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A fireworks display is part art and part science experiment
What's in these chemical coctails?
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0703FIREWORKSAUD

Jim Lancaster, the crew chief for Gainesville's July Fourth fireworks show, talks about the safety zone needed around a major public fireworks display.

It all starts with gunpowder, but to invoke those patriotic feelings on July Fourth, a little copper, strontium, barium, iron or maybe sodium is thrown in.

"The creation of a fireworks display is truly an art form, one that has been perfected by some families for generations," according to the Maryland-based American Pyrotechnics Association's Web site.

Julie L. Heckman of the organization said gunpowder, the key ingredient, is mixed with other elements to get the desired colors.

The blends are formed into "tiny little cubes, like gum drops or little circles, which we refer to as stars, and they get loaded into casings," she said.

In putting together the fireworks, manufacturers consider the visual effects that the packaged chemicals will provide, as well as the sounds, or reports, that accompany the bursts.

Jim Lancaster, the crew chief for Gainesville's July Fourth fireworks show, said strontium gives the red colors; copper, blue colors; barium compounds, green colors; sodium, yellow and orange colors; and iron compounds, gold colors.

Strontium and copper together provide a purple color, "a hard one to get out of fireworks."

"A very fine aluminum dust or titanium dust or magnesium powder is what gives us the silver tails or silver coloring in fireworks," Lancaster said.

And the recipe for gunpowder hasn't changed much in hundreds of years. Most sources credit the discovery of gunpowder to Chinese alchemists in the ninth century.

Gunpowder is "simply saltpeter, charcoal and sulfur, and it's still the same thing we're using today," Lancaster added.

Once the materials are packed into the casing, a fuse is attached so that the device can be safely ignited.

Fireworks light up the sky in "burst patterns." The popular "chrysanthemum" creates an effect of showering stars in the shape of a sphere.

"There will be separators, typically, forming a shape inside a casing," Heckman said. "You would have the cardboard insert of the shape in the center (of the casing) and you would pack your stars or little gum drops - the pyrotechnic composition - around it.

It's how the casings are packed into a firework that determine the shape of the explosion, its height and amount of bursts.

"Each one of the little colors you see in the sky - the shell may explode and you may see like 500 lights in the sky that are red and blue, et cetera - is a pellet, star or cross about the size of your fingernail," Lancaster said.

Gainesville's traditional fireworks show is being moved this year to Laurel Park at 3100 Old Cleveland Highway, from the American Legion Paul E. Bolding Post 7 on Riverside Drive.

Lancaster, chairman of trustees with the American Legion post, works for New York-based Bay Fireworks, which is presenting the show. He also is a retired Hall County Fire Services battalion chief.

He said technicians light a gunpowder fuse inside a paper container that goes to a "lift charge" on the fireworks.

The spark on the fuse, which is about 3 feet long, travels at 50 to 60 feet per second. "It's almost an instantaneous fuse," he said.

Without the paper, in the open air, the fuse burns about an inch a second.

The shells are placed in mortars, which are set in wooden racks. Lancaster said shells 8 to 10 inches long will be used in the Gainesville show.

"Anything 8 inch and (longer) now is always fired electrically," he said. "We have electric squibs with wires to them. We run these out to a long panel that we can attach those wires to.

"We are not standing up close to those shells because of the amount of powder in them. If something does go wrong, used to (be) we were right there beside them. Now, we're 50 to 75 feet away from them."

Technicians also must provide a safe perimeter around the launching area.

"If something went terribly wrong - if a rack blew apart and turned over, if a shell went horizontally instead of vertically and exploded - it could be like throwing a hand grenade into a crowd," Lancaster said.

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