COLORS AND WHERE THEY COME FROM
The bright colors that occur during a fireworks display are the result of the combustion of metal salts. Commonly used are strontium carbonate (red), calcium chloride ( orange), sodium nitrate (yellow), barium chloride (green) and copper chloride (blue). The materials have to be chosen carefully avoiding ones like sodium chloride (table salt) that absorb water and would produce a fizzle rather than a sizzle. We may like the brightest reds and yellows, but firework designers say it is actually pure white and dark blues that give them the most trouble.