SACRAMENTO, Calif. - We've been enamored of fireworks for centuries.
Our forefathers used fireworks and black ash to celebrate events even before the first Independence Day on July 4, 1776, and the practice has held strong ever since.
But what exactly are we watching? How do fireworks, well, work?
The fireworks we'll buy at stands beginning Monday are consumer fireworks. That means there's a limit on the amount of pyrotechnic composition -- the mixture of substances that make fireworks work -- allowed, depending on the size of the firework.
"Fireworks, essentially, all work under the same principle," said William Weimer, vice president of Phantom Fireworks. "You ignite pyrotechnic composition in various forms that produce the effect."
Pyrotechnic composition is loaded into the firework, with an escape tube left open at one end. What escapes makes the fireworks' effects, he said.
Different colors and effects are the result of varying chemical combinations. Blue, for instance, is produced by a sulphur-based compound, Weimer said.
A firecracker is built on the same idea, but without the escape tube, leaving nowhere for the gas to go.
"The gas builds up and gives you the boom," he said.
While the basic principles have remained constant throughout the ages, fireworks have evolved in recent decades.
When California began allowing fireworks to be sold in the early 1960s, descriptions -- and the effects that resulted -- were all the same: "Emits showers of sparks," said Cathy Castilone, vice president of American Promotional Events Inc., a/k/a TNT Fireworks.
"They were either gold or silver and really just looked like a spray," she said. "Now, there's a variety of designs and effects like chrysanthemums or daisies and different colors -- pink, orange, greens."
A rainbow of color and variety of designs also are present in the awe-inspiring aerial fireworks that light up the sky each Fourth of July.
That crowd-pleasing happy face that bursts over Cal Expo results from a combination of stars -- the term for the individual pieces of pyrotechnic composition -- and blanks inside the firework's shell, said Eric Zeps, a licensed independent pyrotechnics operator in Sacramento.
"So you'd have two stars for eyes, several for the mouth and the rest would be something inert, like cork or rice hulls," he said.
Zeps, who has a pyrotechnics and special-effects business that does everything from Van Halen and Miley Cyrus concerts to Independence Day fireworks shows in Hawaii, explained that the designs are governed by the stars in the shell.
The shell, which can be a sphere or other shape, contains the aptly named break charge to break the shell (black powder), stars and a time fuse. The shell sits atop a lift charge (also black powder) that propels the shell, which is wrapped in craft paper and has a long fuse sticking out the end.
The firework is placed snugly into a mortar, the mechanism used to launch. Once the long fuse is lit, it quickly burns down to the lift charge, hurtling the shell out of the mortar and lighting the time fuse, he said.
The time fuse burns to the center of the shell, igniting the break charge. It bursts the shell and ignites the stars, the colorful displays that win our oohs and ahhs.
Just because they make a big bang and burst of color in the sky doesn't mean the firework itself is huge. Most of the shells are 3 to 4 inches in diameter, Zeps said.
In the realm of fireworks, it's not necessarily size that matters.
"With consumer fireworks, it's a little bit of powder in a big container," he said. "Aerial is a lot of powder, little container."
(Contact Niesha Lofing at nlofing(at)sacbee.com.)
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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