Lifestyle

Putting the Fun in Fireworks

Aluminium, copper and other elements are what make the colorful displays something to celebrate.
7 July, 2017
Fireworks are a beloved cultural tradition across the world. In Hong Kong and Sydney, they light up the New Year's Eve sky, sometimes in concert with the skyscraper and city lights.
In the United States, the dazzling choreographed light shows and accompanying music celebrate the nation's Independence Day. In July, from the Eiffel Tower in Paris to the Mediterranean beaches of Nice, they mark Bastille Day.

Today's technology makes for stunning pyrotechnics. At a June celebration in Liverpool, home of the 50th anniversary party for the Beatles' "Sergeant Pepper's Lonely Hearts Club Band" release, organizers called on France's GroupeF production company to put some real Lucy in the Sky with Diamonds – and to deliver the same high-end experience they're known for at the Olympics, in Dubai, and at Versailles.

Spectators see the combustion, but what pyrotechnic professionals know is that no fireworks show happens without chemistry, and that includes the metallic elements that make displays colorful.
Aluminium is used to make the white and silver colors that twist, fall or streak across the sky. It's also the most common ingredient for making smaller, hand-held holiday sparklers. Across the fireworks rainbow, other elements are used to create the full spectrum of color. They include lithium and strontium to produce red, and calcium to create an orange glow. Sodium will appear in fireworks displays as a burst of yellow, while barium and copper, respectively, create the greens and the blues.

The deeper violets are made using potassium and rubidium, and gold is achieved using iron or charcoal. For the whites, in addition to the aluminium, displays may include beryllium, titanium and magnesium.
There are other components for special effects. Antimony is used for creating a glitter cascade when fireworks are lit or launched; phosphorus is in the mix when creating a glow-in-the-dark experience. When smoke effects are needed – particularly in special choreographed performances rather than aerial fireworks – the professionals turn to zinc. Other metals and elements serve as supporting actors to the big stars, making the volatile mix more stable while ensuring reliable combustion. These hardworking, behind-the-scenes elements include potassium and sulfur, and chlorine to help boost some metal colors.

"There is a lot of physics and chemistry involved in making fireworks," says Anne Marie Helmenstine, a scientist and writer whose work spans from the U.S. Department of Energy, to community-based science engagement that demonstrates how chemistry works in real-life scenarios. "Their colors come from the different temperatures of hot, glowing metals and from the light emitted by burning chemical compounds. Chemical reactions propel them and burst them into special shapes."
For rockets and aerial shells, the technology has evolved to include compressed-air propellants and electronic timers, but most still use gunpowder – the main ingredient in firecrackers – to launch. The digital displays include yet another chemical, a zirconium compound that ignites when heated by a wire wrapped around it. They are computer controlled and rely on software that's programmed for the show.

For the aluminium-based sparklers, manufacturers mix up a liquid coating that contains the metal dust or flakes. By dipping a wire into the thick mix, or alternately pouring it into tubes, the sparkly mix is transferred to the object. The compound is balanced so that sparklers will burn slowly rather than explode, with time to enjoy the delightful surprise before it fizzles out.

To see more spectacular fireworks displays, check out the GroupeF website.
Banner image: NKBA