The recipe for building fireworks it pretty much the same as it’s been for a millennium. All you need is a combination of fuel, oxidizer to keep the fuel burning, some chemicals that produce color (such as strontium, aluminum, or copper), and a binding agent that glues everything together.
While the stuff you pack into each shell to make the fireworks virtually remains the same, the thing that adds variety and makes each light show unique is the beautiful colors splashing on the black canvas of the sky.
But what exactly gives fireworks their amazing colors? If you’re curious to know what makes your Fourth of July light show really come to life, pyrotechnician and electrical engineer Mike Tockstein — i.e. the guy behind Pyrotechnic Innovations — gives up the secret.
In an interview with Business Insider, Tockstein explains the science of fireworks, revealing the trick that gives color to your Independence Day celebration.
The Seven Colors Of Fireworks: How Do We Get Them?
As you might expect, each of the colors that light up the sky this Fourth of July is tailored from a specific chemical — and the correspondences may be a little surprising in some cases.
For instance, yellow fireworks are made with white salt (sodium), while the yellow-colored strontium actually burns in a red hue and is therefore used in red pyrotechnical shows, says Tockstein, who this year was in charge of the Fourth of July fireworks show staged at the Los Angeles Coliseum.
Salt Makes Your Fireworks Yellow, And Other Strange Chemicals That Light Up The 4th of July Sky https://t.co/wbMy77HTiN— ScienceAlert (@ScienceAlert) July 4, 2018
Creating white fireworks requires a touch of either aluminum or magnesium, both chemicals having some of the highest burn temperatures. They also come in handy in creating lighter hues when added to other color-producing chemicals.
Green fireworks are generally made with barium nitrate, a toxic chemical that also goes into making grenades, notes Business Insider.
Meanwhile, the famous golden chandeliers owe their glittering color to carbon, one of the oldest ingredient used in making fireworks, which apparently have been around for a very long time.
According to The Chemistry of Fireworks, fireworks are believed to have been discovered by accident some 2,000 years ago when a Chinese cook mixed common kitchen ingredients and ended up with gunpowder.
The ‘Unicorn’ Of Fireworks
As it turns out, blue fireworks are the most difficult to create because “there’s kind of a physics and chemistry limitation that prevents you from getting a good blue,” explains Tockstein, who notes that the blue color of fireworks comes from copper.
“Blue is still kind of the unicorn of fireworks manufacturing. The temperature of the flame has to be very precise, otherwise you lose the coloring.”
This might convince you to appreciate blue fireworks even more, now that you know there’s an entire art behind the spectacular light show that you’re enjoying this Fourth of July.
The same copper that goes into blue fireworks can be combined with red-burning strontium to produce purple fireworks. Other creative combinations lead to even more unique colors, depending on your imagination — seriously, the sky is the limit (pun intended).
The “more artistic side of pyro” involves special effects, such as the one called “ghosting,” in which the colors appear to be moving and dancing. This is achieved by layering multiple colors one on top of the other inside the same fireworks shell, reveals Tockstein.
All in all, a large-scale fireworks show like the one you can expect at Los Angeles Coliseum tonight takes several days of prep work and “well over 10,000 pounds of equipment” to pull off, says the pyrotechnics expert.
Whatever colors light up your sky tonight, may you have a happy Fourth of July!