The science behind lancework | How lances are made.


Not only do we want you to love our beautiful lancework and amazing designs, we are going to go one step further for our customers and tell you how lances are made so you can see how each individual "light" that creates a dot in the matrix to create your picture is made.

 

What is a 'lance'?
A firework Lance is a small coloured flare or spark less fountain. They consist of a paper tube which is closed at one end. The tube is filled with colour composition and then topped with a gunpowder type prime. The prime is an easily lit composition which produces lots of heat and ensures ignition of the, more difficult to light, colour composition. Most lances are about the size and shape of a cigarette and burn with a short, stubby 50mm flame, however, this is where the similarity ends. Like all fireworks some lances are much better than others. The trick to making a really good lance is to adjust the wall thickness of the case and the chemistry of the coloured composition so that the case burns away as the lance burns down, this allows the flame to remain visible from ignition until the lance is finished and so ensures the image produced remains clear, bright and uninterupted. A good pyrotechnist also knows how to adjust the burning rates of compositions so that all the colours finish at the same time.

 

Colour production:
All firework composition contain a fuel and an oxidiser. An oxidiser is a substance which, when heated, begins to give off oxygen. Potassium perchlorate is the usual oxidiser of choice. The fuel in the composition uses the oxygen during combustion and a good deal of heat is produced. The flame temperature is around 2500C. The lance composition will also contain salts of various metals. (Common table salt, sodium chloride, is an example of a metal salt, the metal being Sodium.) The purpose of these salts is to impart colour into the flame. As the salt is heated the electrons within the molecules of salt gain energy. As the molecules leave the flame they cool down and the energy is given out again but this time in the form of light as well as heat. Each metal salt has it's own unique 'fingerprint' in the form of a specific wavelenth (or colour) of light. The light from table salt appears as an orangey/yellow or amber colour. Copper salts yield blues, Barium green and Strontium red. White is a mixture of all the colours. Intermediate colours such as lilac, orange or turqouise can be made by mixing different salts. Mixing light of different colours does not give the same results as mixing paints of different colours. Other substances are also used in lance compositions: PVC powder will give off chlorine or Hyrdochloric acid gas. This helps deepen many colours as metal chlorides are the most effective colour producers. Other substances help the flame to consume the case and prevent an ash chimney forming which would obscure the flame. Examples of fuels are shellac, red gum or copal gum.
Case filling:
Most fireworks are still produced by hand or with simple purpose built machinery. Filling the very thin lance cases is quite a problem. They are too weak to press as the cases buckle very easily. We designed and built a unique piece of equipment that fills 200 cases at once, very gently but very consistently and solidly. This helps to maintain very accurate burning times.


Quality and Variety:
The skill of the firework maker lies in getting the fuel/oxider ratio balanced for each colour, producing the correct colour, getting the case to burn away cleanly, keeping the flame size and brightness similar and making all the different colours burn at the same rate. Our lances are produced here in the UK and have been used to produce thousands of lancework images by many leading UK firework companies. Whilst not all colours are possible we do have the largest range in the world and believe the quality is second to none. Ignition from the prime is usually 100%. Low smoke lances from China have recently made an appearance and whilst reliability is less good and there isn't a proper white, they can be useful in enclosed spaces where there is no wind. The flames on these low smoke lances are very long, typically around 200mm and this produces a very  unstable, shimmering lancework image. With a little  wind to clear the smoke, we believe our lances are the clearest, brightest, most reliable and produce the sharpest lancework images possible and best of all they are made in England.


Our Scientist knows his Chemistry like we know our Fireworks!

                  

All content of www.lancework.co.uk is a copyright of Sirotechnics Fireworks Lancework division 2012.