As the United States celebrates independence this Fourth of July, fireworks displays will light up the skies. From small backyard fireworks to elaborate public displays, fireworks are a crucial part of this annual celebration.
Fireworks are used in celebrations all over the world, whether it’s New Year’s or a live concert. Have you ever wondered exactly how these complicated fireworks are organized?
Let’s explore the engineering and artistry of pyrotechnics: a science that involves producing “effects like light, sound, smoke, or heat through controlled chemical reactions,” such as fireworks.
The history of pyrotechnics begins in China between A.D. 600-900, when Chinese alchemists experimented and created the earliest form of explosive gunpowder. Mixing potassium nitrate, charcoal, and sulfur, these alchemists created a black, flaky powder that would explode when placed in small bamboo tubes.
Modern-day fireworks have remained relatively unchanged, using the same ratio of 75% potassium nitrate, 15% charcoal, 10% sulfur, but exchanging the bamboo for cardboard or paper shells. When a reaction occurs, sulfur heats up first and melts at 235 degrees Fahrenheit (113 degrees Celsius), which then causes the potassium nitrate and charcoal to burn and results in an explosive reaction. By placing a tiny hole in the shell, pressure is built up that launches the firework into the sky where it explodes.
To create the breathtaking fireworks shows we see during holidays, pyrotechnic engineers change certain aspects of this basic chemical equation to create displays of different sizes and colors. Changing the size of the powder granules changes the size of the reaction. Adding different chemical elements changes the colors.
Barium makes greens, for example, while copper makes blues. Color is released as energy in the form of wavelengths when electrons change between electron energy levels. Larger jumps in energy levels result in shorter wavelengths and different colors, with red having the longest wavelengths and blue and violet having shorter ones. Engineers often must find the precise wavelength when finding a color because certain elements, like copper, have a narrow range of wavelengths. To add colored sparks, pyrotechnic engineers add different metals, like aluminum, magnesium, and iron.
Creating displays goes beyond color and ornamentation. To create engaging shows for viewers, engineers experiment with the physical structure of the firework. Using ‘multi-break’ shells with multiple layers, shows with different timed intervals can be created. Different patterns and lights are formed by placing “stars”— mini fireworks that are arranged intentionally.
If pyrotechnics sounds interesting to you, explore becoming a pyrotechnic engineer or designer. A background in chemical engineering is often required, and depending on the state, a license may be required. Pyrotechnic engineers apply their chemical engineering background to gauge the best reactants for a reaction and how to have that reaction occur safely.
The main priority of a pyrotechnic engineer is safety. There are many requirements established by the Occupational Health & Safety Administration (OSHA) and National Fire Protection Association (NFPA), including proper site cleanup and the use of personal protective equipment. A pyrotechnic designer, however, is more concerned with the design and aesthetics of a fireworks display. To become one, specific training and certifications are required.
As America sits back to enjoy the many fireworks shows on display this weekend, think of all the engineering and artistry that goes into making these shows happen. Pyrotechnics is a unique application of chemical engineering, highlighting the versatility of the many career opportunities that engineering can provide.
Sources
https://engineeringonline.ucr.edu/blog/pyrotechnic-engineer-salary/
https://www.eit.edu.au/fireworks-art-and-science-of-pyrotechnics/
https://www.borntoengineer.com/how-do-fireworks-work-we-ask-a-pyrotechnics-chemist
