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Crystal Pattern Matching Recovers Obliterated Serial Numbers From Metal
chicksdaddy writes Criminals beware: researchers at the National Institute of Standards and Technology (NIST) have figured out how to recover serial numbers obliterated from metal surfaces such as firearms and automobiles — a common problem in forensic examinations. According to this report, NIST researchers used a technique called electron backscatter diffraction (EBSD) to read, in the crystal structure pattern, imprints on steel that had been removed by polishing. ... The more perfect the crystal structure, the stronger and clearer the pattern. Software can then calculate the pattern quality to reveal crystal damage; areas with more damage produce lower quality patterns. In the NIST experiments, described in Forensic Science International, researchers hammered the letter 'X' into a polished stainless steel plate. The letter stamps were as deep as 140 micrometers, meeting federal regulations for firearm serial numbers. The researchers then polished the metal again to remove all visible traces of the letters, and collected the EBSD diffraction patterns and pattern quality data and analyzed them for evidence of the imprints.
What if you use some tool and hammer to overstamp the serial numbers. Like scribbling over it. Then grind it down. Or if it is in a place that can be heated and cooled... like annealing... where any loss in strength from the operation, were it to happen, wouldn't be an issue. Would that change the underlying crystal structure significantly. I'm sure it would affect it some, but would it be enough to allow the crystal structure to 'reset' and erase the original stamp marks?
-- I ignore anonymous replies to my comments and postings.
All you need do is gain employment at any Bank and work your way up the slimy corporate ladder. Steal money legally by getting a job where the money is.
And this becomes largely irrelevant
The FBI has been recovering filed off serial numbers for at least a decade based on the changes in metal grain that result from stamping. Is this just a more sensitive method for doing that?
What the fuck are you waffling on about?
If you do it stupidly, like put a "1" through an "A", it would be fairly obvious and narrow the search down.
Punching 1 through an A leaves the firearm with two possible choices in that digit. Do this for 9 digits, and you get 2^9 = 512 possibilities. Punch twice through each digit and you get 3^9 possibilities.
In fact, punch *all* the digits in each position, then file it down.
This will rapidly be entered into the "big book of best practices" for criminals.
And it's also a moot point, since easy access to guns reduces crime, and it's likely that 3-d printed guns will be easily available in the next decade or so.
(And so what if the 3-d printed gun is reliable for only the first couple or shots? That only means that you use your 3-d printed gun that took 2 hours to print and $3 to build a couple of times and then melt it down.)
Defeated by a $59 Dremel tool that completely removes the metal from that area of the frame...
140 micrometers is 0.0055 inches
which is about 6 thousandths of an inch
which is about 3 head hairs stacked
which is why I need more crystal to stay ahead of this blue persuasion that has been following me
Yeah they figured it out years ago, like back in the 1990's.
All you need is a spot welder.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
It has been possible for decades to recover serial numbers by chemical etching, which is sensitive to changes in the crystal structure. All you need is a polishing implement and a bottle of etching gel. What is the added value of this EBSD technique? I can see a big disadvantage: you need equipment (a scanning electron microscope) worth a few hundred kEUR and the object with the erased serial number needs to fit into the vacuum chamber of said equipment.
The article mentions that etching techniques don't always work, but they don't state that their technique does work on samples for which the etching method doesn't work...
Avantslash: low-bandwidth mobile slashdot.
there is techniques to read pulished-out stamped numbers (eg. on car frames) since ages.
Clever scientific method meet 4.5inch angle grinder.
Wrong choice of word, surely?
"destroy utterly; wipe out."
If you did obliterate it then they've have zero chance of recovering the information.
Metal grain boundries change if you heat the metal up. This also removes the temper, but rapid heating followed by rapid cooling (Such as by very high speed friction sanding, then submersion in water or oil) will change the crystal grain structure of the metal pretty deeply if done right.
Failing that, sanding off the top layer, then applying heat with a heat gun for a few minutes, then clenching with a cold oil pour will have the same effect, but more reliably.
Seriously, this is how heat treatment of steels works. Steels and other metal alloys go through various phases of crystal growth types under different temperature and pressure environments. They grow when hot (but not molten) which is why the metal weakens. If you heat it up hot enough, this processes changes into annealing where the crystals break down from thermal forces and the metal becomes amorphous. Flash cooling results in a densely packed matrix of tiny metal grains, which strengthens the metal.
Seriously-- all you have to do is alter the crystal growth pattern under where the serial number was. Heat treatment will do exactly that.
Yessss, goooood. Let the hate flow through you...
All those moments will be lost in time, like tears in rain.
You need to melt the metal so that it flows and reforms. Blowtorch? Erase with a laser?
This could actually be useful for gun shops, since we have to meticulously catalog the serial numbers of all firearms that come in and go out. We often get older (like, 150 year older), used firearms where the serials are worn down and difficult to read, even with a jewelers loupe.
Or rather it would be useful for gun shops, if the process isn't as cost-prohibitive as I presume it will be.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
It's a well-established fact at this point.
The study cited includes data from the UK, which is seeing a massive increase in crime over the last two decades. From that study:
bytheyear2000violentcrimehadsoincreasedthatEnglandandWaleshadEurope’shighestviolent
crimerate,farsurpassingeventheUnitedStates.
This should, at the very least, satisfy everyone's demand for a study, which includes England and the UK.
Also, US states with relatively easy access to guns *do* see a lower crime rate. Compare New Hampshire and Texas with, for example, Illinois and Louisiana.
Heard about this decades ago.
... how to recover serial numbers obliterated from metal surfaces such as firearms and automobiles ... In the NIST experiments... researchers hammered the letter 'X' into a polished stainless steel plate.
Just had a look at the few automobiles and firearms I own. None are made out of polished stainless steel plate.
Also, while my oldtimers are stamped, I recall seeing a few items of more recent manufacture that had the s/n milled into the substrate.
Free, as in your money being freed from the confines of your account.
In this case, use micro-beads for the peening. There are commercial alumina (a hard ceramic) microbeads available. The object is to get enough subsurface damage ro mask any imprint damage.
Well, time to defund the NIST. This is an attack against the rights of gun owners everywhere. This slippery slope will inevitably lead to mass gun confiscation and imprisonment for anyone daring to express their second amendment rights.
Banksters can loot trillions at will sans steenking serial numbers. Let's see some Magical Chrystal Pattern Matching to put a stop to that.
Then it's gone - but with steels the time and temperatures required not only make it impractical but would also make the thing the numbers are stamped on useless. Even though iron (thus steel) is not a good conductor it's still enough of a conductor that if you anneal one part of it the rest of the engine block (for example) is going to be heated up enough for long enough that it will ruin the structure that makes the steel useful. Annealing steel is a lot more time consuming than many other metals. However, if it's an aluminium alloy it's probably even worse because it conducts much better and is even more dependant on cooling/heat treating to get a useful structure - you can anneal it but end up with a large area not strong enough or tough enough to do the job.
Grinding it out deeper than the damage done by the stamp is a different story.
A very very old smithing trick, maybe Hittites old, is to stamp the metal grind it flat, polish and then apply a weak acid, even vinegar, which will preferentially attack the metal that was damaged by the stamp and make whatever pattern was applied visible on the polished surface. With iron and steel it's a darker grey on a light grey surface.
It works exactly the same way with plain carbon steel with a rough surface or even mill scale still on it. They just used polished plate to reduce the variables. Stainless is also a bit of a bastard to etch so the usual method of just acid etching to recover serial numbers is less likely to work on stainless than with your carbon steel automobile and firearm parts.
That will still distort the metal underneath though probably not a deep as stamping.
Who erases serial numbers, and doesn't anneal the base material? Idiots.
I art more snarky, and terse than thou. I art Slashdot!
Why is it that cops ever recover murder weapons at all? Seems to me that if you have a gun that could incriminate you, the obvious thing to do is get a bench grinder and turn it into a pile of filings.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."