Here are five interesting things you may not know about fireworks, courtesy of Jim Souza, President of Pyro Spectaculars by Souza.

Nearly all fireworks are handmade. If you see a fireworks show that lasts 20 minutes and has 2,000 shells (bursts in the sky) that means that 2,000 individual shells were made by hand. Most fireworks “factories” are isolated huts that are very “low-tech.”

A typical fireworks shell’s size determines three things: (a) how high up in the sky it will go before it explodes; (b) how long it will take to reach its peak height [where it will burst]; ( c ) how big a pattern it will make in the sky. A 3″ shell will rise about 300′ in about 3 seconds and will make a display about half the size of a 6″ shell.

The colors and effects are made by hundreds of “stars” inside the shell, and their exact chemical composition determines, for example, their color.

Blue is the most difficult color to display in fireworks.

Most all shows today are fired digitally, using computers and wires, but when a show is fired by hand, the fuse is called “quick match” and it burns at speeds of up to 300 feet per second!