Bring Up Fireworks—How Do We Make Colours Explode

Living in Canada, I can say that Fireworks are directly associated with Summer. Now that we are in the heart of August, we are left with one last month to enjoy the rest of the season. Yet, in these earlier summer months, we have been fortunate enough to enjoy many fireworks displays and that despite our current COVID-19 pandemic restrictions. More precisely, in Quebec, Canada, we have been able to enjoy firework shows on St John the Baptist Day (24 June, provincial holiday), on Canada Day (1 July, national holiday) and in many festivals taking place around the province. For instance, there is one festival in my hometown, called ‘le Festival du Lac des Nations,’ which has been held every year except for, understandably, 2020. This year’s edition of the festival was held simultaneously in theatres with a prefixed number of people possible to accommodate, and virtually. Though, for the pyrotechnic display, only the date was known; its location remained secret. Yet, the organizers made sure to publicize a list of relevant sites to ensure that everyone could enjoy the spectacle. It was an excellent formula to avoid gathering, but something was missing….its associated music. 

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Typically five Canadian provinces compete throughout this festival with fireworks that must match a preset soundtrack. Each competitor also gets evaluated based on the complexity, diversity and placements of pyrotechnic explosions. Unfortunately, uncontrollable and yet understandable circumstances have led to the calling-off of the competition this year.  Luckily, we still had an opportunity to witness fireworks as the festival had planned for one spectacular pyrotechnic event. Conveniently, the show followed the conventional approach and the fireworks followed the rhythms of a preset soundtrack. We could listen to the playlist on popular radio channels that broadcasted the event. Even though this plan seems very well organized -giving people the chance to tune in to the music, or not- meant that we had to keep in mind the wishes of everyone nearby. Having chosen a particularly well-sought site, I had to comply with my surroundings and turn off the volume. Still, I should have thought more carefully about this whole thing and brought headphones. It simply didn’t occur to me to take them since I was with friends. Anyway, I’ll know better next time. Without the soundtrack, the fireworks display was still remarkable. It for sure lived up to its name of being the biggest in Sherbrooke yet. 

During the show, we saw smiley faces, hearts, planets, and many other intricate shapes. This demonstration made me gasp at the increased complexity and diversity that pyrotechnic companies had been able to create in such a short window of time. Not only did the shapes contribute to their complexity, but also did the colours of each firework. They were able to reflect the whole visible light spectrum from red to violet and sometimes gold and even white. One can only wonder about how this is even possible. We could even consider this whole technology as magic. If only I didn’t know any better, I sure could believe it.

Anyhow, I first learnt about the formation of the different colours in elementary school. Before jumping into the nitty-gritty of the mystery, my teacher told us about the nature of fireworks. Like any fire, you first need fuel and an oxidizer. For example, in a bonfire, the wood acts as fuel and the ambient air as the oxidizer.  In the fireworks’ case, you need a much more powerful oxidizer than air which can release more oxygen to interact with the fuel. Good choices of oxidizers are chlorate and perchlorates. Fuel will typically be charcoal or sulphur. In this case, wood would not be a good fuel source since they need much more power to propel in the air and explode. However, these two alone do not explain from where the colours originate. They are, in fact, resulting from the addition of colouring salts. If you never tried burning table salts, you should. It will produce a rich yellow-orange light. This colour is a result of the combustion of sodium. Yet, even with these three elements, one thing remains. A crucial binder is required to keep all those elements glued together in the form of a pellet. Usually, the binder is a type of starch known as dextrin. 

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So, many salts (or metals) are each responsible for producing different colours of fireworks, starting with sodium that makes yellow-orange light. Still, we are missing the information about what metal is responsible for the other colours, so here is a list. Strontium produces the dark red light; lithium, lighter red; calcium, orange; sodium, (you guessed it) yellow; barium, green; copper, blue; cesium, indigo; potassium, violet; and finally, rubidium, reddish-violet. Gold and white light, though, can be created by a wide range of metals. For gold, we may use charcoal, iron and lampblack, and for white, we may decide to burn titanium, aluminum, beryllium or magnesium. Actually, you may be surprised to know that aluminum is the metal used on the sparklers to produce silver and white flames. As for the sparklers that create gold flames, we use iron. Titanium can also serve to make pure white; and ferrotitanium, bright yellow.

Colour is only one facet of the intricacy of fireworks. As mentioned previously, shapes can also play an important role. It helps bring richness to the show and wonder to the spectacle. The pattern created comes from how our fireworks are assembled together. So, creating a smiley shape is as easy as arranging the small combustible pellets to form our dearly beloved emoji. Yet, there can be instances when the science goes wrong, and the firework doesn’t display the shape intended to present. These uncertainties are the reason why we fire several copies of the same fireworks. In this case, if one doesn’t show correctly, then at least one of the others can create the desired shape.

However, even if fireworks are impressive and merit every single one of their applause, we shouldn’t try to reproduce a show in our very own backyard. Fireworks can be pretty hazardous and, if carelessly handled, can produce serious harm; sometimes, even death. We all need to remember that these pyrotechnic tools include flammable and explosive materials, and as such, can release tremendous amounts of energy, like heat. For instance, you should never ignite fireworks during a heatwave as it may trigger a forest fire. Moreover, handling fireworks might not be the only hazard that these carry. 

We should be aware that the sounds produced from the explosion are loud enough to frighten and stress both humans and animals nearby. A typical animal behavioural response to stress is to hide or flee. These behaviours could lead new parents to abandon their offspring in exchange for safety. Chemical pollution also shouldn’t be ignored. Upon explosion, the heavy metals used to produce the colours of the fireworks can escape into the environment. The release may have detrimental effects and possibly neurological impacts on both us and our surrounding fauna. For instance, some fishermen have previously observed that some fishes were distraught following fireworks, particularly antimony sulphide-based fireworks. It is wise to understand that all parts of the firework composition may involve the presence of toxic chemicals. Thus, airing on the side of caution, we should resist the temptation to fire them. Yet, this does not mean that we shouldn’t enjoy the fleeting moments when fireworks happen in our vicinity. 

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I can’t resist feeling both respect and admiration for this technology. The former comes from the power it holds that is enough to cause harm, and in consequence, we should all keep a reasonable distance from it. The latter because of the technological advances scientists helped create. Pyrotechnic shows do not only require chemists and scientists, but they also need artists. They need art to produce a marriage of shape and colours that can’t help but produce awe in anyone watching. And now, even knowing about its underlying conception, I can’t repel the idea that fireworks are just entirely magical.

I thank you infinitely for reading this post and if you would like to know more about the mysteries that surround us, please join my subscription list to keep up with my newest content. If you have any questions, please add them to the comment section and I’ll make sure to answer them as soon as humanly possible.

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