Making Fireworks Colorful
Colors in fireworks are usually generated by pyrotechnic stars–usually just called stars–which produce intense light when ignited. Stars contain five basic types of ingredients.
- A fuel which allows the star to burn
- An oxidizer—a compound which produces (usually) oxygen to support the combustion of the fuel
- Color-producing chemicals
- A binder which holds the pellet together.
- A Chlorine Donor which provides chlorine to strengthen the color of the flame. Some times the oxidizer can serve this purpose.
Some of the more common color-producing compounds are tabulated here. The color of a compound in a firework will be the same as its color in a flame test (shown at right). Not all compounds that produce a colored flame are appropriate for coloring fireworks, however. Ideal colorants will produce a pure, intense color when present in moderate concentration.
| Color | Metal | Example compounds |
|---|---|---|
| Red | Strontium (intense red)
Lithium (medium red) |
SrCO3 ( strontium carbonate )
Li2CO3 ( lithium carbonate ) |
| Orange | Calcium | CaCl2 ( calcium chloride ) |
| Yellow | Sodium | NaNO3 ( sodium nitrate ) |
| Green | Barium | BaCl+ ( barium chloride ions) |
| Blue | Copper halides | CuCl2 ( copper chloride ), at low temperature |
| Purple | Potassium or Strontium + Copper | KNO3 ( Potassium Nitrate ) or SrCl+ + CuCl+ ( Strontium Chloride + Copper Chloride ) |
| Gold | Charcoal , iron, or lampblack | |
| White | Titanium , aluminium , or magnesium powders | |