Wednesday, July 04, 2007

How Do Fireworks Work?

Fireworks are thought to have originated in China some 2,000 years ago. These days, they are synonymous with our most American holiday. Americans lit off an estimated 255 million pounds of fireworks last year. "People are used to having a lot of razzle dazzle going on," said Kent Orwoll, who works for RES Specialty Pyrotechnics near Belle Plaine, Minn. His company creates the big fireworks shows like the one that helped open the new Guthrie Theatre in Minneapolis. The stuff the professionals use is much more sophisticated than what we buy at the fireworks stand. "It's mostly done electrically from quite a far distance away," Orwoll said. The professionals set up racks of mortars in which they drop each firework shell. The shell is wired to a box hooked up to a remote control. They can launch each firework with the push of a button. But how do they make those patterns in the sky like hearts, stars, and smiley faces?"They are done in a ball shell," said Orwoll. "A pattern would be put in there so if you're making a star you would have a little thing that actually looks like a star in here. The pressures are equal so when it breaks it breaks out and looks like a star or a smiley face." Different chemical compositions inside the shell create the different colors we see. So how were fireworks invented? Legend has it that fireworks were discovered or invented by accident by a Chinese cook working in a field kitchen who happened to mix charcoal, sulphur and salt-peter, all commonly found in the kitchen in those days. The mixture burned and when compressed in a bamboo tube, it exploded. Fireworks are first thought to have been used in American on July 4, 1777. Philadelphia marked Independence Day by adjourning Congress and celebrating with bonfires, bells and fireworks. The custom eventually spread to other towns both large and small.