Fireworks inspire a certain kind of awe at any age, and indeed most of us have at some point looked over our firework selection boxes in gleeful anticipation of the colourful explosions they will create. But is there science behind those explosions? How do they do what they do? If you want to finally find out, read on.
At their base level, fireworks generally feature a paper or pasteboard casing filled with combustible material, often pyrotechnic stars. The latter, often simply known as stars, are pellets of a very precise composition which may include metal powders, salts or other compounds that produce a certain colour or effect when ignited.
The five basic types of ingredients found in pyrotechnic stars are a fuel (thus allowing the star to burn), an oxidiser (a usually oxygen-producing compound that supports the combustion of the fuel), colour-producing chemicals (self explanatory), a chlorine donor (provides chlorine to strengthen the colour of the flame if not already done so by the oxidiser) and a binder (as it names, a binder holds the pellet together). Mag stars (especially bright ones) are fuelled by aluminium.
Specific chemicals produce specific colours. Red is created by strontium or lithium (depending on the shade of red you want), orange by calcium, yellow by sodium, gold by charcoal, iron or lampblack and white by either titanium, aluminium, beryllium or magnesium powders (to name but a few).
In a similar manner, specific chemicals are used for specific purposes. Aluminium, for example, is a common component in sparklers, antimony is used to create glitter effects and radium would create intense green colours… if it wasn’t too hazardous to use.
Speaking of hazards, firework wheels, more commonly known as Catherine wheels, are named after the instrument of torture (the breaking wheel) which in legend St Catherine was allegedly martyred on. Not the best thing to do on bonfire night!
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