From black powder to barium, music to mortars, pyrotechnics pro Jim Souza, whose company puts on the Macy's 4th of July Show in New York, explains the year-long process behind putting on a major performance.
Seconds later, a delayed fuse reaches the center of the payload, igniting the main shell to unleash a spectacle of light and sound.
Invented in ninth-century China, this mix of potassium nitrate, charcoal, and sulfur is what makes fireworks (plus guns and explosives), well, work.
This starchy stuff is often used to bind black powder and metal salts into pellets that explode into colorful stars.
As pellets containing metal salts inside the payload heat up, their electrons get excited and release excess energy as light.
In a traditional firework a lit fuse kicks off the reaction, igniting the powder in the bottom of the shell.
The all-purpose water-soluble powder is also used as a binding or thickening agent in paint, processed meats, food glazes, and envelope adhesives.
Inside the shell, the hot gases expand rapidly, building up pressure until they rip through the paper and create a loud boom.
The O2 helps the charcoal and sulfur burn too, producing hot gases that hurl the firework into the sky.
Here is what’s inside the chemical cocktail that lights up the Fourth of July sky. https://t.co/yseNE5LIi5— WIRED (@WIRED) July 4, 2019