ColorAcademy 2005 - Fireworks

Fireworks
by Don Pavey

Firework displays of the 19th century were fine cultural experiences of a different order from those of today. They included flaming theatrical sets accompanied by the declaiming of verse and dramatic performance something like our ‘Son et Lumière’ shows. One of the 19th century fireworks displays was Pains magnificent spectacle ‘Last Pompeii’. More recently some of the spectacular effects in the Original Star Wars films were created using fireworks.

A recent display on the Thames was the Birds of Fire a sculptural experience by the French fireworks wizard, Christophe Berthonneau, a fireworks ‘choreographer’. Of the Millennium Thames fireworks display a Guardian correspondent said that the Government was sponsoring at vast expense an enormous pagan midwinter festival of dance, fire and light. This was to be an echo of the fireworks on the river Thames in 1749 on the seventh of May.
Before the last war it was possible to buy dangerous chemicals at the pharmacist, and students could devise their own many-coloured fireworks.

Colour enhanced engraving of the 1749 Thames Fireworks (British Museum)

There were even popular books to tell you how to make fireworks (See Moore below). One schoolboy was allowed by his doctor father to play with gelignite. Next door to me in his kitchen with his mother nearby, the gelignite he was grinding in a mortar exploded. I was called to get an ambulance after he had blown himself up. In the 1970s one boy who had put fireworks into his pocket was shown on TV after he had his lower trunk mutilated. For these reasons I add below a Fireworks Safety Code.

Basic gunpowder, or ‘black powder’, has been more or less the same since its invention in China. Such was the ingenuity of Chinese and Japanese fireworks that they have sometimes been described as ‘fantasques’. Black powder is also the same as that mixed by the 13th century scientist, Roger Bacon, namely: ‘saltpeter’ or potassium nitrate (75%), charcoal (15%), and sulphur (10%). That is, there has to be an Oxidiser and Fuel or reducing agent so that when heat is applied an electron-transfer or oxidation-reduction reaction takes place. As to the colours:

WHITE – For white fire the fuel needs to be a reactive metal such as magnesium to produce an incandescent white hot glow. A mixture of potassium chlorate and fine aluminium or magnesium powder produces a big explosive photoflash.

GOLD – Gold coloured sparks are produced by charcoal and iron fillings at a lesser temperature (1500 ºc).

YELLOW – Yellow orange light of a wavelength of 589 nan is emitted by sodium heated above 1800 ºc.

RED – Red is emitted by strontium hydroxide (SrOH) and strontium chloride (SrCl) at wavelengths between 605 and 682 nan. Aluminium granules added create red sparklers.

GREEN – Greens are created by the bariums, barium chloride (BaCl) gives green light between 507 and 532 nan. This is so unstable that it has to have special packing.

BLUE – A rich blue is emitted by copper chloride (CuCl) but there needs to be precise control over proportion and particle size.

PURPLE or VIOLET – Comes from strontium chloride and copper chloride which also needs careful control.

Fireworks Safety Code:

Always keep the box of fireworks closed until you take out fireworks one at a time replacing the lid immediately.
Read the instructions on each firework carefully.
Read the instructions by torchlight – never by the light of a naked flame.
Light fireworks at arm’s length – preferably with a safety firework lighter or fuse wick.
Stand well back from the lit firework.
Never return to a firework once lit – it may go off in your face.
Never throw a firework.
Never put fireworks in your pocket.
Keep pets indoors.
Never fool around with fireworks.

Bibliography

CONKLING, J.A. (1940) Pyrotechnics Scientific American. July 1990.

CONKLING, J.A. (1985) The Chemistry of Pyrotechnics. USA: Marcel Dekkler.

DIAMOND, J. (1981) Bangers and Flash London: Times. November 1st 1985.

McLAIN, J.H. (1980) Pyrotechnics from the Viewpoint of Solid State Chemistry. USA: Franklin Inst. Press.

MOORE, D.T. (1873) Pyrotechny; or, the Art of Making Fireworks at Little Cost and with complete Safety and Cleanliness.

REDHEAD, D. (1995) Fire to Paint the Sky London: Sunday Telegraph, 11th June 1995.

ROBERTS, H. (1986) Colour and Fireworks Colour Group (GB) Lecture at City University, London, 3rd December 1986.

TAKEO SHIMIZD (1988) Fireworks: The Art, Science and Technique. USA: Pyrotechnica.

VIDAL, J. (1999) One Party Rule London: Guardian September 18th 1999.