Fireworks Shapes: How Do Pyrotechnicians Do That?
By Emilie Lorditch
ISNS Contributor
July 1, 2008
COLLEGE PARK, MD -- A Fourth of July celebration just wouldn’t be the all-American holiday it is without the bang of fireworks. Even though fireworks have been around for nearly a millennium, even a casual glance skyward during a modern fireworks display will make evident that the science of the explosives has made significant advances in recent years. The colors are brighter, the explosions can be perfectly timed to music, and now the shapes of the fireworks displays can be designed to include circles, hearts, stars, and even smiley faces in the sky.
Phil Grucci the pyrotechnic designer at Fireworks by Grucci, of Brookhaven, New York, explained how pyrotechnicians use fireworks to create shapes in the sky.
While the aerial shells used in firework displays can range in size from golf balls to honeydew melons, the secret to creating a “shape” firework is all in how the shell is packed. Inside the shell, a time fuse is surrounded by black powder. The next layer circling the shell is made of “stars.” The stars are a careful mixture of black powder a binding such as sugar or starch and chemicals such as carbonate to make red, magnesium to make white, or copper salts to make blue fireworks. It is how the “stars” are packed inside the shell that creates the firework's shape.
“If you cut a ring-shaped shell in half, you would see a ring,” says Grucci. “In order to create a big ring, we pack a small ring (of stars) into the shell and the black powder will spread this small ring out in the night sky as a big ring.”
Getting the firework to form and keep its shape in the air is a challenge, “It is very difficult to get the exact pressure points that will create the ring pattern,” says Grucci.
Grucci’s special effect shape shells will be used for the Opening Ceremonies of the Beijing Olympics on August 8.
To link to images to use with this story, go to: http://www.aip.org/isns/reports/2008/fireworks.jpg
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This story is provided free for media use by the Inside Science News Service, which is supported by the American Institute of Physics, a not-for-profit publisher of scientific journals. Please credit ISNS. Contact: Jim Dawson, news editor, at jdawson@aip.org.
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