An array of amazing colors and unexpected designs, fireworks are truly a thing of art – and chemistry and even physics! The large aerial fireworks that audiences enjoy bursting overhead don’t look like much in the prep area. Often shaped as tall, non-descript canisters; an innocent bystander might not even recognize the mega-powered explosion just waiting to happen.
So what’s inside these large fireworks that make them turn from ugly duckling to beautiful blossom? Firework shells contain a powdery cocktail of various chemicals needed to product the desired noises, colors and designs. More intricate fireworks even have the interior divided into sections as a way to sequence the timing of the explosions once the firework hits the air.
The reports (bangs) and whistles are created with flash powder, a pyrotechnic composition made from an oxidizer and metallic fuel. The noise produces can be manipulated with the recipe of metal and oxides. Crackling sounds, sometimes called ‘dragon eggs,’ are made by adding bismuth trioxide to the flash powder. A shrieking whistle effect is made with a concoction called ‘whistle mix’ that includes Potassium Percolate, Sodium Salicylate, Red Iron Oxide and mineral oil (or melted Vaseline) in just the right amounts.
Color in fireworks is also controlled by pyrotechnic chemical compounds. For example, Copper produces blue sparks while Barium makes green sparks. For orange, pyrotechnicians use Calcium, and for yellow, Sodium. Aluminum and titanium create brilliant white effects.