Tag Archives: chemistry

WHISTLES, HUMS AND SCREAMERS – THE CHEMISTRY OF FIREWORKS

WHISTLES, HUMS AND SCREAMERS – THE CHEMISTRY OF FIREWORKS

There are few sounds which say ‘fireworks’ more than a pyrotechnic whistle. We are all familiar with the whizzes and whoops of a firework screeching up into the night sky but what makes this effect – chemistry.

TESTING THE HOWLING WOLVES IN CHINA

It took many years to create a pyrotechnic whistle trying many different and powerful oxidisers. The first tried out was POTASSIUM PICRATE which is based around Picric Acid. The formulation was very good BUT highly volatile so was widely used in weapons and explosives. The next tried was POTASSIUM GALLATE which it turned out as even more unstable so back to the drawing board for another solution.

NEW FOR 2018 - HOWLING WOLVES #EpicFireworks

Eventually, it was determined that the most stable was SODIUM SALICYLATE which burns faster and hotter making a better whistle BUT the cheaper SODIUM BENZOATE is the more widely used in Consumer Firework production and the SODIUM SALICYTATE tends to be used by professional display companies instead as they manufacture a number of their own products.

The whistles and screeches, like in our Screaming Spiders Barrage, are made by packing the special chemical mixture into tubes (all barrages, cakes etc are all created by gluing tubes together) which will vary in size. The tube is plugged at one end and the combination of the chemicals and the compression into the tubes create the screech.

For a ‘humming’ effect, the tubes are packed in the same was as with a whistle or screech but a small angled hole is created halfway down allowing the sound to escape under pressure, creating the amusing humming or ‘wheeee’ sound.


So, there you have it. Do check out our videos for each of these effects in action for yourself.

Share

Did you know?

Did you know that fireworks including elements of all of the following disciplines:

• Chemistry
• Physics
• Aerospace engineering
• Materials sciences
• Fire science
• Psychology
• Neurosciences
• Risk management

Basically, fireworks are a clever and ancient combination of elements packed into a tube and burnt causing a chemical reaction which is dependent on the chemicals used.

Fireworks started out as being used to scare away evil spirits but soon they cottoned onto the idea that they would cause damage and were thereafter used as weapons.

Research into ‘greener’ fireworks is gathering pace as they replace some of the more noxious substances like potassium perchlorate within fireworks to Nitrogen based alternatives which they hope will retain the same impact of colours and effects without any of the toxicity issues.

The planning of a professional fireworks show is more about maths and muscle than anything else. Professional firers have to establish safety distances for each item as they can differ massively dependant on the type, size and shape of shell or mine being utilised.

Given the various scientific disciplines involved and that we are just over 6 miles from the City of Sheffield’s fantastic Hallam University, one of the country’s top ten places to study Chemistry in the UK, it is not unsurprising that we get visits from the students and their families en route. One young man, called in on his way to the Halls of Residence and collected some firework paraphernalia for his walls!

Share

History of Fireworks

Many people associate fireworks with 5th November, Diwali, Independence Day, but their original use was in New Year’s celebrations. Do you know how fireworks were invented? Legend tells of a Chinese cook who accidentally spilled saltpeter into a cooking fire, producing an interesting flame. Saltpeter, an ingredient in gunpowder, was used as a flavouring salt sometimes. The other gunpowder ingredients, charcoal and sulfur, also were common in early fires. Though the mixture burned with a pretty flame in a fire, it exploded if it was enclosed in a bamboo tube.

This serendipitous invention of gunpowder appears to have occurred about 2000 years ago, with exploding firecrackers produced later during the Song dynasty (960-1279) by a Chinese monk named Li Tian, who lived near the city of Liu Yang in Hunan Province. These firecrackers were bamboo shoots filled with gunpowder. They were exploded at the commencement of the new year to scare away evil spirits. Much of the modern focus of fireworks is on light and color, but loud noise (known as “gung pow” or “bian pao”) was desirable in a religious firework, since that was what frightened the spirits. By the 15th century, fireworks were a traditional part of other celebrations, such as military victories and weddings. The Chinese story is well-known, though it’s possible fireworks really were invented in India or Arabia.

In addition to exploding gunpowder for firecrackers, the Chinese used gunpowder combustion for propulsion. Handcarved wooden rockets, shaped like dragons, shot rocket-powered arrows at the Mongol invaders in 1279. Explorers took knowledge of gunpowder, fireworks, and rockets back with them when they returned home. Arabians in the 7th century referred to rockets as Chinese arrows. Marco Polo is credited with bringing gunpowder to Europe in the 13th century. The crusaders also brought the information with them.

Many fireworks are made in much the same way today as they were hundreds of years ago. However, some modifications have been made. Modern fireworks may include designer colours, like salmon, pink, and aqua, that weren’t available in the past. In 2004, Disneyland in California starting launching fireworks using compressed air rather than gunpowder. Electronic timers were used to explode the shells. That was the first time the launch system was used commercially, allowing for increased accuracy in timing (so shows could be put to music) and reducing smoke and fumes from big displays.

Share