There are two types of light in fireworks: incandescence and luminescence. These two types of light are produced in different ways.
Incandescence is the light given off by heat. As an object becomes hotter, it begins to give off increasingly powerful wavelengths of light: first infrared, then red, orange, and yellow flame. This is why extremely hot flame is blue in color. Using specific arrangements of materials and controlling the temperature of the flame, the color and duration of the flame can be changed in whatever manner is desired.
However, most of the more exotic flame colors are created with luminescence. To explain how luminescence works, some knowledge of chemistry is required. In an atom, electrons reside in shells around the nucleus. Shells closer to the nucleus have a lower potential energy, while shells farther away have a higher potential energy. As a result, it takes energy to move an electron from a ‘lower’ shell to a ‘higher’ shell. When energy (such as heat) is applied to a chemical, it is absorbed by its electrons and causes them to jump shells. The ‘excited’ electrons are unstable, however, and quickly lose the excess energy, emitting it as a photon of light. The energy of the photon determines the wavelength of light and therefore its color.
Anatomy of a Firework
All of the aforementioned chemicals can’t just be combined into a charge and set on fire to create a good firework. That’s like combining all the ingredients for a cake into a blender and turning it into a smoothie. In order for a firework to look pretty (or for a cake to look and taste appetizing) there must be a careful use of color, timing, composition, and combination of ingredients. Although the exact positioning of the components may differ depending on the shape desired, most fireworks follow this basic internal structure:
Oxygen Producer - Burning is just reaction with oxygen. If there’s no oxygen, an object can’t burn. (This is the crux of the effectiveness of fire blankets and the “stop, drop, and roll” strategy- putting out a fire by essentially “suffocating” the flame.) The oxygen producer provides the oxygen (obviously) for the components of the firework to burn.
Fuel- Something needs to provide the energy to propel the firework up into the sky before detonation. Otherwise, you’d just have an unsatisfying explosion on the ground (and a dangerous fire hazard.)
Binder- This keeps the components of the firework together neatly, as well as arranging them into the right position for the proper timing and design during detonation.
Color Producer - Made with the materials described in the previous section, these are the actual compounds we see light up in the sky to form visual effects.
Types of Fireworks
Peony is the most common firework type. It is an outwardly expanding burst of many colored points of light.
Chrysanthemum fireworks are like peonies, but the colored points of the burst leave behind trails of sparks.
The Catherine wheel (or Trompillo) is a type of firework that resembles a pinwheel. Fireworks are put on the spokes of a spinning disk and ignited. The ignited firework’s momentum causes the wheel to spin, creating a circular design through its motion. The firework is named after St. Catherine, who was sentenced to death on a breaking wheel. When she touched the wheel, it miraculously broke apart.
Willow / Kamuro are like traditional burst fireworks, but their burst leaves behind trails of sparks and falls downward, like the branches of a willow tree. Kamuro means “boy’s haircut” in Japanese and the downward-flopping branches of the firework can indeed resemble a short hairstyle.
Pattern Shells
In the firework, the powder is arranged into a particular pattern. When it is ignited, the bursts of light show up in a particular pattern. Common patterns include happy faces, hearts, and planets.
Comet / Horsetail
Unlike most fireworks, these do not leave large bursts. Instead, they have a small star that leads a long glowing trail (like a comet.)
This July 4th, impress your friends or partner with your knowledge of fireworks when you attend shows together. And if this article has sparked your interest in becoming a pyrotechnics enthusiast, remember to be safe and have a wonderful Independence Day.
SETH 41