Thread: Dry ice ground fog

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I have a scene that requires major ground fog pouring out of a vehicle (cargo van).. I've used dry ice before for short term applications and it's awesome in a pot of hot water. The problem is that it rapidly cools the water and the effect is over.

I'm planning on using an electric hot plate to keep the water as warm as possible and I was just curious if anyone else has tried this?

Thanks!

No one uses dry ice anymore? Am I that old fashioned?

Most people have found that dry ice isn't worth the trouble & cost.
They have moved on to use fog chillers (connected to a fogger) instead, which are less expensive for longer effects.

If you really want to use dry ice, put the dry ice in a pot of hot water, on a burner to keep the water warm. Another trick is to put the ice in saltwater to keep the water from freezing.

Even with a hot plate, expect a LOT of ice to form. Also expect to burn out your hot plate in fairly short order because of constant over-use. They really weren't designed to be left on for hours at a time.

I have had success with my system for several years.

I used an old boat gas tank. It's made of steel. Holds about a gallon and a half of water.

It also fits neatly on top of one of those coleman camping stoves with 2 burners.

I also bought Dry Ice pellots for about $25.00 per 50 lbs.

Here's how it works:

Cut a large round hole in the top center of the gas tank. Attach a large coffee can to it and seal all the cracks with something heat resistant. The coffee can is just the right size to attach a dryer hose to. Cut a smaller hole in the top of the gas can and attach a computer cooling fan directly over the hold so that it blows into the tank.

Set the tank on top of the coleman stove and fill it with about a gallon of water.

Here's the problem....You need to have someone there constantly feeding the tank with pellots or devise some way to autofeed it.

Just drop a small handfull of pellots into the original opening in the tank every minute or so and put the cap back on.

Keep the water temp at about 80 or 90 degrees F.

Turn on the fan and it will push the fog right out of the coffee can and dryer hose.

I find that this method works better than the big commercial tanks they rent with the 50 gallon drums and submersable heaters.

You don't have to worry about blowing a circuit because of the current the heaters draw. You don't need any power at all.

The heaters could never keep up and keep the water hot if you used the dry ice continuously, so after the first few minutes, the effect tapers off to almost nothing and it takes half an hour to recover.

Because I am using such a small volume of water and an adjustable flame under it, I can keep the water at the desired temp and use it all night.

You might want to have extra water handy to refill, but you are keeping it below boiling, so it should last all night.

If you heat the water too hot, you will just get steam. Not the desired effect. If this happens, just dump in a ton of pellots, and that will cool down the water to a better temp and you should be back in business in a matter of seconds.

Just keep an eye on the temp. Use a cooking thermometer or something.

I don't know if this is going to sound crazy but I was having a problem keeping my fog on the ground so a friend told me to do the following take a foam ice chest cut a hole in it and run a dryer hose to the end where the fog comes out and into the ice chest cut another hole on the other side of the ice chest so that the fog can come out after a little bit the ice chest will cause the fog to cool and stay low instead of rising quickly try it out it worked for me.

I love dry ice for some applications and have used it in Halloween's past. The only complaint in using dry ice is that it gives off carbon dioxide gas so if there will be little ones or pets walking through or near it, it can literally take their breath away, with possibly disastrous results. If you want the sort of "crawling fog" like you describe, try using a fogger or more than one, even combined with a home made fog chiller and you'll be happy with the results, you'll get that creeping fog for sure and in pretty good amounts. Also, from what I've read, there are no ill effects from breathing fogger fog, after all it's only Glycerin and distilled water. Check the internet for home made fog juice, i make my own every year.

OpenTrackRacer,

One popular way to keep the water from freezing is to use a fish tank warmer. You can pick one up from any pet store.

Hope this helps answer your question.


-Tucker
http://dryicenetwork.com

Using Dry Ice fog continuously really depends on how much fog you want.

I have a large 55 gallon tank with 2000 watt water heater in it. It gets used in theater to make scenes like this. This is the wolf chase scene from B & B.

The setup I have filled a 40ft wide 10 ft deep section of stage, plus 25 ft of wing and loading dock with 2 ft of dense fog in about a minute. But that's with dropping about 50 lbs of ice pellets in the tank, so the effect would only last a few minutes before the tank was nice and cold, and it starts at 150* F.

Now with 35 gallons of water at 150* and a heater that size it could easily keep up with running 5-10 lbs continuously. The thermostat in it can handle up to 2 4k heaters, so I'll be adding another 2k soon.

You WILL burn off water while creating the fog as the fog is actually water vapor and CO2. Doing the show this summer we'd burn about 170 lbs of ice a show and 2.5 gallons of water.