At least two thousand years ago, the Chinese invented gunpowder, a mixture of charcoal, sulfur and potassium nitrate (saltpeter). Later on the Chinese used gunpowder to make rockets and by adding an explosive charge to their rockets, the incipient form of fireworks were introduced. The ancient Chinese primarily used traditional fire crackers and exploding bottle rockets as part of their New Years celebration. While these pyrotechnic displays certainly dazzled observers in their day, they weren’t at all like the ornate patterns and brilliantly colored spectacle fireworks have become.
Around 1802, John Dalton began to lay the framework of atomic theory and the science of chemistry. Since then 92 naturally occurring elements have been discovered and defined. Certain of these elements when oxidized (reacted with oxygen, burnt) produce an exothermic reaction giving off energy in the form of heat and light. Interestingly, the color of light emitted differs depending on the element involved in the oxidation reaction. Early on when chemists were trying to discover all of the elements, they developed a technique of chemical analysis by coating a wire with a chemical and exposing it to the flame of a candle or Bunsen burner. Based on the colors they saw in the flame they could deduce pretty much what the chemical was. It was only a matter of time before someone would figure out that if you included these chemicals in fire works you could produce a colorful display.
Different colors could be produced by using combinations of the following basic elemental compounds.
BLUE – Copper oxide and other copper compounds
CRIMSON – Strontium
GREEN – Barium nitrate or chlorate and copper
ORANGE – Charcoal, iron, rubber and other carbon compounds.
RED – Strontium and Calcium Carbonate
SILVER – Aluminum
WHITE – Magnesium and aluminum or titanium
YELLOW – Calcium carbonate, deep yellow -Sodium salts
Today’s fireworks include multifaceted charges which provide a pyrotechnic extravaganza. The charge is launched to altitude with a mortar shell that also ignites the charge fuse. The main charge usually uses potassium perchlorate as an oxidizer mixed with aluminum and or magnesium, the reaction of which produces a violent explosion (characterized with a loud boom) accompanied with a brilliant flash of light. This initial explosion lights the fuse to smaller secondary charges incorporating the color causing chemicals listed above to burn. These secondary charges are propelled outward by the main charge and explode or burn with intensity seconds later producing a cavalcade of color.
Newer fireworks in recent years have included 3rd and 4th level charges, as pyrotechnic technicians become more sophisticated in designing and packaging their wares. Furthermore, my changing the shape of the charge and how it is put together, a variety of unique patterns can be achieved. The result is a dazzling display sure to inspire the ooh’s and awe’s of the crowd gathered to watch a spectacular show and full spectrum demonstration of chemical color.