Fireworks
In this age of digital wizardry, where one can conjure great feats of the imagination with relative ease, sometimes the old, analog displays dazzle us the most. Few things capture human attention more than pretty exploding ordinances. In the 21st century, even fireworks displays depend on computers and intricately plotted sequencings developed by algorithms. Watching a top-notch fireworks show certainly elicits awe. It’s easy to watch the complicated exhibitions and see the mark of modern technology, which makes it easy to forget that these explosions are actually old technology.
Very old technology.
Handel composed Music for the Royal Fireworks all the way back in 1749. To Handel and his contemporaries, the roots of fireworks already stretched back nearly two millennia!
Sometime during the Han Dynasty in China, people discovered a bamboo stalk tossed into a fire produced a nice exploding pop. The quick-growing plant traps air inside its tube-like structure, which releases a nice sound when burned. China coincidentally also happened to be the birthplace of gunpowder. These two developments provided the perfect ingredients and schematics for fireworks – explosives, tubes, and loud sounds – so it’s no surprise that the Chinese developed baozhu or baogan, interchangeable terms for exploding bamboo or proto-firecrackers made of gunpowder and small containers. The Han Dynasty ruled from 202 BC to 220 AD! By the end of the era, they had developed bianpao, which translates roughly to “whip cannon,” a type of clustered firecracker that might be at home in the arsenal of many modern pyrotechnic connoisseurs.
Researchers peg anything resembling modern fireworks to have evolved in China by the Song Dynasty, which transpired between 960 and 1279. Fireworks were so revered in China that, by this point, being a pyrotechnician had become an independent profession.
Nearly anyone can blow something up, but the Chinese were equal parts artists and engineers. They discovered fireworks could become colorful by adding specific chemicals to their gunpowders. Early, they realized they could produce silver sparkles, but later began to add arsenical sulfide for yellow, copper acetate for green, lead carbonate for lilac-white, and mercurous chloride for white.
By the 14th century, firework mania had spread to Europe and we’ve been hooked ever since.
Despite the myriad advances over the centuries, including the abundant usage of computers for intricate displays, the metaphorical nuts and bolts of fireworks remain largely unchanged.
The container, known as a shell, is placed inside a tube, called a mortar. Inside the shell is a carefully curated set of components. The substance that makes the shell soar is black powder, a version of gunpowder, composed of fuel and an oxidizer. In a basic shell, two compartments are filled with black powder. The first is called the lift charge, which sends it aloft. The second is the burst charge, which ignites in the sky and sends forth a fusillade of pyrotechnic stars. These stars are the stars of the show, small pellets composed of metals and salts that morph into light and sound. Making the whole shebang work is a duo of fuses. Starting outside the shell, an operator lights the first fuse which travels to the lift charge; when the shell takes flight, a secondary timed fuse becomes active, which makes the stars combust.
Today, computers can not only light the fuses at particular instances, but they can plan precise heights in the air at which the stars can produce maximum artistic effect.
Chemistry teachers around the world love to tout the saying: “What in the world isn’t chemistry?” Fireworks are a prime example. Over the years, we have refined the ROYGBIV palette of fireworks thanks to a litany of chemicals:
Red – Strontium and Lithium
Orange – Calcium
Yellow – Sodium
Green – Barium
Blue – Copper
Indigo – Cesium
Violet – Potassium and Rubidium
Additionally, we can suss gold out of charcoal, iron, and a substance called lampblack. Titanium, aluminum, and magnesium create brilliant shades of white.
Interestingly, sparks are limited to just several colors: red/orange, yellow/gold, and white/silver. This limitation stems from how light emits from incandescent solid particles (the other colors are actually vapor phases of flames). Solid particles emit light through black-body radiation and can only produce those few hues.
The shapes of the shells and the arrangement of the stars can completely alter the way a firework appears in the sky. We have fancy names for the shapes, such as chrysanthemum, kamuro, peony, and time rain.
As gorgeous as fireworks can be, they are not without their detractors, who tout legitimate concerns.
Recently, the plight of pets has risen in the public consciousness. Communities across the globe fill with tales of frightened dogs. Though the canines get all the attention because they are more visible and audible with their disdain for the explosions, cats suffer just as much. And, of course, the consternation doesn’t apply only to indoor animals. Birds, in particular, do not do well with nighttime light and loud noises. Studies have shown that some birds will abandon nests in proximity to fireworks.
Further, environmental concerns warrant examination. These days, any unnecessary gases or smoke added to the air is far from beneficial. Is it really worth putting a lot of barium and rubidium into the outdoors? One side of the argument states the pollutants expelled by fireworks might be the result of a practice without practical benefits, but they pale in comparison to the emissions of automobiles, power plants, etc. On the other hand, even small amounts of heavy metals entering the water system can have serious impacts on ecosystems or human consumption.
To top it all off, some states or nations have banned non-governmental usage of fireworks for another reason: wildfires. As forests continue to feel the impacts of heightened droughts, gender reveal parties get the largest share of ridicule, but any incendiary device could spark a massive conflagration. In 2018, U.S. fire departments reported 19,500 blazes caused by fireworks. Nearly 60% of those fires were in brush, grass, or forests.
As with most things in life, the clearest path seems to be one of moderation.
Go easy on the neighborhood and its pets at 2 AM. Don’t set off fireworks by your local stream, lake, or river. Go wild at the displays in hundreds of municipalities across the world. They are a wonder to behold.
And, remember, it might be funny to hold a lighted Roman Candle from your rear end, but(t) just because fireworks are termed “low explosive pyrotechnic devices” doesn’t mean they can’t take off a digit or a limb.
Further Reading and Exploration
Science and civilization in China. Volume 5. Chemistry and chemical technology. Part 7: Military technology; the gunpowder epic by Joseph Needham
The Science of Fireworks – Ontario Science Centre
TYPES OF FIREWORKS EFFECTS – Keystone Fireworks
Still Up in the Air: The Environmental Impact of Fireworks – Earth.Org
