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Fire in the sky The rockets' red glare may dazzle for a few moments, but the show takes months to prepare

While children squirm impatiently on blankets, waiting for the dusk to deepen, it seems as if the Fourth of July fireworks will never begin.

If they only knew how long fireworks really took.

The average 15-minute show has been months in the making, said Marcy Zambelli, whose family-owned Zambelli Fireworks has been lighting Independence Day celebrations since 1893.

Each brilliantly colored explosion, lasting only seconds, is the result of complex devices that take up to three weeks to make. Fired by a computer that sends pulses of electricity into their fuses in patterns choreographed to the thousandth of a second, the bursting aerial shells unfold according to a plan laid out on another computer screen weeks ago.

"There are so many elements that have to come together that you actually start the next day," said Zambelli, meaning July 5, "planning for the next year."

Despite the computers and other technological advancements, the pyrotechnic shows remain a "very primitive form of art," Zambelli said.

The basic ideas -- a chemical mixture inside a paper tube that bursts in the sky -- have been traced to China some 1,000 years ago. But Italian craftsmen are credited with adding color and showmanship in the 1700s.

"Our industry doesn't change a lot," Zambelli said. "What changes is how fireworks are being exhibited."

The individual shells, ranging in size from a tennis ball to a 12-inch sphere, are made by hand and dried in the sun, she said. Most of the shells are made in China now, but Zambelli Fireworks still makes some at its plant in New Castle, Pa.

Because of the risk that traces of pyrotechnic chemicals might be lit, resulting in an accidental fire or explosion, producing the shells relies on people power more than most manufacturing endeavors.

"We don't have any machinery," she said. "Everything is basically done by hand, from making the shells, to packing the boxes, to actually loading the trucks."

Technicians travel to the site of the show and spend up to a week setting up the racks of tubes used to launch the shells. For the upcoming holiday the company will do about 1,200 shows, she said, including displays in Philadelphia, Pittsburgh and at Seneca Nation casinos in Niagara Falls and Salamanca.

The growth of business has required hiring other workers for Independence Day and other peak times, but there's still a lot of families in the business. "It's an art taught from one person to another," she said. "The father teaches the sons, who are the helpers. As the sons get older and more experienced, they go off and take on their own displays."

No matter the complexity of the shows, some of the essential components will be the same everywhere.

The points of colored light that erupt from fireworks are called stars. When they're not ablaze, they look like dull black marbles.

Only as they burn is their beauty revealed. Traces of chemicals added to a gunpowder-like base provide the colors, with barium producing green, strontium red and copper burning blue. Stars that turn color as they fall have a core of one hue inside a coating of a second.

The stars are packed into a sphere, often filled with rice hulls or other filler to hold them in place. At the sphere's center is a tube filled with gunpowder or other chemical that will light the stars and burst the sphere, spreading them through the sky.

In the early 1990s, her company was a pioneer in the use of pattern shells, which produce the shape of a heart, a peace sign or another recognizable symbol, said Zambelli.

"Inside the shell, the stars, which are the chemicals that make the actual pattern, are put in a form that looks like a cookie cutter," she said. Then they're held in place by packing material, so when they're ignited and blown outward by the bursting charge, they keep the same shape.

But the patterns pyrotechnicians can produce remain limited, she said. Zambelli tried to produce a silver Hershey's kiss-shaped burst for the 100th anniversary of the chocolate but couldn't get it to come out right.

"Once it leaves the mortar it's on its own," Zambelli said. "It might be upside-down. The charge might have been a little heavier and distorted the shape a little bit. That's why you can't say it'll always happen perfectly."

The people who compose the shows do their best, though. Software simulations can create a decent approximation of a planned series of shellbursts, traced on an office computer screen instead of the inky night sky.

"It has the shells and size of the shell," Zambelli said, describing the fireworks show simulator. "It has the rise time and the burn time. It lets the choreographer know exactly how long it will take to leave the mortar, reach the sky, how long it'll take to open and how long it'll linger."

While computer firing works well with larger shows, most displays in Western New York will be sparked by a combination of methods. The old-fashioned way -- lighting fuses with highway flares -- is the simplest, while a growing portion of shows have some push-button electronic firing.

"We do a combination of flare and we do electrical firing, which we call manual lighting, where we push the switches," said Jim Young, owner of Young Explosives of Rochester. "Most of our shows are, if not 100 percent that way, they're 50-50."

Computer-controlled ignition is expensive, for shows that have "budgets of $100,000 to start with," said Young, whose company will do the Town of Clarence show. "There's not many of those shows around here."

What a computer does lend to a show is precision that allows the choreographer a better chance to use the shells' timing for effect, Zambelli said.

"We try to be creative with songs. Like in 'A Wonderful World,' when he says the word 'rainbow,' we light up the sky with rainbow colors. With 'red roses, too,' we put up all red shells."

Sometimes it takes a bit of experimenting to get it right. But Zambelli's Matt Wood, who was busy last week finishing the design of Philadelphia's show, doesn't mind a bit.

"It's the best job on Earth."



Working knowledge

A single six-inch shell may have several "breaks," or distinct bursts, as it rises to a peak of several hundred feet. Hard tubes packed with powder, known as spegette fuses, pass the fire from one break to the next. By varying the amount of powder in the spegette, designers can precisely adjust the delay between breaks from one to eight seconds.

A fiery five-pointed star, heart or peace symbol erupts with a bang. Chemical pellets called stars, which are packed into a plastic form filled with blast powder, explode out of a spherical shell. Sawdust or rice hulls fill the rest of the shell and hold the assembly in shape on its journey.

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