the difference between EM and Ionizing radiation) and move to more challanging things later (like what a valid sample size is). We need to expose kids to the idea that not everything they read is gospel, to think critically about what they read and see and actually apply their education.

Re:Extra protection?

[Anonymous Coward]

foot thick lead helmets?

Re:Extra protection?

[LordNimon]

Since you seem to know so much about it, why not create a web site that does just this? Even if school teachers can't do it, enterprising parents would probably like to use your site as additional education.

There's an idea for a startup - a company that creates additional homework for parents to give their children to make up for deficiencies in what their school teaches them.

Re:Extra protection?

[ArsonSmith]

"I wish I had a cross made of kryptonite. Because then I could kill Dracula and Supperman."

-Jack Handy

Re:Extra protection?

[ArsonSmith]

Maybe you could have like a 3rd party wiki addon for browsers that would allow you to add comments to pages, independent of the page itself. You could then browse other peoples comments as well.

Re:Extra protection?

[AndrewNeo]

No, not Supperman! He brings me my dinner!

Re:Extra protection?

[PotatoFarmer]

Ah yes, the elusive Supperman. I was very unhappy when Marvel finally decided to have him killed off by his arch-nemesis Bulimiax.

I still cherish my pristine copy of Supperman #103, in which he manages to incapacitate the entire Third Reich by making them fall asleep after a huge turkey dinner.

Re:Extra protection?

[Anonymous Coward]

I'm not sure anyone who quotes MSNBC is a good authority on what constitutes "nonsense".

Re:Extra protection?

[maxwell demon]

"I wish I had a cross made of kryptonite. Because then I could kill Dracula and Supperman."

-Jack Handy

And what do you need to kill Lunchman? :-)

Re:Extra protection?

[bertoelcon]

My AP Physics teacher had us do an assignment like this once a semester where we had to find 1 story where the facts do not add up to the conclusions given, but it had to relate to the topics we covered already.

Re:Extra protection?

[Anonymous Coward]

I'm already using aluminum foil lining in many of my hats and clothes to protect me from the government transmissions. However, I hadn't heard that Al2O3 was any better than straight aluminum foil.

It seems suspicious that this story would be posted immediately after I began considering papering my walls with foil.

I see that they tricked you. Aluminum foil does not work. To truly protect yourself you need to wear a tin foil hat. That is why the government secretly banned tin foil and all you can find in the store is aluminum. It doesn't work!!!

Re:Extra protection?

[Arthur Grumbine]

Ah yes, the elusive Supperman. I was very unhappy when Marvel finally decided to have him killed off by his arch-nemesis Bulimiax.

Now that was brutal ending for a superhero - he was literally chewed up and spit back out.

Re:Extra protection?

[Anonymous Coward]

I'm not sure anyone who quotes MSNBC is a good authority on what constitutes "nonsense".

Its a lot better than Fox News, that's for sure!

Re:Extra protection?

[Rob the Bold]

I'm already using aluminum foil lining in many of my hats and clothes to protect me from the government transmissions. However, I hadn't heard that Al2O3 was any better than straight aluminum foil.

It seems suspicious that this story would be posted immediately after I began considering papering my walls with foil.

I doubt better. Probably just more practical and economical. Consider how much faster you could mind-control-proof your clothing if you could spray on a coating rather than plating it or beating it on. And if you could impregnate polyester or some other fiber with it, you could do it right at the cloth mill. Of course, paint is also easier to apply than aluminum siding.

But I still think their idea is stupid. A spinoff for government transmission blocking though might be just what the doctor ordered.

Re:Extra protection?

[Rob the Bold]

May not be better but it could be more, how shall we say, stylish.

You callin' my aluminum siding unfashionable? It's space-age, man!

Re:Extra protection?

[Anonymous Coward]

Make your helmet out of rubies and sapphires instead (both are made of Al2O3). In fact you might as well wear a crown and carry a scepter.

Re:Extra protection?

[Kaboom13]

No major school system would ever allow this. If you teach them not to believe everything you read, the next step is they don't believe everything they are told. If they don't believe everything they are told, they don't assume their teachers and administrators are correct, and should automatically be listened to and obeyed. As the average modern American school has nothing to do with educating, and everything to do with babysitting, it would be very dangerous to the comfortable low expectations their students and the student's parent's have.

Re:Extra protection?

[HiThere]

You're in luck!

Aluminum oxidizes easily, so aluminum foil quickly becomes evenly covered by a thin layer of aluminum oxide!

So unless the particle size matters...

Re:Extra protection?

[paradxum]

I honestly wish we had a teacher like that in our district... Although you may have detractors, you would also have supporters....

Re:Extra protection?

[Hognoxious]

Even Fox News think so.

Re:Extra protection?

[Chris Burke]

Now that was brutal ending for a superhero - he was literally chewed up and spit back out.

But you have to admit it was a fitting end to the story arc that began when Supperman refused to save Bulimiax's adopted daughter, Anna Rexia, after she overused her power trying to starve a whole middle school. Dying, she promised she'd renounce her evil ways if he only gave her a bite of supper! Sure he may have had a point when he said she was lying and would never truly change, but finishing her off with "And you're fat!" was really uncalled for.

Another victim of the "dark anti-hero" trend of the 80s/90s.

Re:Extra protection?

[Chris Burke]

As the average modern American school has nothing to do with educating, and everything to do with babysitting, it would be very dangerous to the comfortable low expectations their students and the student's parent's have.

One of the scariest books I've ever read was Michael Foucault's Discipline and Punish. It's about the development of the French prison system, and how the principles developed to cow prisoners into obedience were later adapted to the educational system. Not in an abstract or tangential sense, but in a direct literal "Hey those ideas sound like they'd work great for our schools!" sense.

Re:Extra protection?

[fast turtle]

Infidel! You can't teach children to think. That's completely against the law and it means the loss of your consumer privileges for the foreseeable future.

Re:Extra protection?

[babyrat]

It seems even more suspicious that you are 'paper'ing your walls with foil. That is no more likely than you foiling your walls with paper.

Clearly you are a government spy here to...well I'm not sure what, but I am sure it is nefarious.

Re:Extra protection?

[pbhj]

Well I lol-ed, very SMBC.

Re:Extra protection?

[D-Killer]

All of a sudden I see chainmail coming back into fashion!

Finally!!

[Ludedude]

...a way to stop wearing this itchy tinfoil hat!

Re:Finally!!

[jennyfever]

Exactly! I can just wallpaper my house with aluminum foil. Free mirrors AND I get to stop those freeloading hippies next door!

Re:Finally!!

[stokessd]

You need to make your hat out of sandpaper, the dark colored kind that is aluminum oxide. I'd recommend a fine grit unless you want the mellow exfoliating effect of 80 grit on your cranium.

Sheldon

Re:Finally!!

[Ludedude]

A good fashion tip. I hear aluminum oxide is the new black ;)

Re:Finally!!

[Gilmoure]

Paint your bald spot?

Re:Finally!!

[K. S. Kyosuke]

So astronomers will now have to look out for aluminium oxide holes? I guess that makes their task easier...

Re:Finally!!

[budgenator]

The sheathing on my house is aluminized and getting a cell phone signal is very hit or miss either inside the house or in it's RF shadow outside.

Resonance at other frequencies?

[acrobg]

So I get that Aluminum Oxide paint is resonant at 2.4GHz. What about in the 900MHz band, or 1.2GHz band? What frequencies are not resonant in Aouminum Oxide paint?

Re:Resonance at other frequencies?

[John Hasler]

> What frequencies are not resonant in Aouminum Oxide paint?

The reporter is just yammering. He hasn't the foggiest idea what the word "resonant" means and knows less than nothing about radio. All we can glean from this is that someone has put out a press release about rf absorbant paint, something that has been around for decades.

Re:Resonance at other frequencies?

[Anonymous Coward]

All we can glean from this is that someone has put out a press release about rf absorbant paint, something that has been around for decades.

Using information in the article I was able to find the actual science paper. It turns out they are able to tune the resonate frequency of this paint. Very cool. However, the it doesn't go all the way down to 2.4 GHz. That's a pretty long wavelength for this process.

"By coating an entire room..."

[Anonymous Coward]

Wouldn't you have to paint over the windows?

Re:"By coating an entire room..."

[Anonymous Coward]

but I run linux.

Re:"By coating an entire room..."

[M8e]

You could use a fine metal mesh instead of paint for the windows.

Re:"By coating an entire room..."

[sconeu]

Aluminum siding!

Re:"By coating an entire room..."

[SleepingWaterBear]

Even with gaps in the coverage, blocking most of the radio waves should be enough to massively diminish the reception outside the room. Given the already limited range of most wifi transmitters, a few gaps in the paint for windows shouldn't be enough to allow any practical use of the wifi signal from outside.

Now, if you're putting the paint up for security reasons the windows might constitute a real risk, but trying to restrict the range of your wifi transmissions is probably not the best approach to security anyway.

Re:"By coating an entire room..."

[rossdee]

Obvious answer: Transparent aluminum. Its a lot stronger than glass, so you have less to worry about with storms.

Re:"By coating an entire room..."

[Anonymous Coward]

Obvious answer: Transparent aluminum

Also known as sapphire or ruby, but that is still a bit expensive to make windows out of.

Re:"By coating an entire room..."

[Abreu]

Mosquito mesh?

Re:"By coating an entire room..."

[Rob the Bold]

You could use a fine metal mesh instead of paint for the windows.

You may be on to something there. Might be additional benefits too, like keeping insects and vermin out but allowing fresh air in.

Re:"By coating an entire room..."

[HiThere]

You just replace them with transparent aluminum.

Re:"By coating an entire room..."

[Hognoxious]

Unfunny and wrong. Epic fail.

Re:"By coating an entire room..."

[Anonymous Coward]

Epic Fail yourself:

"Sapphire (Greek: sappheiros) refers to gem varieties of the mineral corundum, an aluminium oxide (α-Al2O3), when it is a color other than red, in which case the gem would instead be a ruby."

Re:"By coating an entire room..."

[rdnetto]

Actually, no. Transparent aluminium is different, but given the amount of power it would take to maintain it in that state, hiring a dedicated team of ninjas to kill anyone using a wireless device would be cheaper.

Re:"By coating an entire room..."

[Hurricane78]

For that, there is transparent aluminium!

Unfortunately it's only useful for superheroes with X-ray vision.

Hey, it's good enough for the office...

[d474]

I dipped my head in this aluminum oxide paint, and it keeps all their signals out. Granted, I look somewhat like a cyborg now, but this stuff should work just fine for an office trying to keep their signals in.

Re:Hey, it's good enough for the office...

[Anonymous Monkey]

Looking like a cyborg is good, because the other cyborgs won't try to assimilate you. However, it is important to have a radio transmitter with you everyplace so that you are broadcasting some sort of radio signal at all times. Now, at home, it is still better to line your walls with aluminum foil, but you need to do so INSIDE the walls, behind the drywall, because you don't want the government drones seeing it. You should line your attic as well, but not your basement, because The Worms are attracted to foil. In your basement you should use lots and lots of crushed cans. Sprite cans works best.

Re:Hey, it's good enough for the office...

[Linker3000]

So that's what Tribett was up to!

http://www.flickr.com/photos/43492742@N00/352574903/

Re:Hey, it's good enough for the office...

[Anonymous Coward]

Thank god, I did this when I built my house 14 years ago!

Re:Hey, it's good enough for the office...

[ciaohound]

Thanks for the tip, Buddy Ebsen.

Re:Hey, it's good enough for the office...

[jonbryce]

What you need to be really careful about is the cops in helicopters doing thermal imaging of roofs. They do this to find people running cannabis farms. If you are releasing a lot more heat than normal, then expect a dawn raid. Also, if they don't see any heat being released, expect a dawn raid because they will think you are trying to shield it.

Re:Hey, it's good enough for the office...

[Anonymous Monkey]

Oh, I've got that covered. Copper pipes in the walls, outside of my shielding, are used for heat transfer. I can make my home look thermally normal despite the fact that I house a fusion generator. Obviously it is in one of the lower sub basements, and above the sprite cans.

Re:Hey, it's good enough for the office...

[Anonymous Monkey]

Never build your own house, because they will be able to check records for permits and know your house is custom and then know to check for radio shielding. It is better to buy something run down and let it stay that way, while living in another house in another state. I may have said too much.

Re:Hey, it's good enough for the office...

[Anonymous Coward]

Will they really raid you because your house is well insulated against heat loss? I do find that hard to believe. I should hope that will look for more evidence before proceeding, and I'd also hope that a judge would require more evidence as well before issuing the warrant.

Note: AlFeO *not* Al2O3

[Anonymous Coward]

Note, the material concerned is Aluminium IRON oxide. Big difference. Aluminium oxide is a good dielectric and would be bugger all use for RF shielding. Oh and the article is a wierd too: it talks about 100GHz shielding where WiFi bands are ~ 2.5GHz.

Re:Note: AlFeO *not* Al2O3

[fuzzyfuzzyfungus]

Unless this stuff is very much unlike a certain other aluminum iron oxide composition, there might be a certain other big difference...

Re:Note: AlFeO *not* Al2O3

[mrstrano]

The real question is, why?

There is cryptography for that. Now, apart from the unfortunate and deprecated WEP protocol, there are some really secure alternatives out there, like WPA2.
Certainly more secure than a leaky insulation.
It would be like sending a secure mail over in a physical vault, rather than using PGP or GPG. Who would do that?

Re:Note: AlFeO *not* Al2O3

[BrokenHalo]

Don't knock it - self-illuminating houses (even if only for milliseconds) are the in thing in the new energy-concious world. ;-)

Re:Note: AlFeO *not* Al2O3

[Klaatuu]

Note, the material concerned is Aluminium IRON oxide. Big difference. Aluminium oxide is a good dielectric and would be bugger all use for RF shielding. Oh and the article is a wierd too: it talks about 100GHz shielding where WiFi bands are ~ 2.5GHz.

Thank you for the iron clarification. You see, my wall are encrusted with sapphires, which we all know is crystallized aluminum oxide, and my wi-fi has been leaking like crazy, so I knew there was something fishy in the title.

Re:Note: AlFeO *not* Al2O3

[jhol13]

I thought the same, but then I concluded that the wifi will be REALLY secure after exposure to that. And a bit of magnesium.

Re:Note: AlFeO *not* Al2O3

[Anonymous Coward]

yes, there is a big difference, one of the many recipes for thermite has aluminum mixed with iron oxide. That is not the same thing as a chemical with three atoms bound together of aluminum, iron and oxygen.

Re:Note: AlFeO *not* Al2O3

[Hognoxious]

Well thanks for pointing that out, I'm sure none of us (espicially the GP) knew that. Cockarse.

Re:Note: AlFeO *not* Al2O3

[hjf]

http://en.wikipedia.org/wiki/TEMPEST

Re:Note: AlFeO *not* Al2O3

[Anonymous Coward]

I think we've just solved the Hindenburg mystery: The free Wifi in first class.

Re:Note: AlFeO *not* Al2O3

[Anonymous Coward]

That sounds like the recipe for Thermite... I'm not painting my walls with that stuff. No freakin way!!!

Rebound?

[Rhaban]

So if this paint resonate with wifi signal frequencies, does the signal rebound on it, increasing risks of getting cancer and/or global warming in your own home?

Re:Rebound?

[Lumpy]

Yes and it kills puppies too.

In fact using WPA or WEP or any type of encryption also increases cancer, only open access points are safe.

God I hope you dont use ssh, you'll never have any kids if exposed to that over wifi.

But Why?

[quatin]

Lock your WiFi? I prefer to unlock my WiFi. Stick it to the cable companies!

Re:But Why?

[hodet]

That way when I hit my 30gig cap the whole community can enjoy dialup speeds. Sweet, that'll show'em.

Re:But Why?

[conureman]

I have a tenant in one of my houses who's trying to figure out how to get good enough QOS from the neighbor's unsecured WiFis (seven routers from a 5db antenna) so that he can drop his phone service. I haven't had the heart to tell him it's illegal.

Re:But Why?

[quatin]

I am already enjoying dialup speeds with my awesome 50kbps average upload speed from my high speed cable from Comcast. Good luck getting your 30 gig cap with that.

Does not resonate with me

[Ancient_Hacker]

Dunno where they got the crap about "resonates".

The paint might act as an electrostatic shield, or as a lossy dielectric, both effects that will attenuate RF signals.

  But resonate, no.

Re:Does not resonate with me

[_avs_007]

Seriously... I work with a WiFi lab at work... I have a Faraday Cage in our lab... One of the techs forgot to install an optical isolator on the network cables, so for a few days the ethernet cables went right into the cage... Well, first day I went to use it, I locked myself in the cage, and was surprised that my cellphone started ringing... Without the optical isolators on the network cable, the RF signals were able to find there way into the faraday cage through the ethernet cables....

with that being said, I highly doubt that simply painting your walls will keep RF signals at bay... Even when the grounding wire was simply loose on the door to the faraday cage, RF signals would leak in...

Re:Does not resonate with me

[quatin]

So you went inside a Faraday Cage with an unprotected ethernet cable and managed to get cell phone reception. I on the other hand, can't get cell phone reception if I stand too close to my filing cabinet. I either need to switch to your provider or you need to come do your WiFi experiments next to my filing cabinet.

Re:Does not resonate with me

[afxgrin]

I take it you were using fiber optic cables into the Faraday Cage, so that you weren't adding electrical noise inside?

Otherwise it sounds like you're trying to put a device for protecting optical transmitting equipment from return losses on an ethernet cable.

Re:Does not resonate with me

[elashish14]

Ionic materials can be polarized to interact with electromagnetic waves to block signal transmission. They have a number of absorptive mechanisms. The highest frequency absorption mechanism is where electrons around the nucleus resonate, roughly at 10^17 Hz. Then there's atomic vibrations where the nuclei themselves vibrate (10^14 Hz I think). Not sure what they are for the material used in particular though, but ionic materials can resonate. It doesn't seem that they're in the range used for this application

Re:Does not resonate with me

[MozeeToby]

This article is full of nonsense, it's not even worth the read. For example...

Movie pictures are beamed on the screen by the projector at the back of the cinema. But in the future, you could use a data link that works with millimetre waves.

What. The. Fuck. is that supposed to mean?

Re:Does not resonate with me

[Rick17JJ]

What are they planning to do about the keeping the signals from getting through the windows? Are they going to install screens on the windows which will block those frequencies? Are they going to paint the curtains? Are they going to install interior or exterior shutters, and then paint them too with the anti-WiFi paint which contains aluminium-iron oxide.

I am not an expert, but it seems to me that they would need careful attention to details such as those, to adequately block the signals. For example, I know someone who was recently able to use a campground's free WiFi from withing his old aluminum Airstream trailer. My guess was that the signal was coming in through the window, or possibly through the floor.

However, even if the blocking of signals is not perfect, the anti-WiFi paint might be useful, if that is only one of several other protection measures that are being used. That would especially be true if someone has is parked out front and is using a directional yagi or other type of antenna, hidden in something like a Pringles can. For instance, they probably still should use WPA or WPA2 with a sufficiently long and random password that also includes numbers and punctuation. It would be best to also change the well know default password on the wireless.

Re:Does not resonate with me

[Cyner]

There's only 1 way to complete protect a wireless network: Turn it off.

Everything else is just a layer to help protect it, paint addatives included.

Re:Does not resonate with me

[Skuld-Chan]

Conversely my brother in law works at a wireless lab where they have a copper clad cage, and when he closed the door my cellphone lost its network signal within a few seconds.

Strangely enough the government transmissions didn't stop infiltrating my brain :(.

Re:Does not resonate with me

[Anonymous Coward]

What they are probably talking about when they say resonate is that the individual molecules resonate, just like water molecules in a microwave oven. What they are creating is a lossy paint. I have my doubts that it is really resonant over the entire range (DC-100GHz) though I am fairly sure that it would block all signals in the 380-750nm range.

Re:Does not resonate with me

[zippthorne]

Everyone will still go to the movie theater, but they'll watch the film on their iPhones. They will be confused when the "turn off your annoying cellphones (psst: you can buy annoying cell phones from AT&T)" message comes on, though.

Re:Does not resonate with me

[Gilmoure]

Plug your filing cabinet in to your router?

Re:Does not resonate with me

[BrokenHalo]

There's only 1 way to complete protect a wireless network: Turn it off.

I have a better way, though it does have its downsides: Living a long way away from any roads or other settlements. But I guess there aren't too many places we can do that any more. I am fortunate enough to have a property in deepest, darkest Tasmania where my access road is 1.5 km away from a "C" road. I don't have much problem with wardrivers.

However, it's a long drive on my tractor to drop off my rubbish and pick up my snail-mail... :-)

Re:Does not resonate with me

[yurtinus]

I'm no EE or RF guy, so I don't know how far off base this is-- but aren't Ethernet interfaces typically transistor coupled on either end so you don't have an actual phsyical grounding on either side? I'm guessing the optical isolator is supposed to sit at the edge of the cage itself so you don't have an Ethernet cable antenna going out... ?

I'm still a bit skeptical as I've worked in EMI hardened facilities where we have solid wires leaving the structure to outside antennas and it's really not possible to get a cell signal with the door closed.

Disclaimers--
1) I'm what happens when you let a software guy look at too many circuit diagrams :)
2) Cell provider is Sprint, so I'm suprised when my phone rings in my garage at home...

Re:Does not resonate with me

[Gilmoure]

Make the windows out of Aluminium Oxide as well? Al2O3 is transparent.

Re:Does not resonate with me

[Anonymous Coward]

You took your *active* cellphone into a faraday cage used to shield your experiments from RF.... isn't that a bit self-defeating?

Re:Does not resonate with me

[_avs_007]

Yes, the optical isolator is at the edge of the cage. Cell signal could have been exceptionally strong, because our building has a bunch of repeaters in the ceilings, as well as a bouncer in the main courtyard.

Re:Does not resonate with me

[_avs_007]

The experiments I was working on needed shielding from other 2.4 and 5 ghz devices. Besides, I usually "setup" once I get settled inside the cage. I didn't even unload my cart yet, and my phone started ringing...

Re:Does not resonate with me

[Anonymous Coward]

Learn to read, dumbass.

Re:Does not resonate with me

[Anonymous Coward]

Dunno where they got the crap about "resonates".

Well, here's my thinking on this. IF it works. BIG if.

Take RADAR as an example. The basic idea is that the radio wave hits a surface, and causes the structure to vibrate (resonate) which results in a return signal. It does not really "bounce" off it like they usually say in laymen's terms... which is why stealth works so well.. it's not just the angle of the surface but also the crystalline structure of the material which when it resonates causes the return to scatter.

So IF (again, BIG if) this stuff really works, it's not really acting as a Faraday cage to block the wi-fi... it would just be causing a massive amount of scatter which would totally pollute the local signal, effectively making it unusable.

Myself, I am highly skeptical of the whole thing, and will believe it when I see it tested in independent trials.

Re:Does not resonate with me

[TrueKonrads]

Seriously... I work with a WiFi lab at work... I have a Faraday Cage in our lab... One of the techs forgot to install an optical isolator on the network cables, so for a few days the ethernet cables went right into the cage... Well, first day I went to use it, I locked myself in the cage, and was surprised that my cellphone started ringing... Without the optical isolators on the network cable, the RF signals were able to find there way into the faraday cage through the ethernet cables....
with that being said, I highly doubt that simply painting your walls will keep RF signals at bay... Even when the grounding wire was simply loose on the door to the faraday cage, RF signals would leak in...</quote>

This is very interesting! Do You have some physics explanation behind it? Could there be some externalities, such as, door not fully closed, ventilation open, etc ?

Re:Does not resonate with me

[TerranFury]

It's called an opto-isolator, and from the outside it has only electrical -- not optical -- inputs and outputs. Also most generally it's a generic circuit component, not special network gear.

Re:Does not resonate with me

[Ancient_Hacker]

Ah, no. "Resonance" is a very specific term, and has nothing to do with what happens with radar waves or with paint. Resonance can happen on the molecular level, but it's unlikely to match the Wi-Fi frequency band, plus the cross-section for capture of a thin coat of paint is miniscule.

Resonance can also happen on the macro-level, if you have structures that are conductive, 1/4 or 1/2 wavelength in size and with a matched impedance termination, none of which match what any paint would do.

Re:Does not resonate with me

[afxgrin]

Well he said "optical isolator" which is a totally different device.

http://en.wikipedia.org/wiki/Optical_isolator

Re:Does not resonate with me

[TerranFury]

Touché.

Why not share wi-fi?

[presidenteloco]

We do know the world would be a better place if everyone shared their wi-fi securely using
a technology like FON, don't we. (No I'm not associated with the company. Just recognize a
great concept when I see one.)

I'm seriously tired of how, particularly in the US, sharing wi-fi gets implanted in peoples'
brains as a criminal, borderline terrorist activity, with terms such as
"theft of tele-communication resources" and similar Orwellian mindf**k terms.

Re:Why not share wi-fi?

[RabidMoose]

Admit it. You're just bitter that your neighbor finally turned on WPA2, and now you have to go to the library to read Slashdot.

Re:Why not share wi-fi?

[Kylock]

There are plenty of security concerns with an unencrypted network.>While FON looks like it may be interesting to some people, I need all my bandwidth for my porn.

On a more serious note, many providers in the US will cancel or severely cripple your service if you use so much bandwidth in a month or other predefined timespan. There are other factors to consider.

Re:Why not share wi-fi?

[icebraining]

FON creates two different networks, one for sharing and one for private use, and AFAIK you can limit the bandwidth and throughput used by the public one.

Re:Why not share wi-fi?

[Anonymous Coward]

Of course there's nothing wrong with sharing a wireless network, when everyone agrees to it. I can't imagine anyone having a problem with that. But I don't think this story is really about the home user. I'd assume this technique would be more popular with a business storing highly sensitive data. Of course, there's an even better solution (ethernet), but that would mean the executives would have to give up their precious wireless.

Re:Why not share wi-fi?

[cheros]

Correct. And you can decide if you want to share free of get a kickback. If you share for free you are also entitled to access all other FON nodes in the world, if you share for a revenue share you have to pay. Pretty fair model IMHO.

However, I'm unhappy with a node on my personal network where someone can change code on the fly, which is why I took it offline a while back.

Re:Why not share wi-fi?

[Anonymous Coward]

Sharing with your neighbors is one thing, but actually profiting from it just rubs me the wrong way.

Re:Why not share wi-fi?

[RealGrouchy]

I granted my upstairs neighbour access to my wifi network for a while. Until I started getting the same problems as sharing the same hot water tank as my neighbour's unit.

The joy and fuzziness of sharing doesn't make up for low flow.

- RG>

Re:Why not share wi-fi?

[kalirion]

Mind opening up your bathroom to public use as well? Sharing means caring, after all!

Re:Why not share wi-fi?

[religious freak]

Hey, send me the MAC address for your router. I've got some pirated music I want to download, and I want to stop receiving these pesky RIAA letters. :)

Re:Why not share wi-fi?

[argStyopa]

Obviously he can't respond until he renews his library card.

Re:Why not share wi-fi?

[Lumpy]

Cripes buy a old dish antenna and build a biquad.

Snag internet from the house 2 blocks away. it REALLY opens up your choices for free internet.

I showed this to my nephew, he built one and it's aimed out of his dorm room window and hitting the subway across the quad about 4000 feet away. (clear line of sight) They use that link for P2P, most of the people on his floor think he is some kind of technology genius.

Re:Why not share wi-fi?

[monoqlith]

Are you surprised?

This is the country where sharing anything has been dismissed as 'communism', and straight-up avarice has been turned into the highest good.

Is it safe ?

[CharlyFoxtrot]

We all know about the hazards of lead based paints, so is this safe ? I'm assuming the plastic lining in aluminum cans is there for a reason. Perhaps adding panelling containing a solid aluminum oxide mesh of some sort would be better.

Re:Is it safe ?

[Fujisawa Sensei]

We all know about the hazards of lead based paints, so is this safe ? I'm assuming the plastic lining in aluminum cans is there for a reason. Perhaps adding panelling containing a solid aluminum oxide mesh of some sort would be better.

An easy solution would be to stop eating paint.

Re:Is it safe ?

[CharlyFoxtrot]

An easy solution would be to stop eating paint.

Yeah, but apart from kids eating paint chips when the house is demolished after a couple of decades the paint might get powdered into dust and be breathed in by the construction workers or just when someone sands it down or something. (I know: don't inhale, right ?)

Re:Is it safe ?

[blueg3]

Easy until you need to sand the painted object to apply a new layer of paint.

Re:Is it safe ?

[Caue]

check the ingredients on your deodorant. they all have aluminum oxide, and yes, you should use it everyday for your peers sake

Re:Is it safe ?

[Carnildo]

The plastic lining in aluminum cans is because the acid in most drinks will slowly dissolve the aluminum, giving the drink a metallic flavor.

Re:Is it safe ?

[jeff4747]

Lead is not Aluminum.

You are saying something like: "Sodium burns in air, so table salt must be an extreme fire hazard".

Re:Is it safe ?

[CharlyFoxtrot]

Well silver is safe to eat off, but so-called "medicinal silver" (colloidal silver) when ingested can make you turn blue. It's not unreasonable to look at the application of a supposedly safe material is it ?

Re:Is it safe ?

[CharlyFoxtrot]

I checked my deo, but no aluminum so I googled around and apparently it's an ingredient in antiperspirant which is in some deodorants (mine's the plain kind). Interestingly this turned up some debate on the safety of aluminum use :

"A small study in 17 women with breast cancer was quite widely reported in the news in 2007. It found higher levels of aluminium in the part of the breast nearest the skin, and the authors speculated that aluminium in deodorants might cause breast cancer. But the design of this study was not strong enough to draw that conclusion." From cancerresearchuk

And from wikipedia : "Aluminium, present most often in antiperspirants, but not usually present in non-antiperspirant deodorants, has been established as a neurotoxin in very high doses."

From what I can tell smearing it on your skin is probably OK and ingesting it in more than trace amounts should probably be discouraged :-) Thanks for the tip.

Re:Is it safe ?

[jeff4747]

Looking at safety is fine.

Looking at safety because something completely unrelated is dangerous is just fear mongering.

Re:Is it safe ?

[Lumpy]

You are comparing two unrelated things. Silver cup is nice to drink from, Colloidal Silver is used by raging idiots to poison themselves.

The dosage rates of the two are the same as your sunlight UV exposure compared to being in a cave in Colorado and standing on the surface of the sun.

It is unreasonable to make comparisons that are insanely different but worded to cause confusion and panic.

FYI:

Many of the idiots that dose themselves with silver will use a 3.5-20ppm (Part Per Million) solution. you get less than 0.1ppb (Part per Billion) from drinking from a silver cup. The amount of silver required to produce argyria is unknown. The FDA has concluded that the risk of using silver products exceeds any unsubstantiated benefit, and they are unsubstantiated. No proof in any way has been discovered in any real published lab tests. All lab tests show ZERO effects until you start hitting toxic levels and then the effects are detrimental.

What is so hard about using WPA2?

[Anonymous Coward]

You select WPA2-PSK in your router's config, press "generate key", make a note of the generated key, connect your laptop to the encrypted WLAN, enter the key, done. No beacon disabling, radio frequency shielding, MAC filtering, DHCP disabling or other nonsense necessary. It's like people are trying to test every option but the right one.

Re:What is so hard about using WPA2?

[ElectricTurtle]

Encryption can be broken with less effort than a physical wall. It's also fundamentally naive to propose that one layer of security of any kind is the silver bullet that makes all other layers unnecessary. I use encryption and MAC address lists together because it means that if somebody wants to get in they have to do two things instead of just one. Can people still get in? Duh. Everybody should already know that wireless network security is about making a harder target than the one down the street.

Re:What is so hard about using WPA2?

[Hal_Porter]

What about HARM missiles aimed at enemy WiFi transmitters? How do you feel about those as a means to prevent unauthorized access to your network?

Re:What is so hard about using WPA2?

[gad_zuki!]

The guy who can break your encryption can easily get past your mac filter pretty easily. The mac filter is there for people who cant or wont use encryption. So its kinda like locking your car but putting a note on the steering wheel asking "Please dont steal this car." The person who gets that far wont care.

Re:What is so hard about using WPA2?

[Anonymous Coward]

What is so hard about using WPA2
It is hard to use if you don't have a wireless router and/or network adapters that support WPA2. I have a Belkin F5D7230-4 v1444 router and a Belkin F5D7330 wireless bridge, neither of which support WPA2.

Re:What is so hard about using WPA2?

[Rick17JJ]

First, the author seems to be suggesting that painting your home or business with special paint would be easier than enabling WPA2-PSK encryption on your existing hardware. Then he goes on to say that "presently, most companies have to invest in complicated encryption software to deter hackers." Why would they need to invest in complicated encryption software, when then most devices already have WPA or WPA2 capability already built in?

It seems to me that they would just need to take the time to figure out how to properly enable WPA or WPA2 on their existing hardware.

Any older devices which only support WEP should be replaced with something that WPA2. The longer and more random the password is, the better. Ideally the password should also include at least a few numbers and punctuation characters too. Of course they should also change the well know default password on their wireless router.

The article does not mention what they plan to do to keep the radio waves from passing through windows. Were they planning to install special screens or shutters over the windows or what?

Re:What is so hard about using WPA2?

[Rick17JJ]

My understanding is that, if a sufficiently long and random key is used with WPA2-PSK, there is currently no publicly known practical way to break the encryption. But, I am not an expert. One article claimed that the encryption is still secure if the key is sufficiently long and random, and also includes at least a few numbers and punctuation symbols.

On the other hand I am not disagreeing that in general, layers of security are good.

One practical use for the special paint, which the article does not mention, might be for the problem of eavesdroping on the radio signals coming from most monitors and keyboards. I vaguely recall a Slashdot discussion which said that most ordinary keyboards have that problem, not just wireless keyboards. I wonder if the special paint would block the frequencies which those devices are unintentionally emitting signals on.

Unless more resistant keyboards and monitors are made available to the average consumer, a special paint might be the only easily available solution for that problem.

Re:What is so hard about using WPA2?

[Chris Burke]

Encryption can be broken with less effort than a physical wall. It's also fundamentally naive to propose that one layer of security of any kind is the silver bullet that makes all other layers unnecessary. I use encryption and MAC address lists together because it means that if somebody wants to get in they have to do two things instead of just one.

So you must think this aluminum oxide paint also counts as a physical security mechanism, since then to break down your wall someone would have to go through two layers: The wall, and the tiny layer of paint on it.

Now I haven't checked the prices, but I'm still 100% certain I could rent a bulldozer to go through the wall of your house for a hell of a lot less than it would cost to acquire the computing power to brute-force your password in a reasonable amount of time. I also consider "rent bulldozer, drive through wall" to be a lot less effort than researching, discovering, and then exploiting hypothetical weaknesses in WPA2.

Everybody should already know that wireless network security is about making a harder target than the one down the street.

If your neighbor down the street is using WPA2, and you're using WPA2+MAC filter, and you think that makes you a "harder target", you're kidding yourself.

Seriously. I used a MAC filter when I couldn't get WPA2 working on my linux box and my Wii, and prayed that was good enough (that's two levels of security!). Once I got it working, the MAC filter got turned off because it's nothing but an unnecessary annoyance and there's no way I'm subjecting myself to security theater.

Re:What is so hard about using WPA2?

[Kral_Blbec]

My router already has the capability to email me log files on a set schedule, would it really be that much more difficult to have it send an email/sms/prerecorded call to a designated recipient every time a new device connects? Sure a blackhat could probably fool it into thinking it was just an old connection resuming, but not if they didn't know it was going to do it. Further, how many real blackhats really go around and try to crack random residential networks?

Re:What is so hard about using WPA2?

[ElectricTurtle]

Cost is not the point. It might be cheaper to bulldoze the building, but it also vastly increases the likelihood of your being caught and prosecuted.

'Harder' is relative. Significantly harder? No. Somewhat or a little harder? Yes. It is still a layer. I also don't see how it's annoying as I very infrequently add devices to my network. I suppose if you put together whitebox notebooks for a living and had to test new wireless clients all the time it would be impractical, but if you only have to make changes a couple times a year for some people visiting, that's really too much?

Re:What is so hard about using WPA2?

[Chris Burke]

Cost is not the point. It might be cheaper to bulldoze the building, but it also vastly increases the likelihood of your being caught and prosecuted.

I thought the point was effort. For any meaningful definition of the term, going through your wall (or more likely, your door or window) is far, far, FAR easier than cracking your encryption.

And acting like you've increased the effort to go through your wall because you've added a layer of paint is exactly like thinking MAC filters are an "extra layer" of security.

'Harder' is relative. Significantly harder? No. Somewhat or a little harder? Yes. It is still a layer.

Insignificantly harder? Yes. It's a "layer" as much as the paint on your wall is a "layer" of protection from bulldozers. "Relative" to anything that matters, it's not harder at all. Adding MAC filters on top of WPA2 encryption is like putting tissue paper over a tank's armor -- anyone capable of penetrating the primary layer (which is nobody as far as we know, but hypothetically) would laugh at your "extra layer". Literally laugh at you for thinking that had made you even the tiniest scrap safer.

I also don't see how it's annoying as I very infrequently add devices to my network. I suppose if you put together whitebox notebooks for a living and had to test new wireless clients all the time it would be impractical, but if you only have to make changes a couple times a year for some people visiting, that's really too much?

Any meaningless inconvenience for the sake of security theater is too much. I should be able to add a device to the network simply by entering the password into that device. Adding the extra step of having to go to a machine already authorized, connect to the router, and add the new MAC address because it makes you feel safer is completely pointless. Ergo annoying, impractical, and too much.

Maybe that false sense of security makes you feel better, and thus it's worth it for you. Maybe not being able to bring water with you to the airport makes you feel safer. You're not actually any safer, but if you feel better, that's nice. I'm not going to engage in that meaningless crap unless I have to. I control my own router, ergo I don't have to engage in meaningless crap. It's that simple.

Re:What is so hard about using WPA2?

[Anonymous Coward]

I use encryption and MAC address lists together because it means that if somebody wants to get in they have to do two things instead of just one.

I wrap my money in a plastic bag before putting it in a safe because it means that if somebody wants to get in they have to do two things instead of just one.

Re:What is so hard about using WPA2?

[barry99705]

You are correct. Good password is the key, something like, LoV\8Y2C#!d1hDo4FYGuqM\Yfy?ARoFG6rgE#gIKHd[%.6x$!ABz[oio:1k}*y This password is functionally uncrackable with current technology. It is however a bitch to type into your portable gaming device.

Re:What is so hard about using WPA2?

[Lord Kano]

It is hard to use if you don't have a wireless router and/or network adapters that support WPA2. I have a Belkin F5D7230-4 v1444 router and a Belkin F5D7330 wireless bridge, neither of which support WPA2.

Yeah, it's so much more cost effective to paint your entire house in Aluminum Oxide paint than to buy a new fucking router...

Re:What is so hard about using WPA2?

[Lumpy]

an easier solution is to have installed a proper Wifi Setup.

Patch antennas installed on the perimeter and proper security can reduce Wifi Spillover out of the building by huge amounts if installed by people that actually know what they are doing.

Most Wifi Installations are installed by people that dont know jack about Wifi.

Re:What is so hard about using WPA2?

[Hognoxious]

It doesn't work properly on Windows XP in my experience. At least not all the time.

Re:What is so hard about using WPA2?

[Hognoxious]

Shut up, Berk. We see your point - that a million plus one isn't much more than a million. But it is more.

Re:What is so hard about using WPA2?

[Chris Burke]

Shut up, Berk. We see your point - that a million plus one isn't much more than a million. But it is more.

I won't shut up until you get my actual point, which is that in terms of actual security, enabling MAC filtering is completely useless if you have proper encryption. It isn't one added to a million, it is zero added to a million.

I guess maybe my examples weren't that great, because "tissue paper on top of tank armor" would imply slightly greater protection against anti-tank missiles and thus a very thick-headed person might conclude that covering tanks in tissue isn't completely pointless.

How about instead we compare it to another "second layer" of security I mentioned: Prayer. Is praying your wi-fi won't be hacked even the tiniest amount "more" protection? Because that's basically what you're doing -- praying that the person who can crack your WPA2 encryption can't or won't sniff your authentication packets out of the air. Even though just about every conceivable hypothetical method of breaking WPA2 would require that they do so. Which would essentially mean that if they break your encryption, they've already broken your useless MAC filter. It's completely useless!

If you actually understand this, there is no way you would advocate using a MAC filter on top of WPA2 as "another layer of protection". And that is my point. So you shut up until you get it.

It's not WiFi its see through walls mm waves

[mbone]

It's not WiFi they are protecting against - its "see through walls" mm waves that this will be especially effective against.

From the article :

"I'm working on a material that can absorb a larger range of frequencies. We are capable of making a paint that can absorb over 200 gigahertz."

This will stop Through-the-Wall Surveillance Technology cold.

Since 100 GHz is a 3 mm wave, and 200 GHz a 1.5 mm wave, they much have fairly small (100 micron) aluminum oxide particles in the paint.

Now, the paint will also stop any lower frequencies (longer wavelengths). However, these waves will go through any open holes in the paint that are much larger than a quarter of a wavelength or so - such as doors and windows. (Cell phones typically have wavelengths of about a meter to 10 cm - these low frequencies will also refract around household objects, while mm waves are much more line of sight.) So, I predict that in many cases the cell phone will work, while the "see through wall" technology will not. Of course, you'll have to make sure not to put what you are trying to hide in front of a window - or to get a very fine-meshed window screen.

Re:It's not WiFi its see through walls mm waves

[RoboRay]

"Of course, you'll have to make sure not to put what you are trying to hide in front of a window"

I don't need "see through walls" technology to see things that have been placed in front of a window.

Re:It's not WiFi its see through walls mm waves

[mbone]

Well, yes, that was an attempt at humor. A poor one, but it was all I had at the moment.

Although, I have been in several offices that had windows that were put behind barriers of some sort, so you couldn't see through them. It would be easy to forget that you had to paint those too.

Could this also enhance the signal?

[elashish14]

You should theoretically have enhanced signal quality if you're keeping it within the walls. All that radiated power that would have gone outside will remain inside, so there must be some sort of net increase in power radiated to your computer antenna.

Floors?

[Tubal-Cain]

...most pre-finished wood flooring uses aluminum oxide as a protective coating.

So... I can stop worrying about the gophers leeching my WiFi?

Re:Floors?

[Hal_Porter]

I think gophers would probably run cables underground.

Ahah!

[rickb928]

"You or your neighbors may be unwittingly using this already, as most pre-finished wood flooring uses aluminum oxide as a protective coating."

Finally, I can get rid of that kid in the basement!

BAHAHAHAHAHA! PWNAGE!

Usefull in heavily saturationed WIFI areas

[ACMENEWSLLC]

Where I am there is some WIFI (hidden or not) on every channel. There are large broadcast towers about half a mile from me which have various Internet over 802.11B from service providers.

My WIFI in my home has a hard time with all this. This paint would be a good way for me to improve my in home signal. A lot of my equipment doesn't support the new 5Ghz of 802.11N, so while I have 802.11N APs they do not help much.

Re:Usefull in heavily saturationed WIFI areas

[bugs2squash]

It sure will, perhaps you should get a roller on a long stick and paint over their antenna arrays

Re:Usefull in heavily saturationed WIFI areas

[Lumpy]

Most BG equipment also supports A which IS in the 5ghz range and was there long before any of this useless N stuff.

Even my wifes 4 years old Dell has an ABG card in it. and it works great on the A band that is wide open clear....

I have yet to find someone that comes over that cant attach to the A band. I guess if you have a really REALLY old laptop it wont have A capability, but you can buy a new mini-pci card for it on ebay for nearly nothing.

Re:Usefull in heavily saturationed WIFI areas

[dbcad7]

Not saying you.. but a common mistake people make with wireless routers is to treat them like modems and tuck them away out of sight.. In the 2Wire modems case, it needs to be standing upright..Those that set it on it's side are broadcasting signals into the surface it's laying on. It also helps some to elevate the router a bit if you can. Yes signals can go through walls and maybe it doesn't make sense, but give it a try and see if you get better results if you get a clearer path. The channel problem probably isn't as bad as you think, and I suspect it is more to do with your router, or the wireless adapter in your laptop.

limit my wifi? pah

[jackflap]

The number of times I've "borrowed" wi-fi from a neighbour, I felt obliged to leave mine open for everyone to use.

I did however install the Tomato firmware on my router, and use it's brilliant QoS to limit all machines but my own to 56k connections :)

Until someone opens a window or door

[loftwyr]

this sounds lovely. We just need to paint all surfaces and make sure all doors and windows are painted over and sealed. Nobody gets in or out and then we're all safe from RF leakage.

Of course, then everyone in the building dies and there's no more need for the security...

Re:Until someone opens a window or door

[Anonymous Coward]

Just have a two-door "airlock" system.

Idiot.

flamable much?

[Anonymous Coward]

I could just misunderstand all of this, but painting your walls with something so similar to thermite (http://en.wikipedia.org/wiki/Thermite) seems like a bad idea.
Anybody remember what caused the Hindenburg disaster? People should watch mythbusters more.

Re:flamable much?

[networkBoy]

this material is an Oxide. Thus it is already "burnt".

Re:flamable much?

[Anonymous Coward]

this material is an Oxide. Thus it is already "burnt".

I'm not the AC who posted the OP. Yet I feel I must point-out that in an aluminothermic reaction there are metal oxides in both the reagents and products. Of course, in the case of such reactions (like when thermite burns) you have molecular aluminum reacting with an oxide of a different metal producing an aluminum oxide. So you are right in this case, just not for the reason you think you are.

Re:flamable much?

[networkBoy]

nope, that's the very reason I thought I was right. I didn't elaborate about it though.

Specifically in any oxidizing reaction the active compound pulls oxygen from its environment to burn. In a silo explosion that is from atmosphere, in thermite it is from ironIII oxide.
-nB

Re:flamable much?

[Anonymous Coward]

Specifically in any oxidizing reaction the active compound pulls oxygen from its environment to burn. In a silo explosion that is from atmosphere, in thermite it is from ironIII oxide.
-nB

No, thermite is self-oxidizing. When it combusts it doesn't pull any oxygen from the enviornment. This means it can be ignited underwater or even in a vaccum, and trying to smother a reaction is a wasted effort. Instead, all the oxygen necessary for combustion is already in the metal oxide reactant, as shown by the chemical formula of a standard thermite reaction:

Fe2O3 + 2Al -> 2Fe + Al2O3 + heat

The only oxygen present is the O3 that starts in the Fe2O3 and by the end of the reaction is in the Al2O3.

A seperate, but more fundemental issue is that unlike your example of a silo explosion, uncontaminated thermite doesn't explode. It just burns really hot. Both are forms of combustion, but they are as distinct as hail is from snow (i.e. both are forms of frozen precipitation but with significant differences that have practical ramifications).

These two issues are why your conclusion was right, but your reasoning was wrong.

Re:flamable much?

[networkBoy]

you may have missed it but I mentioned that the active compound (alumina powder in this version of thermite) pulls oxygen from *it's* environment, not _the_ environment. In the case of thermite, alumina's environment is [mixed with] the ironIII oxide.

Re:flamable much?

[Anonymous Coward]

you may have missed it but I mentioned that the active compound (alumina powder in this version of thermite) pulls oxygen from *it's* environment, not _the_ environment. In the case of thermite, alumina's environment is [mixed with] the ironIII oxide.

Then you were not using conventional chemical nomenclature or concepts. In chemical formulas everthing other than the substances and energy involved in the reaction is intentionally ignored, thus the concept of an "environment" is unnecessary in that context. You have "reactants" or "reagents" at the start of a reaction and "products" at the end. The only other type of substance in a chemical formula would be a "catalyst", but catalysts still play a direct role in the chemical reaction.

Also, I've never heard or seen the word "environment" used in this fashion in conversational American English. To whit, "it's[sic, because "it's" is the contraction for "it is", not the possessive form of "it"; but that's besides the point] environment" indicates the surroundings of a person, place, or thing. You are using the phrase to describe some part of a mixture, a usage I've never encountered before.

Furthermore, unless I'm mistaken, we were discussing the entire chemical reaction, not a specific part of thermite. Your usage seems like passing an object from your right hand to your left, then claiming your left hand got the object from the "environment" because you only want to focus on your left hand while describing the process of passing of the object. In this case, I find the establishment of the arbitrary distinction very odd, to say the least.

Re:flamable much?

[Hognoxious]

Shut up, you pedantic faggot. He said several times that the oxygen came from the iron oxide. Just learn to fucking read you emo OCD twerp.

Great

[geekoid]

Now please paint movie theaters with it.

oh, and for the alarmist:
The movie theater can put a sign outside indicating that there signals will be blocked.

I know this isn't cell blocking, but a lot of text Traffic is moving to wi-fi.

Won't someone please ...

[PPH]

.... paint the BBC's broadcast antennas with this stuff?

The BBC reports...

My basement does a good job

[Jim Hall]

I happen to live in Minnesota, where most homes have basements. Our Comcast cable enters the house through the basement, so I figured it was a convenient place to hook up the WiFi access point. The WAP is sitting on the bottom shelf of a bookshelf I have there.

The net effect is that I have great WiFi signal throughout the house. I have a wood frame house, and WiFi signal is not retarded by normal wood construction. However, I get almost no signal as soon as I step out the back door onto the porch. A few feet away from the house, I can't pick up the signal at all. I've also tested it from the street, and it's like my WAP isn't even there. No, I'm not using any special paints or "Faraday cage" wallpaper.

That's because basements are constructed from cement blocks, which do a pretty good job of retarding WiFi signal. Not to mention my basement is 6-7 feet underground (there are windows at almost ceiling height) and all that dirt also helps block the signal. I figure I'm pretty safe from snooping. Sometimes it helps to just be incrementally harder to get to than the next guy. If you're a wardriver who's interested in free WiFi, my neighbor two doors down is an easier target (his WAP is on the second floor of his house, so he's essentially broadcasting to the whole neighborhood.) Or I suppose you could drive down a block and a half to the coffee shop who runs a completely open WAP.

* And yes, I do use good WAP security, with encryption, long passphrase, MAC filtering, only wired connections are allowed to connect to the admin screen.

Re:by misspelling aluminium?

[Anonymous Coward]

From the surprisingly well-written/sourced Wikipedia article:

Present-day spelling

Most countries spell aluminium with an i before -um. In the United States, the spelling aluminium is largely unknown, and the spelling aluminum predominates. The Canadian Oxford Dictionary prefers aluminum, whereas the Australian Macquarie Dictionary prefers aluminium.

The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990, but three years later recognized aluminum as an acceptable variant. Hence their periodic table includes both. IUPAC officially prefers the use of aluminium in its internal publications, although several IUPAC publications use the spelling aluminum.

Translation: Quit being a douchebag.

Flawless Solution or Not

[Anonymous Coward]

"You or your neighbors may be unwittingly using this already, as most pre-finished wood flooring uses aluminum oxide as a protective coating."

This is to stop the CHUD from getting free wifi.

Unless. . .

[JSBiff]

Unless this compound does something like absorbing the RF, and in the process, attain a slightly higher temperature/thermal energy state. If that's the case, it would be like shining your flashlight on a black surface (most 'black' paint still reflects some light, but I hope you get the idea).

No any practical use

[puhuri]

Even if the paint blocks radio waves, it would be usable only in windowless rooms without electricity. Radio waves have a property going where you do not want to, and not going where you want.

For example, I know multiple RF-shielded rooms that were very good when they were build in early 1970s. However, one has no problems using cell phone inside of those. To get sufficent protection to GHz rf signals, you must have proper filters in all wires going to room, including all copper network cables and power lines. Same for all ventilation and doors.

The paint is just the easy part that you can replace with copper plates. The rest is much harder.

i already have this on my house

[shadowrat]

the aluminum siding does a great job of keeping wifi in my house. i can hardly get a signal in my yard without LOS to the router through my window.

after installing a steel garage door, it did a pretty effective job of preventing my garage door opener from working either :(

Thermite?

[meerling]

So they are using paint that includes a highly volatile substance.
I wonder what else is in there to act as a stabilizer to negate the massive fire hazard.

Re:Thermite?

[blueg3]

Thermite is a mixture of aluminum and iron oxide, which is not the same as aluminum iron oxide.

Re:Thermite?

[jonbryce]

The "oxide" helps a lot there.

Re:Faraday Cage

[Anonymous Coward]

And earth (ground) it.

strange perception of frequency

[Anonymous Coward]

How are cellphone signals at 1.5GHz much lower than WLAN signals at 2.4GHz? What cellphone operates at 1.5GHz anyways?

It seems that he author and the expert being interviewed do not know what they are talking about.

Also the paint will act as an absorber and not a reflector. It will not be the same as a lining your walls with aluminum foil or a faraday cage. Also if you do line your walls with aluminum foil, you can actually amplify the electromagnetic fields by creating resonant room modes.

Hmm

[Anonymous Coward]

Encryption can be broken with less effort than a physical wall.

Both respond to a brute-force attack.

o rly?

[Anonymous Coward]

i'm using your precious network right now

Doesn't this also block over the air (OTA) for TV?

[antdude]

I noticed the one year old shutter window doors, in my room at home, lower digital TV feeds with OTA antennae (rabbit ears and DB2 bowties) if the shutter window doors are closed (even partially). Annoying. :(

That's nice.....

[fataugie]

Now I can slowly microwave myself.
Talk about stewing in your own juices.....mmmmm, fat Sys Admin flavored.

Wrap up the AP and your laptop with tin foil

[Ivan Stepaniuk]

You will save a lot of paint and hassle.

Weird coincidence...

[kaini]

Earlier today, I saw my neighbours buying a few tins of this stu#&[NO CARRIER]

Gives a new meaning to "rough coat"

[Neanderthal Ninny]

Aluminum Oxide is also in sand paper and other abrasive mediums like anti-skid surfaces. Which grit size did they they use for this; 50, 100, 500, 1000?

misunderstood crap

[pbjones]

currently blocks RF at 100GHz, which is just about nothing to do with Wi-Fi or Cell/mobile phones. I doubt if it'll affect anything that you currently have in a home or office, I suspect that clay bricks do a better job. Actually, I'm wondering if there is a translation problem here and that the figures are incorrect.

Al2O3

[cratermoon]

Shouldn't this story be tagged "ruby"?

oxides

[cratermoon]

I'm skeptical. Next they'll be telling us that titanium oxide can block sunlight!

OP a douche? hardly!

[Anonymous Coward]

OP is hardly a douche. He is merely pointing out that IUPAC had to go as far as changing its standard because Americans cannot understand nor speak the English language correctly. Hence why they invented this abomination called "US English".

Doesn't this sound like a

[Anonymous Coward]

great big giant TIN FOIL HAT !?!?!?
It DOES sound like a TIN FOIL HAT for my house!
Will it block the rays from the space aliens? When they realize they can no longer control me from either Xatox or from the mother ship, will they return and re-drill the holes in my teeth and re-apply the rectal probes?

More seriously, I did at one time work for a spook house, and saw how electronic signals ala TEMPEST (see wikipedia), were defeated (buildings sealed from electromagnetic radiation including double layers of door screen over the windows, grounded sheet steel in the outside walls and roof (basically a giant Faraday trap). Only one computer per floor connected to the internet, and controlled access with media going into the room subject to really powerful magnets. Data downloaded from the net could be added to the local lan, after a small team scans it for bugs, viruses and malware.

Window coating, which blocks signals

[Ux64]

Actually I live in Finland, and here metal coated thermo windows are common. Unfortunately if I put my cell phone 5 cm outside window, I got full 3G reception and 5 cm inside, it's totally gone. So yes, you can also have metal finish on windows, which blocks signal. It also cause problems to normal FM receiption as mentioned.

I didn't wish for this, because now my wireless (3g) data is over 10 times slower than it would be without that finishing. (3G HUSPA -> GSM 2.5G EDGE)

Re:Window coating, which blocks signals

[pestie]

I lived in an apartment complex in the US that had windows like this. I only discovered it when I decided to try getting a satellite TV signal through the window. The complex didn't allow satellite dishes, but I had a south-facing window. I figured, hey, why not just put the dish indoors? Glass doesn't block 10/11 GHz signals! It worked great when the window was open, but closing the window caused 100% of the signal to be blocked. I eventually ended up making an insulated double-paned "window" replacement out of two sheets of acrylic with spacers to create an air gap and sealed it along the edges with foam tape. That didn't attenuate the signal noticeably and I had my satellite TV.

two words

[Tastecicles]

space blankets.

you know, those aluminised biaxially-oriented polyethylene terephthalate sheets that athletes use to keep from cramping? I have a radio-free oasis in my home, one small room with the stuff stuck to the walls, under the carpet and on the ceiling. I live less than one hundred yards from a cell relay; in my living room I have 5 bars. I walk into my oasis, no service. there's no wireless either. No radio signals of any kind whatsoever. No FM, AM, DAB, TV... it's a radio desert in there.

Re:two words

[fireylord]

one question: why??!???

Re:OP a douche? hardly!

[Anonymous Coward]

From the same article:

The earliest citation given in the Oxford English Dictionary for any word used as a name for this element is alumium, which British chemist and inventor Humphry Davy employed in 1808 for the metal he was trying to isolate electrolytically from the mineral alumina. The citation is from his journal Philosophical Transactions: "Had I been so fortunate as..to have procured the metallic substances I was in search of, I should have proposed for them the names of silicium, alumium, zirconium, and glucium."

By 1812, Davy had settled on aluminum. He wrote in the journal Chemical Philosophy: "As yet Aluminum has not been obtained in a perfectly free state." But the same year, an anonymous contributor to the Quarterly Review, a British political-literary journal, objected to aluminum and proposed the name aluminium, "for so we shall take the liberty of writing the word, in preference to aluminum, which has a less classical sound."

Contrary to your obviously biased opinion, it was an anonymous, self-important Brit with a stick up his "arse" who suggested the name be changed from the proper aluminum to the unnecessarily superfluous aluminium, which he presumably found to be more melodious to his prissy English ears.

dual-mode wireless router?

[Anonymous Coward]

Most of my devices can use WPA, but one is out-of-date and only supports WEP- so we use WEP. Is there any solution other than getting a second router?

A small correction

[jandersen]

The BBC reports on people using aluminum oxide in their paint to block Wi-Fi signals...

This is not likely, considering that BBC is British; "aluminum" is an element that only exists in America, where everything is different - in UK we use something called "aluminium"; please note the "i", the difference is crucial. Oh, and don't forget the smilie: :-) - this was a classical piece of humour (again, note the "u" ...)

Re:OP a douche? hardly!

[Hognoxious]

Get back to us when you put sodum chloride on your freedom fries and have a barum meal before an x-ray, you fat cunt.

Does this mean I can paint my helmet

[Anonymous Coward]

I want to get all the aluminium foil out. The crinkling sound makes it hard to hear gun shots.

It sounds good, but it's not true

[WindShadow]

The FCC allows transmitters below a certain power level, and transmissions on certain very high frequencies without license. There is a PDF doc on that, and a discussion on the ARLL site which shed light on this.

Not all transmitters need be licensed, not even all operated, although if they are commercial products they must be registered. That's why some devices have the legend This product does not emit any RF at power levels or frequencies regulated by the FCC instead of an FCC number.

There's a ton of detail at those two links which clarify that there are some unregulated areas, although they are not where you would use them for blocking cell phones.