Part of the Edinburgh International Science Festival
By Freda O’Byrne
An introduction by Richard Wiseman, guest curator of the Science Festival, jokingly warned us of all the possible hazards we were possibly going to face that evening – strobe effects, asthma inducing smoke clouds, explosions, raging fires but all in the pursuit of knowledge which, of course, was what made it all worth the risks. “He’s very good, that guy” – my son commenting on Dr Wiseman’s stand up routine style introduction.
We were then handed over to Jacqueline Akhavan (Jacqui), Head of Centre for Defence Chemistry at Cranfield University where she is responsible for the delivery of education and research in propellants, pyrotechnics and high explosives together with chemical defence, fuel technology, detection, and environment impact.
Her galloping lecture started with some quick fire questions that Jacqui asked of herself to get our minds engaged. How are fireworks made ? What makes them fizzle, crack and pop? How do they produce their different colours and effects? All would be revealed, were were promised and never would we watch a firework display again without understanding what made it all happen.
I was sitting with my 14 year old son and I could see that he was immediately hooked (particularly with Jacqui being an explosives expert for the Defence Academy UK), as was I. In fact the combination of Jacqui’s charm, her very cool credentials, sense of humour and the fascination the subject held for those assembled meant that it was a very engaged audience who embarked on this particular journey of discovery.
Practical demonstrations performed by Shavi Akhavan – explosions of course of all types – illustrated the facts. What made a firework – fuel and oxygen. What made the colours? Red – potassium chlorate (KClO4 – here I get nervous in case I make an error but I understood her to say that the -ate suffix indicated that therein contained was the necessary oxygen for combustion); green – barium, white magnesium or titanium. And how do we make them crackle? I don’t know I think to myself, but I want to know. And Jacqui tells us – it is the thick oxidised coating on the titanium flakes which is burning off – it crackles, simple.
Her energetic teaching style – posing questions then offering answers, examples, anecdotes and also (most importantly to my son and his friend) demonstrations kept us engaged and focussed. She emphasised the dangers of using and working with fireworks and explosive materials. She explained how her work environment has special flooring and controlled humidity (wet towels on the radiators!) and that workers wear cotton clothing all in a bid to avoid the fatal electrostatic spark that could spell disaster.
A few questions were taken from the floor but time prevented more being answered:
How do they synch firework displays to music? By using electronic ignition and increasingly computers to control timings.
How do they make the waterfall effect? Turn a fountain fireworks upside down and allow the metal flakes that make the sparks tumble downwards.
And how do they make the hearts in the sky? By packing a firework in the shape of a heart with cylinders so that it expands outwards in the heart shape as the packets ignite.
Only an hour later we all left – entertained, educated and with not a few of us excited by this glimpse into the world of a working scientist.