Text structure: science 7

The Fog Thrills

1. Imagine you’re the set designer for a major Broadway production. You’re given a script about a creepy vampire that haunts a cold, damp castle. Your job is to set a dramatic scene that sucks the audience into the story. There’s a tried-and-true tool at your disposal: theatrical fog.
2. Onstage, fog is made in a couple of different ways. The type of effect you want will dictate the method you choose.

Dry Fog Ice Machines

3. Dry ice is actually frozen carbon dioxide. Regular ice is frozen water. In a dry ice machine, the solid carbon dioxide is transformed into gas and mixed with humid air, causing condensation. Internal exhaust fans then pump the fog into the room.

Characteristics of Dry Ice Fog

4. When fog is cooler than the surrounding air, it drops. This makes dry ice fog perfect for rolling across the stage or oozing down stairs. But don’t use it if a character is supposed to pass out on the floor. At lower levels, the carbon dioxide in the fog displaces oxygen in the air. Your star could end up with real breathing trouble!
5. It doesn’t hang around too long. Dry ice fog evaporates quickly as it mixes with the air, swirling nicely around your wicked villains as they move through it.

Fluid-Based Fog Machines

6. These special effect wonders form vapor by rapidly heating a mixture of water and glycol, a coolant. A nozzle forces the warm vapor out of the machine and into the cooler air to form clouds of fog.

Characteristics of Fluid-Based Fog

7. It rises as it disperses into warmer air, hanging thick and heavy overhead. Fluid-based fog is great for revealing beams of stage lighting.
8. You can control how long this fog variety lingers. Fluid-based foggers are ideal for producing thin hazes, a pea-soup atmosphere, or simulating fluffy clouds. Unfortunately, some especially sensitive performers can have allergic reactions to the chemicals in the vapor.
9. No matter which means you use, theatrical fog will surely add that special thrill (and chill!) to your next big hit.