Scotland

Big bang theory: Science meets arts for fireworks displays

Fireworks Image copyright Thinkstock

They get their colours from different metal salts, while their combination of light, shape, pace and height is an interplay of science and art.

Fireworks may have their critics but many others will be out this weekend enjoying all they have to offer.

"If I'd fired each firework one after another it would have lasted for two and half hours," explains Dave Mason, pyrotechnist and MD of Dragonfire Scotland, talking about his last show a few days ago.

"I'm now doing 10 minutes with all of this material and I'm trying to make a story, I'm trying to make something beautiful."

Image copyright Thinkstock

He is preparing for his 21st Guy Fawkes Night firing a professional show. He reckons a minute of fireworks takes about a day to complete with one person working. On the day itself more people might be rigging.

He rarely sees his shows as he chooses to fire the fireworks by hand, using a stopwatch.

"It's all overlapping," he says.

"It's layer on layer on layer. What I want is everybody in the audience to have all the hairs on the back of their neck stand up - that's it."

Image copyright Thinkstock

But if there is art in placing fireworks in the sky where you want them, you need science to help you do that, to make light and colour. In earlier times fireworks were only gold and silver, colour is a relatively new phenomenon.

"When you ignite the firework you're basically kick-starting a bunch of chemical reactions," says Dr Zara Gladman.

She works for the Glasgow Science Festival and is a contributor to BBC The Social.

The colours vary depending on which metal salt is contained in the firework. So sodium produces a yellow colour, strontium makes red, copper makes blue.

"You can combine these in the same way that an artist would combine colours painting," Dr Gladman adds.

"So strontium plus copper will produce purple. It really is a lovely example of science meets art."

Image copyright Thinkstock

But the science does not stop there. There is also the chemistry of the noise producers, the thrusters to get the fireworks up into the air. There is physics involved in modelling where debris might land.

"There's a delay that burns as this thing rises into the air, a pyrotechnic delay," says explosive consultant, Dr Tom Smith, who is secretary of the British Pyrotechnists Association.

"It then transfers the fire to what's called the bursting charge of the shell, which both lights all the stars and produces that enormous burst of colour in the sky and spreads those stars out."

And it is those bits of magic which it is all about for Dave Mason.

He says: "There are moments when you hit something and it works, you hear the audience just gasp and that to me is solid gold.

"I think we are alchemists, we take very base chemicals like charcoal and we turn it into gold inside of people."

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