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Special Effects Science

Chemistry Behind Movie Special Effects


It isn't magic that makes movies look so cool. It's done using computer graphics and smoke and mirrors, which is a fancy name for "science." Take a look at the science behind movie special effects and stagecraft and learn how you can create these special effects yourself.

Smoke and Fog

You can make dry ice fog simply by dropping a chunk of dry ice into a cup of water.
Shawn Henning, Public Domain
Spooky smoke and fog can be simulated using a filter on a camera lens, but you get wafting waves of fog using one of several simple chemistry tricks. Dry ice in water is one of the most popular method of producing fog, but there are other methods used in movies and stage productions.

Colored Fire

Applying metal salts to a fire will allow you to produce colored flames.
Don Farrall, Getty Images
Today it's usually simpler to color fire using a computer than to rely on a chemical reaction to produce colored flames. However, movies and plays often use chemical green fire, since it's very easy to make. Other colors of fire can be made by adding a chemical ingredient, too.

Fake Blood

Fake blood (stage blood) is great for theatrical productions and Halloween.
Win Initiative, Getty Images
Gratuitous amounts of blood are inherent in certain movies. Think how sticky and smelly the set would be if they used real blood. Fortunately there are alternatives, including some you can actually drink, which probably makes life easier for movie vampires.

Stage Make-Up

Skeleton Halloween Makeup
Rob Melnychuk, Getty Images
Make-up special effects rely on a lot of science, especially chemistry. If the science behind make-up is ignored or misunderood, mishaps occur. For example, did you know the original actor for the Tin Man in "The Wizard of Oz" was Buddy Ebsen. You don't see him because he was hospitalized and replaced, thanks to the toxicity of the metal in his make-up.

Glow in the Dark

This test tube has been filled with a glow in the dark liquid.
BW Productions/PhotoLink, Getty Images
The two main ways to make something glow in the dark are to use glowing paint, which usually is phosphorescent. The paint absorbs bright light and them re-emits part of it when the lights are turned out. The other method is to apply a black light to fluorescent or phosphorescent materials. The black light is ultraviolet light, which your eyes can't see. Many black lights also emit some violet light, so they may not be entirely invisible. Camera filters can block the violet light, so all you're left with is the glow.

Chemiluminescent reactions also work for making something glow. Of course, in a movie you can cheat and use lights.

Chroma Key

A blue screen or green screen is used to produce chromakey special effects.
Andre Riemann
A blue screen or a green screen (or any color) may be used to create the chroma key effect. A photograph or video is taken against the uniform background. A computer "subtracts" that color so the background vanishes. Overlaying this image over another will allow the action to be placed in any setting.

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