The Chemistry of Firework Colors

Creating firework colors is a complex endeavor, requiring considerable art and application of physical science. The points of light ejected from fireworks, termed 'stars', generally require an oxygen-producer, fuel, binder, and color producer. There are two main mechanisms of color production in fireworks, incandescence and luminescence.

 

Incandescence

Incandescence is light produced from heat. Heat causes a substance to become hot and glow, initially emitting infrared, then red, orange, yellow, and white light as it becomes increasingly hotter. When the temperature of a firework is controlled, the glow of components, such as charcoal, can be manipulated to be the desired color (temperature) at the proper time. Metals, such as aluminum, magnesium, and titanium burn very brightly and are useful for increasing the temperature of the firework.

 

Luminescence

Luminescence is light produced using energy sources other than heat. To produce luminescence, energy is absorbed by an electron of an atom or molecule, which causes it to become excited, but unstable. When the electron returns to a lower energy state, the energy is released in the form of a photon. The energy of the photon determines its wavelength or color.

 

Quality

Pure colors require pure ingredients. Even trace amounts of sodium impurities (yellow-orange) are sufficient to overpower or alter other colors. Careful formulation is required so that too much smoke or residue doesn't mask the color. With fireworks, as with other things, cost often relates to quality. Skill of the manufacturer and date the firework was produced also greatly affect the final display.

 

Colors of Metal Salts

Red	strontium salts, lithium salts
Orange	calcium salts
Gold	incandescence of iron (with carbon), charcoal, or lampblack
Yellow	sodium compounds
Electric White	white-hot metal, such as magnesium or aluminum barium oxide
Green	barium compounds + chlorine producer (barium chloride, BaCl+ = bright green)
Blue	copper compounds + chlorine producer (CuCl = turquoise blue)
Purple	mixture of strontium (red) and copper (blue) compounds
Silver	burning aluminum, titanium, or magnesium powder or flakes

References:

1. Anne Marie Helmenstine, Ph. D. About.com Guide http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm
2. Fireworks! At SciFun@chem.wisc.edu http://scifun.chem.wisc.edu/chemweek/fireworks/fireworks.htm

 

Related Products

 

Catalog #	Product Name
C0700	Calcium Acetate Monohydrate
C0710	Calcium Carbonate
C0750	Calcium Chloride Anhydrous
C7950	Cupric Acetate, Monohydrate (Copper II Acetate)
C7952	Cupric Oxide (Copper II Oxide)
C8200-10	Cupric Sulfate Pentahydrate (Copper II Sulfate)
L2990	Lithium Chloride, Anhydrous
S3990	Sodium Acetate Anhydrous
S4000	Sodium Bicarbonate
S5000	Sodium Chloride