Fireworks, don't we all just love them? Over the past few years, there seems to have been a growing fascination with fireworks among Trinbagonians, especially since these items have become so readily available and affordably priced on the market. Fireworks displays have become major attractions at our Independence Day celebrations, and rocket explosions and sparkling sky formations now accompany the sound of the traditional "bamboo bursting" to ring in the New Year.

Did you ever stop to wonder, where did fireworks come from and what is the technology behind them?

There has never been any disputing, that fireworks originated in China, and like so many great things Chinese, it was created in the kitchen! It is believed that a cook accidentally created the first fireworks by lighting a mixture of three basic kitchen ingredients of the time - sulphur, charcoal and salt petre. (Otherwise known as potassium nitrate, salt petre is an ingredient used in cooking for purely aesthetic reasons, as it gives meat a nice rosy red colour.) The cook discovered that this phenomenal "black powder" mixture resulted in a colourful flame and a tremendous explosion when it was enclosed in a bamboo shoot. It was believed that the loud explosions of the "black powder" were powerful enough to deter evil spirits. Soon it was used at other events such as weddings, celebrations of victory in battles, eclipses of the moon and religious ceremonies.

The basic ingredients in "black powder", and fireworks in general, have never really changed. They comprise of a source of fuel and an oxidiser. The purpose of the fuel, quite similarly to the wax in a candle, is to provide heat. The oxidiser provides more oxygen than the atmospheric air can supply, to speed up the burning process.

But there is more to making a basic firework than putting the ingredients together.

We need good visual effects!

These result from a slower burning reaction. Pyrotechnic chemists, who are trying to create bedazzle instead of bang, don't want an explosion in fire works. They want it to burn for a bit so that it gives a good visual show. To achieve the desired effect, the size of the particles of each ingredient has to be just right, and the ingredients have to be blended together precisely.

To slow down the burning, chemists use big grains of chemicals, in the range of 250 to 300 microns (the size of a small grain of sand), and they don't blend the ingredients of the "black powder" together very well. That makes it harder for the fuel and oxidiser to combine and burn, and produces a longer and brighter effect.

For the really sparkly parts of fireworks, they use even bigger grains, roughly 1,000 microns in size, which are ignited by the "black powder" fire around them and combine with the air to burn with a majestic sparking effect.

A good example of the fuel/oxidiser/sparkle combination is the "sparkler", a type of firework made of medium-sized grains of fuel and oxidiser to get the fire going, and mixed with even bigger grains of aluminium. When ignited, those grains burn in combination with the oxygen in the air, giving off the sparks. Aluminium burning at 2,700 degrees Fahrenheit (1,500 degrees Celsius) produces golden sparklers. At hotter temperatures, up to 5,400 degrees F (3,000 degrees Celsius), the aluminium produces white sparks.

Now, what about colour?

There are other chemicals used to produce colours, but only with thanks to the fact that nature conserves energy. Energy from the fire in the basic fuel is transferred to the atoms of the colorant chemicals. That takes the electrons in those chemicals to a higher energy state. The electrons actually orbit further away from the atom's nucleus in other shells. Then, as they cool down, they move back to a lower state of energy.

But remember, nature conserves energy. Energy is never lost, it's just transferred somewhere else. As the electrons "calm down", the energy they give up is converted into radiation in the form of light. That's where the light in fireworks comes from. You actually see the colours in fireworks as they're cooling down.

The different colorant chemicals in fireworks each emit light at a specific wavelength, producing different colours: strontium produces red, copper produces blue, barium produces green, sodium produces yellow and orange. Mixing colours to produce others comes into play too. Strontium (red) plus copper (blue) equals purple.

The chemists produce little pellets of colorant chemicals (the size of say marbles) with a mixture of colorant and basic fuel. These are all blended to the right degree and with the right-sized particles so that the pellet will burn at the desired rate. Then mechanics comes into play when fireworks are strategically launched high enough to be finished burning before the pieces get back down to the ground.

And that is the science behind fireworks!!

Dangers of Fireworks

It should be noted that fireworks are potentially dangerous and need to be used in a safe, cautious and controlled manner. Indeed they are not suitable for young and inexperienced users, as there are no completely safe fireworks including the very popular sparklers and roman candles. Fireworks become hot very quickly and the most common injuries caused are burns to the hands, forearms and wrist area. In addition, many fireworks have projectile (i.e. bullet) capabilities and if used inappropriately can cause bodily harm to bystanders and even pets. In the interest of safety, therefore, it necessary to ensure that other people and pets are out of range before lighting fireworks. Perhaps their use should really be left to the experts.