Slashdot Mirror
Fun with Fog Generators
BoomZilla writes "Only
10 or so shopping days to Halloween. If you're at a loss for a project
this weekend check out gotfog.com for
a full set of detailed instructions on the construction of a Fog
chiller. "What's a fog chiller?" you may ask. And rightly so.
Let me explain. A fog machine dumps fog juice on a heating plate to
produce oodles of the white, floaty stuff. Problem is that it doesn't
hug the ground like you see in the movies. An alternative that is employed
to create the ground-hugging variety of fog is a dry ice machine (which
heats up dry ice and disperses the resultant cloud of fog). The problem is
that dry ice is (a) expensive and (b) not always that easy to get. Enter
the fog chiller. The chiller can be built very inexpensively (major cost
is the sacrifice of a largish cooler) and works with a regular fog machine
that consumes low-cost fog juice. Go on, give it a try. You know you want
to. And just imagine the look on the faces of your little ghouls and
ghosts come the 31st when your house looks like boot hill on steroids."
Use a container (I use a Tupperware box) that is twice as big as the volume of grass you wish to dry. Make a few small holes in the lid, to allow the gas to escape. Put equal volumes of bud and dry ice inside, loosely packed, with the dry ice underneath the bud. Put the lid on and make sure it is properly sealed so that the only way for gas to escape is through the holes in the lid. Put the box into a freezer, lid upwards. This is to keep the material as cold as possible, prolonging the sublimation process for as long as possible. The dry ice will begin to sublime pushing all air out of the box and surrounding your buds with bone dry co2. The totally dry atmosphere will begin drawing water molecules out of the plant material. Check the tub after 24 hours and then every 24 hours until the dry ice has all gone. When the ice is all gone -the buds should be completely dry and smokeable. If you find that they are not quite dry then put some more dry ice into the box, place the lot back in the freezer and wait until they are done.
OOh, finally, something on Slashdot that I can comment authoritatively on! (I'm a stagehand, and often use atmospheric effects)
I would just like to refute the posters assertations about dry ice foggers. Firstly, dry ice is certainly NOT expensive. Prices usually fall in the $0.50 to $1.00 / lb range, depending on the form (block, pellets, etc.) and supplier. Which brings me to the second point, availability - Go to your local grocery store. If they don't have it (most in southern and western states usually will), they'll be able to tell you who will.
Once you have the dry ice (I'd suggest about 25-35 lbs. for a good, long show), it's very easy to turn it into fog. Step 1 - pour hot water over it. Step 2 - there is no step 2! There are many many pre-made machines for this purpose, such as the City Theatrical Aquafogger, which are available for rental, but it's such a simple device, anyone here should easily be able to make one on their own.
The basic things you need are as follows - a barrel - big enough to hold the dry ice, plus all the hot water that will be poured through it. A basket, to hold the dry ice in, above the level of the water. A fan and a tube, to take the resultant fog, and put it where you want it (dryer hose works very well for this). And finally, a method for pouring large amounts of very hot water over the dry ice - the faster the rate of pour, the faster the sublimation of the dry ice, and hence, the larger the volume of fog generated. For the water-pouring, something as simple as a 5-gallon pail is quite sufficient.
One down side to a dry-ice fogger, however - that 25lb load will only last about 10 minutes, and the fog only a few minutes longer than that. If the effect that you're looking for is a long-lasting, room-filling, hanging haze, then you'll be better off with an oil-based fogger. (Just avoid prolonged breathing of concentrated amounts of the fog - it's been shown to produce many respiratory ailments - and that was the professional stuff)
If all the world's a stage, anyone who says they want better lighting spends far too much time in a dark theatre.
The problem with dry ice is that it's dangerous (CO2 asphyxiation) in closed areas, and outdoors nothing will work terribly well.
I've put up a mirror of the special projects page at gotfog.com, as well as the "making fog hug the ground" and "vortex" special projects. The mirror should be significantly faster than the original, and can be found at http://www.msu.edu/~brownd41/mirror/gotfog/index.h tml