Types of Fireworks
There are three basic types of fireworks: firecrackers, sparklers and aerial fireworks. Firecrackers consist of gunpowder and a fuse wrapped tightly in a paper tube. Sparklers are made of fuel, an oxidizer, binder, and iron or steel powder. The fuel is usually charcoal. The binder is sugar or starch. The fuel and binder are mixed with water and poured into a form or a wire is dipped into it. When it dries, it is ready to light.
Components Aerial Fireworks
Before you see them burst in the sky, aerial fireworks are called shells. A shell has four parts: the container, a fuse, a bursting charge and stars. The container is simple paper and string cylinder. The fuse is what gives the shell time to propel into the sky before exploding. The bursting charge is like a firecracker inside the shell. It makes the fireworks explode. The stars are what create the beauty of aerial fireworks.
Stars are like a bunch of sparklers inside the shell. They are formed compounds that include things like antimony to create a glittery effect or calcium to deepen the color of the sparks. They can include aluminum, magnesium, iron, zinc, or steel to make sparks. Those flakes of metal heat and sometimes even burn. The pattern in which stars are organize determines the shapes you see in the sky when a shell explodes.
Multi-break shells are increasingly popular in fireworks displays. This type of shell explodes in more than one phase. Multi-phase shells create explosions like the common ring within a ring fireworks. The shells are either arranged in layers or as a shell inside a shell. The layers have different fuses, so they explode at the right time.
How Shells Are Launched
There are two ways that aerial fireworks are launched. One way is to launch the shell from a mortar. A mortar is usually a steel tube. A lifting charge that consists of black powder is put inside the mortar. When lit, the lifting charge explodes and blasts the shell out of the tube. Simultaneously, the lifting charge lights the shell's fuse.
In recent years a safer, more advanced way of launching shells has been developed. The shells are launched with compressed air instead of a lifting charge, then detonated using an electronic timer instead of a burning fuse.
How Shells Explode
When the lifting charge goes off, it lights the fuse. The fuse burns as the shell flies through the air. When the fuse burns all the way down, it ignites the bursting charge inside the shell. The bursting charge causes the shell to explode. That explosion lights the stars, which are blasted in multiple directions as they burn.
The electronic timer simply replaces the need for a fuse. When the timer hits a certain time, the bursting charge explodes and the same reactions occur.