The science of pyrotechnics is a fascinating and wild ride. When the shell of a firework is created, it is a careful balance of chemistry and art. Like all arts it requires relentless study and artful design. So what makes these beautiful balls of fury differ in so many colors? Well it’s all in what metal is used and the temperature that causes them to burn. Here’s a glimpse at the rainbow of pyrotechnics.
Silver
The shimmering burst in the sky, that is a staple for must fireworks is caused by burning aluminum. It’s easy to believe since the element itself is a silvery-white color. This doesn’t mean a piece of aluminum foil can be stuffed into a shell. Fireworks only work when the powder form is used. The science of fireworks requires the right blend of heat and oxygen.
Blue
Combining copper and chlorine gives a firework a blue hue. Rubber soaked in chlorine is mixed with the copper salt, the heat does the rest. This use of rubber is common in pyrotechnics.
Red
The most recognizable color on July fourth, red is achieved by burning strontium or lithium salts. Strontium is highly volatile in open air, for this reason it is often stored under kerosene. Lithium, although used more for white fireworks, can produce red at lower temperatures.
Purple
Combining the blue and red compounds will create purple.
Green
The same process used to create blue is used to create green. Rubber soaked in chloride is mixed with barium salt. Barium is a compound more commonly found in poisons. Such as rat poison.
White
Those brilliant flashes of white light can be made with lithium or aluminum, but it can also be done with magnesium. Magnesium burns so bright it can damage the eyes. It is extremely volatile around water and fire. Both will work together to make a magnesium fire worse.
Yellow
The everyday element of sodium gives fireworks their yellow color. This is of course is the metallic form of the element.
Gold
The color gold is achieved by burning a mixture of iron and carbon. This carbon could easily come from charcoal or the soot (aka lampblack) that collects around a kerosene lamp. The temperature for this color has to be very high.
Orange
Calcium salt and chloride or sulfate are mixed to make orange. The most common use for calcium chloride is ice removing salt in the winter. When around calcium sulfate, wear a mask. The compound is harsh to lungs and eyes,
Leave it to the professionals…
Only professionals should attempt to make fireworks. The compounds used can be dangerous and unhealthy. It takes an extensive study of pyrotechnics to create air show quality work. The art of firework design takes years of practice and study. Science is its cornerstone. If you’re looking for a firework show, stick with the professionals.
Further Reading:
http://geology.com/articles/fireworks/
http://scifun.chem.wisc.edu/CHEMWEEK/fireworks/fireworks.htm
http://sciencedude.ocregister.com/2009/07/02/the-colors-of-fireworks-what-is-the-secret/39861/
http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm
