The very first fireworks — which, according to legend, were created by accident by a Chinese chemist trying to dispose of some minerals in his fire — and all fireworks for centuries afterwards were one identical color: yellowish orange. It might be difficult to imagine a monochrome fireworks display, as these days we are so accustomed to a dazzling rainbow of exploding lights, booming and brightening the night sky on most major holidays. Yet, colorful fireworks are a remarkably modern invention, invented and first available only in the 1830s thanks to Italian firework manufacturers.
Creating a colorful firework isn’t as easy as filling the tube with colored pigments or adding dyes to the gunpowder. Rather, fireworks gain their hue through specific chemical reactions, which occur when the firework explodes. There are many different elements used to make different colors, and you might be interested to learn more about how the colors in your mortar fireworks are made.
White might seem like the default color for fireworks, but as explained above, fireworks were originally orange, which means manufacturers do need to add special minerals to create electric white and light gray fireworks. The most common additive for white fireworks is magnesium, which is super-heated to produce a white explosion, but manufacturers can also use titanium and zirconium as well as barium oxide.
The reds in fireworks are produced almost entirely by the element strontium, which has other applications within oil and gas production as well as in the creation of ceramic magnets. The brightest reds rely on strontium carbonate, but strontium salts are effective as well. Because strontium can have some negative health impacts, some eco-friendly fireworks are moving toward using lithium as a replacement for strontium, but the effect is less vibrant.
Fireworks turn green due to the introduction of barium, which otherwise is not a particularly useful element as it is used somewhat in oil and gas drilling and otherwise as a pigment in paints and glassmaking. Like strontium, barium is toxic in large quantities, but the fireworks industry has yet to find a suitable replacement for producing green sparks.
To make orange fireworks that are clearly orange, not a dark yellow, fireworks manufacturers of today tend to add calcium into their chemical mix. Calcium salts, calcium chloride and calcium sulfate are all useful compounds for increasing vibrancy of the orange hue.
Blue is widely regarded amongst pyrotechnic engineers as the most difficult color to produce in fireworks. Though various copper compounds can create explosions in a range of blue shades, the problem is that many blue tones do not contrast well with the dark blue of the night sky. Thus, most blue fireworks are also very slightly green. One of the more interesting copper compounds used in fireworks is copper acetoarsenite, which produces the well-known hue of Paris Green.
In contrast to blue, yellow is perhaps the easiest firework color to create. Without careful mixing of compounds, all fireworks tend toward yellow because even trace amounts of sodium compounds can overwhelm other colors to produce a yellow explosion.
While most firework colors require specific elements or compounds to produce, purple is merely a blend of the elements used to create blue and red: copper and strontium. Of course, the combination of these compounds must be carefully measured, or else manufacturers will end up with a purplish red or a purplish blue rather than a true purple.
Some fireworks appear as a sparkling silver color, but in truth, they tend to be white fireworks with special glittery effects. Including powder or larger flakes of aluminum, titanium or magnesium will cause them to ignite during the explosion, and as they burn they tend to fizz and flash, producing a silver-like shine.
As with silver, gold fireworks tend to appear gold only because they are twinkling in a particular way. Interestingly, gold fireworks tend to use materials that have long been used in burning things, like carbon, charcoal and lampblack. During the explosion, these compounds catch fire and flicker with a golden hue.
Firework technology continues to advance, giving us access to even more spectacular light shows against the night sky. With more experimentation, we may find more ways to produce a wider range of firework hues, ensuring each fireworks display is exciting and new.