ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Thursday, July 4, 1996 TAG: 9607050010
SECTION: CURRENT PAGE: NRV-1 EDITION: HOLIDAY
Fireworks explode by a single principle - controlled combustion. The colors and pattern of a firework depend on how a pyrotechnician packs a firework casing and what chemicals are used.
Black powder or gun powder - the basic ingredient in fireworks. It creates enough gas to hurl a shell hundreds of feet into the air or push a pinwheel around in circles.
Flash powder - used to make the loud "booms" that fireworks are known for because black powder explodes relatively quietly when confined in a shell. This is a prime ingredient in firecrackers.
Chemicals - some give off bright, distinct colors, which are used for visual effects.
Charcoal or iron burn a brilliant orange
Strontium salts produce a red
Barium nitrate gives off a bright green
Blue is the hardest color to make and the search for a chemical compound to produce a better hue continues even now.
Stars - small, aspirin-sized pellets that the chemical powders are pressed into. A Roman candle will contain only a few stars while an aerial shell might contain hundreds of stars, each leaving a single trail of color when the shell explodes. How a pyrotechnician packs a shell determines the pattern that will explode in the sky. For example, an oriental shell will have stars packed one layer inside another to create the beautiful flower patterns they are known for.
Mortar - a tube closed at one end that is lowered into the ground to act as a cannon for aerial shells. The pressure of the explosion and expanding gasses trapped behind the shell thrusts it high into the sky. Small fireworks can be ignited on the ground and launched without special preparations.
- Source: National Council on Fireworks Safety Inc.
LENGTH: Short : 48 linesby CNB