Theatrical & Special Effects

When Dry Ice is combined with hot water it will produce vigorous bubbling water and voluminous flowing fog. A theatre fog machine is generally a 30 to 55-gallon metal or plastic water barrel with a 110-volt or a 220-volt hot water heater to keep the water hot. Dry Ice is placed in a bucket with holes to allow hot water to enter. When the bucket is lowered into the hot water fog is instantly produced. The resulting water vapour fog is gently blown by a fan and directed to the desired area by an air duct tube. Fog stops whenever the bucket of Dry Ice is pulled out of the water. More modern fog machines pump heated water over a tray holding the Dry Ice.


Dry Ice when combined with hot tap water can produce vigorous bubbling water and voluminous flowing fog. For example, with 5 pounds (2.3 kg) of Dry Ice in 4 to 5 gallons (15 to 19 liters) of hot water, the greatest amount of fog will be produced the first 5 to 10 minutes. There will be far less fog for the next 5 to 10 minutes as the water cools down and the volume of Dry Ice diminishes. As the water cools, the fog becomes wispier. Dry Ice makes fog because of its cold temperature, -109.3°F or -78.5°C, immersed in hot water, creates a cloud of true water vapor fog. When the water gets colder than 50°F or 10°C, the Dry Ice stops making fog, but continues to sublimate and bubble. The fog will last longer on a damp day than on a dry day.


For each 15-minute period put 5 to 10 pounds (2.3 to 4.5 kgs) of Dry Ice into 4 to 8 gallons (15 to 30 litres) of hot water. This will make lots of fog depending upon the temperature of the water and the size of the pieces of Dry Ice. Hotter water will make more fog. Very hot water will add its own rising steam to the vapor cloud. If there is no steam the fog will flow down hill and in the direction of any air movement. A small fan can help control the direction. Smaller pieces of Dry Ice with more surface area produce a greater volume of fog and cool the water down much faster. In both cases the result is more fog for a shorter amount of time. Keep the water hot with a hot plate, electric skillet, or some other heat source to produce fog for a longer time. Otherwise when the water gets too cold it must be replaced to continue the fog effects. If the container is completely filled with water the fog will flow over the sides the best. But the Dry Ice sublimation will vigorously bubble the water and splash it out. Even a ¾ filled container will splash some so place the container where spilled water will not ruin anything. The water vapor fog will also dampen the area it flows across. Be careful because after some time floors do get slippery.


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