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WPI Technical Theatre Handbook: Smoke and Fog
 
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Smoke and Fog

Many productions can benefit from the use of artificially generated smoke. The effect is commonly used in fire scenes, as it can add a lot of realism to a scene.

Commercially available machines are available that use a chemical fluid to generate smoke. The fog fluid is generally made out of glycol and water, making it relatively non-irritating and safe for use in a theatre setting. Machines are available with remote controls that allow smoke to be discharged with the push of a button. Also, most remotes allow control of the volume of smoke discharged. A typical smoke machine is show in figure 8.3

Figure 8.3: A Rosco Laboratories, Inc. smoke machine. WPI owns a model similar to this.
\begin{figure}\psfig{file=effects/roscosmoke.eps}\end{figure}

The smoke produced by most commercial smoke machines tends to diffuse relatively quickly. For a more low-lying fog effect, fog machines are often used. These machines use dry ice, which is solidified carbon dioxide, due to an extremely low temperature. The machines are fairly simple in construction. A large drum holds water which is heated by an electric heating element. At the top of the drum, a basket holds chunks of dry ice. This basket can be lowered into the water with an external control. The top of the drum is sealed, save for an exit point for a large hose. When the basket is lowered into the water, the dry ice sublimes, and a thick, white carbon dioxide fog is formed. This fog is heavier than air, so it tends to hug the ground as it comes out of the hose. Fog machines produce a very believable effect, and the fog produced is completely harmless. Figure 8.4 shows a typical dry ice fog machine.

Figure 8.4: A typical dry ice fog machine. Two similar foggers are owned by WPI, and often used in theatre productions.
\begin{figure}\psfig{file=effects/dryice.eps}\end{figure}

Often both smoke and fog are used together to produce a very interesting effect. As usual, it is important to not over-use either effect, as they tend to lose their impact the more that they are used.


next up previous contents index
Next: Pyrotechnics Up: Special Effects Previous: Animated Costuming   Contents   Index
Steve Richardson 2000-07-06

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