Sizzling sparklers and glowing globes

Ready for a shower of sparks

Ready for a shower of sparks  

WITH THE countdown to Deepavali proceeding smoothly, it is time to stock up on those cellophane-wrapped boxes and gift packets of firecrackers that will make the nights memorable.

A constantly overcast sky, and intermittent showers during both day and night, should not act as a dampener on the festive spirit, for there is a feeling that the financial situation is in much better shape this year, than it was last year.

When it comes to firecrackers, it might be the early shoppers who might manage to buy and carry home the latest varieties introduced this season.

Those who put off buying crackers until the very last minute might be able to get products at bargain prices, but it could be only the more conventional varieties that do not produce the most spectacular sights in the night sky.

On sale, this year, are rocket crackers that will shriek across the inky-black sky, and disintegrate into a huge ball of glittering sparks that will glow brilliantly for a few seconds, before fading away into nothingness.

There are fireworks that resemble silver flying fishes as they soar upwards with a loud hiss, leaving behind a fiery trail that narrows to a dot and explodes in a flash of yellow-red flame.

Many varieties of modern fireworks are a tried and tested mixture of chemicals such as potassium chlorate, charcoal, sulphur, starch, and sugar or petroleum derivatives.

Glittering colours come from the metallic compounds as they undergo fast and fiery chemical changes. It might come as a surprise, but some of the Deepavali crackers that we light every year, have a lot in common with flares and smokescreens. Paint-grade aluminium is responsible for the glittering effect.

Spreading light and cheerfulness

Spreading light and cheerfulness  

Though we easily take for granted the multi-coloured, glowing effects that are common enough in modern fireworks, it was a long journey to the development of coloured flames and iridescent showers of rainbow-hued sparkles.

In the early years of firecrackers, manufacturers were able to produce only yellow and orange colours with the use of appropriate mixtures of steel bits and charcoal dust.

However, by the late 18th century, manufacturers had perfected the commercial production of chlorates and these gave cracker-makers the basic shades of red and green.

It took a good many years for innovators to turn out bright blue and rich purple hues. After that, it was a case of mix and match, to get the combination right, and alter the combination to improve the visual effects.

For those who look for a technical explanation, the light emitters are of two groups: Solid state emitters which depend on black body radiation, and gas phase emitters which work through atoms and molecules.

Over the years, there has been a steady advancement in the development of pyrotechnics, and it is now becoming quite difficult to guess the right combination of chemicals that the manufacturers have used, to get a particular effect. Aerial fireworks produce their luminous extravaganzas through the effective combustion of groups of small pellets, which contain all the ingredients necessary to create a particular effect.

To give one example, a red pellet could contain substances such as potassium perchlorate and strontium carbonate, besides pitch as fuel and starch as binder.

By Michael Raj A.A.

in Coimbatore Photos: K. Ananthan

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