Fiery Fireworks

It was the 4th of July recently and if my poor Aussie knowledge stands up to the test, I think there might just have been a whole bunch of fireworks. But what are fireworks and how do they work?

Somehow, we’ve got explosions not detonating until they’re well into the sky and then they’re all pretty colours and patterns. Explosions normally tend to be pretty chaotic and “fire-coloured”, so read on to see why fireworks are different!

 

A little history

Fireworks began where so many good inventions began … China. They invented gunpowder in 900 A.D. and promptly stuffed it into bamboo stalks and threw them onto open fires. Exciting!

It didn’t take too long to move from bamboo stalks to paper and the practice of lighting them rather than throwing them onto bonfires. By the 1400s, fireworks had spread to Europe and first collected their beautiful colours during the Renaissance when some clever Italians discovered that certain metals would do the job just fine. But more on that later.

 

What’s actually in them

There are a number of seperate components to ensure the controlled nature of firework explosions.

  • First is the lift charge, or the initial fuse that’s lit at the start.
  • That lights the black powder which provides the initial boost to get the firework up and into the sky. It’s made of of 75% potassium nitrate, 15% charcoal and 10% sulphur, all held together with a binding resin.
  • There’s then a second fuse, called a time-delayed fuse, which just as it sounds, takes a set amount of time to detonate. This cool system with two different fuses allows the firework to be boosted way into the sky and away from people before exploding.
  • This lights the second lot of gunpowder, called bursting charge gunpowder which is the main explosion that you see!
  • Imbedded in this gunpowder are carefully positioned pyrotechnic stars that really do the exciting work. The pattern of where they’re put change what “shape” the firework comes out in (like flowers, waterfalls, starbursts, etc…). These stars also determine the colour of the firework!

 

So, onto the colours

The different colours are all produced from metal compounds and salts. When they burn, there’s some chemistry that goes on with electrons getting all excited … and then becoming unexcited and giving off photons of specific colours. To summarise, just view the picture!

firework-colours-2015
Different firework colours from different metals, from CompoundInterest

 

And that comes up to the conclusion of a very brief overview on firework science. I hope you’ve enjoyed it, and realise that’s there’s so much more to read about and learn. Have fun!


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