This article is an extract from our Communicare Connection - November issue, its about fireworks

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Fireworks.

My dad was a part time farmer, and owned a small holding called Laithe Farm which is on the edge of the national park on the boundary between Yorkshire, Lancashire and Derbyshire.? He was also a full-time cobbler (shoemaker).? He always arrived home from work at 5:15 pm, he would gobble his evening meal. ?So, by 5:45 pm he would be out on the farm tending to the farm animals and chickens. By 9:45 pm he would be back in the farmhouse to watch News at Ten followed by a TV show (The Invaders) and then off to bed.? His day started at 6:30 pm with a quick breakfast, and then back out to the farm for the feeding and (cleaning up), a polite way of saying mucking out. He would then be off to work by 7:45 am.? Luckily, the shoe shop was in the local village, so travel time was minimal.? My mum also had a full-time clerical job. ?She had many skills but mostly did bookkeeping and sales ledgers, and yet still found the time to do farm chores which included bookkeeping, egg cleaning & sales, prepping the poultry for sale and looking after 3 kids too, amazing. My parents were very well known in our local village because we had a farm shop which sold our produce to the village community which included the local shops & supermarkets.

It came to pass that when I was about 8 years old, I started helping my dad with some of the farm chores one of which was cleaning up old rubbish around the farm and burning it in a pile in the middle of a field.? As it was heading towards bonfire night my school chums and I asked my dad if we could use some of the old rubbish to make a small bonfire to celebrate Guy Fauks, my dad agreed and that’s where my passion for fireworks began.? From then on, every year our bonfire got larger.? Eventually it became a public event. My dad knew a lady, one of our farm shop customers that worked at Standard Fireworks as a tester. The factory at that time for safety reasons was a cluster of huts which were located on remote land (Crosland Moor) near Meltham. She would bring us large professional fireworks in big brown sacks.? They were mostly roman candles, mortars and rockets and air bombs.? She showed me how to set them up, and how to fire them safely,? I was then in my mid-teens and was very keen student.

So, from humble beginnings our bonfires became very popular in the local community? with upwards of 100 attendees.? Looking back, I wish we had made it into formal profitable ticketed event, but in those days, everything was just for fun and not profit.

After the firework shows, we ?would safely check to? make sure all the fireworks were burnt.? Any that had not fired would dismantle them to understand what the individual components did and to investigate the nature of the compositions.? In those days there was no internet the only source of information was specialist books which were few and far between.? Our farmhouse was quite large so my parents allowed me to use one of the downstairs rooms as a laboratory where I could safely conduct my experiments into the nature of fireworks and the chemistry of the compositions.? Eventually leading to me trying a few of my own designs alongside the professional fireworks.?

I never could get them to work as good as the pro fireworks, but at the time they did work quite well.? When I was in senior school, I tried to get the chemistry teacher involved in starting a pyro club, unfortunately he was not interested. ?As an alternative with some of my pals we would occasionally meetup behind the rural studies greenhouse after school hours before the gate were closed for the day. ?We held little competitions to see who could make the best bangers, I always won, apart from when some of my chums would cheat by using compositions from purchased fireworks.

After leaving senior school I stopped my experiments, organising the bonfire was becoming a big chore, and there were the rival gangs too that would like nothing better than to sneak into the field and try and prematurely light or dismantle the bonfire. My passion for pyrotechnics has never waned and as the internet began to evolve the amount of online knowledge associated with pyrotechnics began to grow too.? Having read about many of the recipes for novel compositions and having a good understanding of the ongoing global research I was able to fill my knowledge gaps.? It is an interesting fact that the UK still has some degree of innovation when it comes to large pyrotechnic shows.? The UK is still one of the leads into the research of organic chemistry for coloured fire effects.

It was not until my late forties that I had owned a property with a large garden space in which to continue my research into pyrotechnics.?

The rules and regulations for pyrotechnicians was changing to, so to become compliant, I joined the UK pyrotechnic society.?

It was amazing to meet likeminded individuals and teams that made a living from running fireworks shows. I took the new European regulation exams that were just coming into force that would allow me to organise, run fireworks shows, and transport professional fireworks around the UK.? Every year at the pyrotechnic society AGM there was an all hands on setting up of a mega firework show.? All the members joined in, and the pros were able to pass on tips & tricks needed to make an average show into something spectacular.

One of the most amazing things I ever saw was a huge drum of high-performance transparent plastic fuse cord which we looped around the periphery of a large field several times. I think we were able to make about 6 loops. We had to wait until after dark and stand in the middle of the field.? The end of the cord was connected to some type of ariel firework. I think it was a flash bang.? When the firing end of the fuse was ignited you could see the flame traveling through the tube. The speed was amazing so much that it appeared as if two complete loops instantaneously illuminated.? Within 3 seconds the flame had propagated to the end of the fuse cord and ignited the firework.? The burn rate of this fuse cord is?phenomenal with a detonation speed of 6,400?m/s.? The composition is pentaerythritol tetranitrate or abbreviated to PETN.? The trade names are "Cordtex" and "Primacord”

At some of ‘our members’ only events we had demonstrations of Hollywood style special effects consisting of gallons of diesel fuel and explosive charges combined to blow the fuel vapour high into the air followed by ignition from a hot charge. Blowing up scrap cars and throwing them high up into the air was fun too.? For safety reasons the engine blocks and gearboxes were removed before the cars were blown up. At one of the special trained members only events two of the experienced members of the team got permission to make a large quantity of flash powder. It took them several hours to make ?the composition.? For safety reasons they were full kitted out with antistatic suits head gear and respirators.?

When it was time to detonate the firework an original style hand cranked detonator with a huge pump handle was used, very nostalgic.? When it exploded it produced the most intense shockwave and light I have ever seen or heard. ?After the event we were informed by the local police and some residents several miles away that the shockwave had caused some minor issues.? The test was in the middle of the day and at the point of ignition it appeared the sun was rising for the second time in the day, followed by a shock wave that almost knocked the spectators over.?

Another official thing we did was destroy several 15-inch shells, which are now illegal to use in the UK.? The shells had been removed from pyrotechnic stores around the UK for safe disposal.? We did this by wrapping detonation cord around the circumference of the shell, on ignition? the cords explosive force cut the shells in half and scattered the contents so fast that they never ignited, it was just amazing to watch from a safe distance and see the shell contents blow away on a slow-motion camera. We were shown how explosive lenses work and how polystyrene reflects explosive shockwaves. I never realised that a flat layer Semtex placed over a leaf on a block of 1-inch-thick ?steel would make an indent of the leaf veins and its outline in the steel when the explosive detonated.

During my time in the society I met two amazing characters, Professor Syndney Sheldon the inventor of the shaped charge for disabling landmines buried several feet underground.? His love for pyrotechnics started as a teenager -living through the London blitz, on his way home from school he would collect parts from unexploded incendiary bombs and take them home to how to see how they worked.? The other chap was an ex-army explosives expert given a top-secret job to put together a quick assembly explosive device? to blow out a door, section of wall, or window frame.? At the time this was need to know and many tests on secret range were required to perfect it.? You can now watch his device in action on many media channels as it takes out one of the front windows of the Iranian ?embassy. It allowed the SAS team to get in from multiple access points and take out the hostage takers and to free the hostages, before more innocent killings took place.? The date was May the 5th 1980.

On the following pages I will give you some insight into how fireworks are made.? Please don’t try to make fireworks at home it requires special skills and training. ?You now require a home office licence to store pyrotechnic chemicals and make firework compositions. It was the UK pyrotechnic society that helped to bring about this important change to the law, which I am sure will help to ensure the UK retains its innovative ability to lead pyrotechnic research.? These days there is much government monitoring of the purchase pyrotechnic chemicals some of which can be associated with terrorist activities.

Compositions

The ingredients for making? fireworks are like baking recipes.? Changing some of the ingredient’s percentage can make very little difference while changing others can be dramatic.? Just like original baking recipes some firework compositions have remained unchanged for thousands of years.? These recipes continue to be handed down from generation to generation.? The recipe for making black powder or gun powder ?as it is sometimes called has not changed since its invention by the Chinese thousands of years ago. In its basic form it is referred to as meal powder which must be corded into different grain sizes which is dependent on its application. Even the process by which gun powder is made has changed very little since its invention.? If you are interested in learning more about the manufacture black powder, I highly recommend that you visit the Royal Gunpowder Mills at Waltham Abby.? There is an amazing museum on this site.? It was still a manufacturing explosives during the time Margaret Thatcher was prime minister.? The booster propellant for the trident missiles was manufactured on this site. It was stopped in the late eighties as it was deemed to be unsafe due to the factory being close to a highly populated area.? During the second world war they made nitro-glycerine here too.? It shipped it off site during the dead of night in special made vans with the container suspended in the middle of the van by special elastic shock chord. Luckily there were never any accidents.? If there had been each van held enough nitro to make a crater several meters deep in the road the vehicle was traveling on.

To make good quality gunpowder you need the finest ingredients, the key one being the quality of the charcoal.? These days it is mostly alder wood, and which must have minimal impurities.? To achieve this the alder trees, must be growing near a fast-flowing stream or river.? This is the reason why Waltham Abby was chosen for the site of the Royal Gunpower Mills which opened in 1735.? There are a lot of waterways and Alder tress growing along the riverbanks around Waltham Abby.? The key part of the process for making the black powder is the milling, today we use a ball milling machine.? At the Royal Gunpowder Mills huge stone mills were used.? The milling stones are massive each stone weighs several tons. The process of making the black powder is a messy process producing lots of fine toxic dust. There would have been many fatalities over the years the mills were in operation. To make the meal powder into gun powder it has be corded.? This is the process of passing the meal powder through a selection of wire mesh screens using a hydraulic press. The size of the screen holes determines the grain size.? Another simpler method is to mix a proportional amount of stearin (potato starch)? with the meal powder which has been dampened with a little water mist.? The mixture is then pressed through a metal screen of an appropriate size to produce the grains using a granite or ceramic pestle, to avoid static sparks.? The resulting grains are allowed to dry for several hours, after which it can be classified as gun powder.? The key to understanding the efficiency of gun powder is its burn rate, which is governed by the grain size and how much of the total composition is turned into hot gas at a specific burn rate.? It is the release of hot gases that produces the explosive force. The gases produced are mostly carbon dioxide, small amounts of oxides of nitrogen, sulphur dioxide and steam.

As for fireworks black powder is the most common ingredient by far used in fireworks. By adjusting the ratio of the ingredients to change the burn rate it can act like a fuse or be a rocket propellant composition.? High burn rates ?generate a lifting or pushing force for Roman Candles and ariel shells and so forth.? The two other primary components used in fireworks, they are aluminium powder mixed with an oxidiser such potassium perchlorate this composition is referred to as flash powder and is always associated with a huge bang and a very bright white light flash.? For domestic fireworks the amount of flash powder is precisely regulated due to the explosive nature of the composition.? There is a process which can convert the flash powder into what is called fluffy flash where the same explosive effect can be achieved with a smaller amount of flash powder.??The final key component are the colour effects that the fireworks produce. ?These are based around two distinct types, metal compositions and organic based metal compositions.? This is where the science of fireworks becomes interesting much research is still ongoing into new compositions and the process of manufacturing them.? To make coloured fire a compound of a metal must be burnet in the presence of oxygen, this achieved by the use of an oxidiser such as potassium perchlorate. ?There are other oxidisers which are better, but unfortunately, they can be unstable too.? To get around the inefficiency or the lack of colour during oxidation process it was discovered many years ago that a chlorine ion donated during the oxidisation reaction intensifies the wavelength or colour of the flame.? The compound that enables chlorine ion donation is a rubber-based material called Parlon.? To this day Robert Veline compositions use Parlon for coloured stars which are ?used by many aerial shell firework manufacturers.

From my prospective I love to watch? shells launched to break at great altitude to produce some amazing effects.? We have already discussed the black powder which has several functions to make a shell firework work.? To make the shell fire from its mortar tube a ?black powder fuse required. The black powder is incorporated into stringlike material with a cardboard sheath which we call quick match.? The quick match allows a rapid fire to burn down the inside? of a mortar tube to the seat of the shell where a charge of gunpowder is located.? The quick match fuse ignites the lifting charge. The amount of lift charge is critical to lift shell to a specific height where it will break.? This must be at the top of the shells travel or apogee.? When the lift charge goes off in the mortar tube and the shell begins to rise and the heat from the hot gas ignites a fuse that burns up into the centre of the shell via a small guide tube.? The time delay of this fuse must precisely match the lifting force? so that when the shell is at its apogee the burning fuse will reach middle of the shell where it ignites a compound of black powder and rice hulls, the burst charge.? The bursting charge is critical if it is two forceful there is not enough time for the starts to light as they burst out radially from the epicentre of the shell.? To aide the stars ignition there are several types of coating that can be applied to the surface of the stars, potassium dichromate was one of the common ones used by pyrotechnic researcher Robert Veline. The problem is potassium dichromate is toxic and is a known carcinogen.? If the explosive for is to low the stars will light but instead of radiating out spherically, they will drop and begin to fall away in a sort of cascade effect which for some effects would be acceptable, such as willow.? You should also know that some of the larger shells contain several hundreds of stars.

Making stars for shells.

If you have ever seen the stars from firework shells, you will know that they are mostly perfectly round.? They are easy to make although quite time consuming.? Star manufacture has not changed for hundreds of years and is mostly a manual process. The process is called rolling.? If you have ever rolled a snowball, you will know what I mean.? The same process is applied making stars. ?The composition must be of the right consistency. This is achieved by sprinkling the composition into a high sided pan or wok using a pepper pot sprinkler or similar.? On to this composition ?a small amount of alcohol is sprayed.? A reasonable number of tiny lead shot pellets are the placed in the pan.? The pan is the moved in such a way the lead shot is made to roll through the mixture.? When the pellets have taken up all the pan mixture more composition is added along with more alcohol.

As with most things there is a knack to perfecting the process.? As the stars begin to grow, it becomes possible to increase the amount of composition and alcohol or even change the composition to produce a different colour effect.? When the desired star size has been achieved, they must be coated with a special composition that will allow them to light following the release of the fire from the shells bursting charge.? Before the stars can be used, they must be slowly dried safely for several days to ensure the composition layers become rock hard.? So next time you see a shell break just remember in the centre of each shell is a tiny piece ?lead shot that was used to seed the formation of the star.? Not to worry though the heat from the final burning phase? of the star will mostly melt and vaporise the lead long before it has time to fall back to earth and pollute the environment.

I have included a few simple diagrams that give you the information about the ingredients that make up the compositions for coloured stars and what the interior of an aerial shell looks like.? Ariel shells are my favourite firework.? In the UK these days they cannot be purchased by the public.? They were banned because within one year two independent idiots decided to go and investigate the mortar tubes to see why the firework had not gone off. On both occasions when they investigated the tubes the shells launched, on both occasions they were decapitated, what a way to go. Stay safe even small fireworks in the wrong hands are dangerous, leave them to the professionals