Fireworks are synonymous with celebrations, whether it's a Fourth of July event, New Year's Eve or a grand finale at an amusement park. The magic of fireworks lies in their ability to light up the sky with beautiful displays and create lasting memories.
But have you ever wondered about the science behind this magic? What are the different types of fireworks that create these mesmerizing displays? In this article, we will delve into the world of firecrackers, sparklers and aerial fireworks, as well as uncover the secrets behind their bright lights and loud noises.
Most people in the United States have experienced fireworks at some point. Two common pyrotechnic devices that many are familiar with are sparklers and firecrackers. Understanding these light consumer fireworks is key to comprehending the workings of aerial fireworks and other fireworks effects.
Firecrackers have been a part of human culture for centuries. They are made of either black powder (gunpowder) or flash powder, enclosed in a tight paper tube with a fuse to ignite the powder.
Black powder, discussed briefly in How Rocket Engines Work, consists of charcoal, sulfur, and potassium nitrate, while some compositions may include aluminum to brighten the explosion.
Sparklers, on the other hand, are very different from firecrackers. A sparkler burns over a long period of time (up to a minute) and produces extremely bright and showery light. Sparklers are often referred to as "snowball sparklers" because of the ball of sparks that surrounds the burning portion of the sparkler.
If you look at Patent #3,862,865: Sparkler composition, you can see that a sparkler consists of several different compounds:
Iron or steel powder
The fuel is charcoal and sulfur, and the binder can be sugar or starch. Mixed with water, these chemicals form a slurry that can be coated on a wire (by dipping) or poured into a tube.
Once it dries, you have a sparkler. When you light it, the sparkler burns from one end to the other (like a cigarette). The fuel and oxidizer are proportioned, along with the other chemicals, so that the sparkler burns slowly rather than exploding like a firecracker.
It is very common for fireworks to contain aluminum, iron, steel, zinc or magnesium dust in order to create bright, shimmering sparks. The metal flakes heat up until they are incandescent and shine brightly or, at a high enough temperature, actually burn. A variety of chemicals can be added to create colors.
Aerial Fireworks: Painting the Sky
Aerial fireworks are the highlight of most fireworks displays. These mesmerizing firework effects — like a floral-shaped aerial pattern, a brocade or willow effect, a spherical burst shell, a spark trailing stars, or classic aerial bursts — are usually formed as a shell consisting of four parts: a container, stars, a bursting charge and a fuse.
The container is typically made of pasted paper and string formed into a cylinder. The stars are spheres, cubes or cylinders of a sparkler-like composition. The bursting charge, similar to a firecracker, is located at the center of the shell, and the fuse provides a time delay for the shell to explode at the right altitude.
Simple shells are paper tubes filled with stars and black powder. The stars, made of sparkler compound, are poured into the tube and surrounded by black powder. When the fuse burns into the shell, it ignites the bursting charge, causing the shell to explode and the colorful stars to burn with bright showers of sparks — a very common aerial effect.
Multibreak shells are more complex and burst in two or three phases. They may contain stars of different colors and compositions to create varying effects. Some shells contain explosives designed to crackle in the sky or whistles that explode outward with the stars.
Fireworks Displays: Crafting the Patterns
The arrangement of star pellets inside aerial shells determines intricate aerial effects that paint the sky. To create a specific figure, an outline of the figure is created in star pellets, surrounded by a layer of break charge, and explosive charges are placed inside the pellets to blow them outward into a large figure.
Palm: Contains large comets, or charges in the shape of a solid cylinder, that travel outward, explode and then curve downward like the limbs of a palm tree
Round shell: Explodes in a spherical shape, usually of colored stars
Ring shell: Explodes to produce a symmetrical ring of stars
Willow: Contains stars (high charcoal composition makes them long-burning) that fall in the shape of willow branches and may even stay visible until they hit the ground
Roundel: Bursts into a circle of maroon shells that explode in sequence
Chrysanthemum: Bursts into a spherical pattern of stars that leave a visible trail, with an effect somewhat suggestive of the flower
Pistil: Like a chrysanthemum shell, but has a core that is a different color from the outer stars
Maroon shell: Makes a loud bang
Serpentine: Bursts to send small tubes of incendiaries skittering outward in random paths, which may culminate in exploding stars
Novelty Fireworks: More Than Just Lights
Novelty fireworks are designed to entertain in ways other than just producing light and sound. Some common novelty consumer fireworks include:
Smoke bombs: Produce colored smoke balls and are often used during the daytime.
Roman candles: Shoot flaming balls or stars into the air.
Bottle rockets: Small rockets that shoot into the air and may produce a report or a small burst of stars.
Ground spinners: Spin on the ground and emit colored flames and sparks.
Now That's Colorful!
Did you know that the colors in fireworks are created by adding different metal salts to the pyrotechnic composition? For example, strontium salts and barium salts produce red and green sparks respectively, and copper salts produce blue flames.