How do we do that?

We’re often asked how those exploding stars in the sky appear as heart shapes, or change from one colour to another, or how we manage to get the fireworks to burst on the exact beat of a piece of music. Fireworks are often thought of as one of the black arts, a bit of sky magic conjured up by a man with a long flowing beard waving a wand. Well there are a few people in the fireworks industry still answering to that description! However the magic wand has been replaced by wireless technology and the blue touch paper by an electrical impulse. But while the displays you see today are very much part of the new digital age their roots are firmly grounded in an ancient discovery in China, the explosive mix that became known as gunpowder.  No-one is quite sure how it came about but the most likely explanation is that someone in 10th China, possibly while cooking, noticed the violent reaction when bringing a meat preservative such as Potassium Nitrate into contact with an open fire.

Before long this alarming effect was being used to ward off evil spirits and the Chinese cracker was born. Gunpowder’s constituents of Potassium Nitrate (75%), Sulphur (10%) and Charcoal (15%) were soon established and its use for military purposes gradually spread west. It took a few more centuries for the formula to be used as an entertainment in Europe. Italy is credited with this development and is still recognised today as a world leader in the pyrotechnic art.  Instead of blue touch paper, computer systems like the American FireOne can be programmed to fire effects with millisecond precision.

If we are designing to music we start with a soundtrack which we know works well with fireworks. This may include lyrical references to shapes or patterns which we can reproduce. Fireworks can produce many patterns including this popular heart shapeWhen we did a show to celebrate Simply Red singer Mick Hucknall’s 50th birthday, he chose ‘Happy Heart’ by Andy Williams as one of his favourite songs. During that sequence we included special fireworks which burst as red hearts (see photo) in the sky. For Coldplay’s ‘Fix You’ when Chris Martin sings ‘Lights will guide you home’ the sky clears to reveal clusters of twinkling lights floating across the sky suspended by parachutes.

When we put on Europe’s largest show of the decade in 2007, celebrating the 800th birthday of the City of Liverpool, the beats of ‘Sergeant Pepper’s Lonely Hearts Club Band’ were accompanied by eruptions of coloured stars each of which had been programmed to lift in perfect time with the music. We are able to design our shows with such precision thanks to computerised firing systems such as the American-made FireOne.

Here we are able to import a chosen soundtrack, see it as timeline and then mark on it the points at which we want a particular firework to ignite. To do this accurately and with split-second timing we have to know how long a firework takes to travel into the air before bursting. So if we want it to burst on, for example, those double beats of James Brown’s ‘I Feel Good’, where he sings ‘so good – beat-beat – so good’ we have to back-time the ignition time by the few seconds it takes those two fireworks (in this case the ones we use are aerial fireworks known in the industry as shells) to reach the peak of their flight and explode.

When the design is complete it is loaded directly into the firing system ready for the show. The soundtrack is also marked with all the ignition points (time-coded) and either given to the PA operator on CD or taken to the show on a laptop. Once we have set up everything on site and connected the PA equipment, the computerised firing system awaits to receive the time-coded signal. At show-time the music is started by either the laptop or the PA system and is played out of one channel whilst sending the time-coded signal out of the other. The signal can be sent either wirelessly or down a wire to the computer and in turn sends electrical impulses which ignite the tiny little match-heads in the fireworks.

Each one of the fireworks we use has been hand-crafted by specialist suppliers in countries like China, Japan, Spain & Italy. Fireworks which change colour are rather like the old-fashioned gob-stopper sweets which change colour when you suck on them. Each star in the sky starts out as a ball of gunpowder with coatings of chemicals which burn with a particular colour. So a star which changes from red to blue, for example, will have strontium nitrate (which burns red) in its outer layer and a core of copper sulphate (which burns blue). When the star is ignited in the sky, you see the outer layer burning red followed by blue.

The technique by which patterns like circles, hearts and stars is produced is relatively simple. Those shapes are created in miniature using pea-sized balls of gunpowder laid flat inside a sphere of cardboard. A cone of gunpowder (called the lifting charge) is attached to the sphere and from this runs a fuse to the centre. Here a further charge of gunpowder is placed. This is called the bursting charge. The sphere (known as a shell) is then lowered down to the base of an upright, firmly secured cardboard or fibreglass tube so that it is resting on the lifting charge. The tube is staked to the ground so it is pointing into the sky. When the lifting charge is detonated the shell is projected into the sky like a bullet from a gun. Seconds later an internal fuse ignites the bursting charge which explodes the stars outwards. In the case of patterns such as a heart or a star (pictured here) the original configuration inside the shell is maintained as the stars fly outwards. Depending on where you are standing you should see the shape in all its full-on glory. Many fireworks have exotically sounding flower names (the Japanese word for fireworks is Hanabi, or fire-flowers) and so there are red peonies with silver palm cores, pink dahlias with purple pistils and silver and gold chrysanthemums. One of the latest innovations is attaching tiny paper wings to the stars so they twirl as they fall, creating the beautiful effect known as ‘wind bells’.

There are many other examples too numerous to mention here but we hope you have enjoyed reading this very brief account.  After explaining to a client that a particularly noisy and eye-catching part of his display was a sequence called ‘whistling ti-salutes’, he emailed us to say how much he would enjoy describing it to his mates in the pub that night. ‘I’ll try to slip that name into the conversation and make it look like I’m more knowledgeable than I really am!’

No matter how advanced the technology there will always remain something of the black art about fireworks.

To see how we go about staging one of our pyromusical spectaculars click on the link and we’ll take you behind the scenes of one of our biggest shows.

For another really cool insight into the technology of fireworks have a look at this: How do fireworks work? A pyrotechnics chemist explains the science behind the brilliant colors and sounds

If you need a professional firework display and would like to work with a friendly team of firework specialists call us NOW on 0845 272 3550