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Old November 6th, 2002, 12:28 AM   #16
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I thought dry ice was frozen CO2 (what you exhale) and therefore, when it "melted" it would simply release gas into the air, not liquid.
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Old November 6th, 2002, 01:20 AM   #17
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Re: Dylan

<<<-- Originally posted by Marc Betz : For Chirst Sakes Don't you know anything???

You buy it at DRY ICE "R" US

Dopey.

Actually look under cryogenics in the yellow pages.

Marc

: ) -->>>


:)
Thanks. How much is a going price for it, and what amount would fill what kind of volume? Ballpark idea anyway.
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Old November 6th, 2002, 01:48 AM   #18
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I'll think you'll be disappointed how miniDV renders fog that is fairly even. It looks great on film, but DV has a fraction of the resolving capability of film. I shot some footage up high on a mountain in the cloud layer the amount of noise and banding was terrible. Since then, I've watched for such things in film and even on film, there is a noticeable jump in noise.

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Old November 6th, 2002, 02:43 AM   #19
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Whatever you do, don't touch it without wearing gloves---it's damn cold! (Frozen carbon dioxide. Ouch.)
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Old November 6th, 2002, 06:20 PM   #20
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Hey Josh

I think its about 10 bucks a pound. It's terrible for making realistic fog or smoke but it is totally inert so you can use it (if you chip it up into small pieces) in drinks or to roll a fog out of a closet or small room during a halloween party etc. It doesn't really fill up an area it just kinda meanders around the floor a bit, but it rolls like fog. The more humid it is, the better it shows up.

It will evaporate (melt) in your freezer so it doesn't have a long shelf life.

Just think, a tray of smokeing shots being handed out to your guests at a party.

Hmmmmmmm

I need a drink
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Old November 7th, 2002, 07:08 PM   #21
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I don't know if this stuff is still around. Back in the '80's on movie sets the SFX guy's used "bee guns". It was a container used by bee keepers to smoke bees. It had a small bellows-type handle that you would pump. It worked great!
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Old November 7th, 2002, 07:40 PM   #22
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Re: Hey Josh

<<<-- Originally posted by Marc Betz : It [dry ice, aka frozen CO2] will evaporate (melt) in your freezer so it doesn't have a long shelf life. -->>>

To be perfectly accurate about it, your freezer dry ice neither evaporates (changes phase from liquid to gas) nor melts (changes phase from solid to liquid). It sublimates, that is, it changes phase directly from a solid to a gas.

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Old November 7th, 2002, 09:37 PM   #23
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If you buy dry ice, put it in a thermo "picnic basket type container." It should last for a few days at least.
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Old November 8th, 2002, 02:33 PM   #24
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Some fog machines work by vaporizing mineral oil.

Here are instructions for making such a machine:

http://www.iosphere.net/~rheslip/html/body_fog_machine.html

Here is a report on the health effects:

http://www.mindfully.org/Health/Stage-Fog-Risk.htm

My advice is don't mess with the heated glycol.
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Old November 8th, 2002, 05:14 PM   #25
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Robert

I did not want to confuse anyone w/sublimation. It would not have worked in the original post, but the reply was the perfect place to point it out.

It sublimates best in a drink called a fog cutter : )
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Old November 12th, 2002, 05:50 AM   #26
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africats,

I've seen the bee guns used in some of those "Making of..." shows. I wonder what they put in them...bees and a tiny pack of cigarettes?

It would probably have to be smoke considering how simple they are.
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Old November 12th, 2002, 10:35 AM   #27
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Robert
"To be perfectly accurate about it, your freezer dry ice neither evaporates (changes phase from liquid to gas) nor melts (changes phase from solid to liquid). It sublimates, that is, it changes phase directly from a solid to a gas."

Very true, someone over at the VX2K thread basically told me I was full of it when I said the same thing a few months ago.
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Old November 12th, 2002, 10:48 AM   #28
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I've seen cylinders of Nitrogen in hospitals and on industrial sites. Why couldn't it be put into a smaller container with a nozzle, rather than a valve?

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Old November 12th, 2002, 11:31 AM   #29
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Disposable cans would never hold that much pressure. The industrial cylinders of dry nitrogen are at approx 2000 psi. My industry uses dry nitrogen as an inert purge to prevent oxidation and as an agent to pressurize and test for leaks. For safety purposes the cylinders are only used with the appropriate pressure regulators.

The disposable cylinders that we buy for cleaning and blowing are cans of liquified gas (refrigerants). much like a tank of propane or butane the liquid propellant boils off and exits the can as a gas. Tip the can and you get liquid. The liquified gases are non toxic and non flamable. If the cans were just filled with a compressed gas , we'd get about one or two shots per can.

Sorry for the tangent. I shouldn't get my shorts in a knot over something so trivial.
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Old November 12th, 2002, 03:44 PM   #30
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You can get small (45ci-110ci) compressed air/nitro tanks for paintball guns that hold up to 4500psi. They can be regulated down to next to nothing so you can release as much or little gas as you want. I didn't really think nitrogen would create a smokey effect, but I guess?? Anyway, they sell for $100-$400 on average, and are available at a paintball store near you.
If anyone tries this, let us know how it works out
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