The colors of fireworks in the night

The colors in fireworks come from a simple source: pure chemistry. They’re created by the use of metal salts. Naturally, these salts are different from table salt, and chemistry ‘salt’ refers to any compound that contains metal and non-metal atoms. And some of these compounds produce intense colors when they burn, which makes them ideal for fireworks.

Others, like potassium nitrate, sulfur and charcoal are useful to help the fireworks burn. While nitrates, chlorates and perchlorates provide oxygen for the combustion of the fuel. Dextrin, often used as a starch, holds the mixture together. And the use of chlorine donors strengthens some colors.

Metal salts commonly used in firework displays include: strontium carbonate (red fireworks), calcium chloride (orange fireworks), sodium nitrate (yellow fireworks), barium chloride (green fireworks) and copper chloride (blue fireworks). Purple fireworks are typically a mixture of strontium (red) and copper (blue) compounds.

Then the chemicals are mixed and pressed to single stars to be loaded into a inner tube or fireworks shell. 

What happens after fireworks ignite?

After a firework ignites, a lift charge propels it into the sky. That’s just explosive black powder in a confined space that, when lit, causes a fast increase of heat and gas that can send a firework as high as 1,000 feet (300 meters) into the air.Meanwhile, a time-delay fuse burns slowly into the interior of the firework shell. Then, after about five seconds, as the shell is soaring overhead, the fuse kindles a charge that reaches the core of the firework, explodes and ignites the stars that contain the metal salts.