Ever wonder what makes that sparkler burn red, or the stardust over head bloom purple and gold?
The answer is found in some fairly complex chemistry.
Fireworks makers must balance propellants, fuel, binders and color-creating chemicals in just the right way to produce the spectacular effects so familiar on the Fourth of July.
Generally, the brighter and whiter the firework, the hotter the burn of the chemical.
Often the brightest fireworks are actually burning metals, such as aluminum, magnesium and titanium.
More vivid colors may come from cooler-burning salts. And sometimes, i order to produce the desired effect, chemicals are bound in such a way as to produce a reaction while burning.
In order to get green, chemists may mix barium and chlorinated rubber in a fireworks tube. When ignited, the combustion releases chlorine, which reacts with the barium to make barium chloride, when produces a green color.
Also, a good firework is not too smoky. Chemists have to be careful to compose fireworks in such as way that as little smoke as possible is produced.
Once the chemicals are chosen and mixed, then they are placed in the shell in packets or capsules in such as way as to explode in the right order and at the right time.
Here are some of the chemicals that create the different colors you might see in the sky on the Fourth of July.
Red: Lithium salts, strontium salts
Orange: Calcium salts
Gold: A combination of iron and carbon, such as charcoal or lampblack
Yellow: Sodium compounds
Brilliant white: Magnesium, aluminum or barium oxide
Green: Barium compounds
Blue: Copper and chlorine
Purple: Strontium and copper compounds
Silver: titanium, aluminum or magnesium