What Makes Fireworks Change Colors?
Other People Are Reading
-
-
Since the invention of fireworks in ancient China, they have been synonymous with celebration. We see them every 4th of July in celebration of Independence Day, bursting in the sky in every major city in the world to ring in the beginning of a new year, and in both commencements and celebrations at a wide range of sporting events. Starbursts of all colors flash in the night sky and slowly fall back to earth, extinguishing before reaching their targets. Some of the most spectacular fireworks displays are the ones that burst into brilliant flowers with colors like red or blue and then gently transition to other colors as they descend.
-
In order to understand how these fireworks can change colors, we must first understand how fireworks themselves work. A single firework is comprised of a collection of components that all have to work together in order to make a successful result. The first stage is the lift charge. The lift charge is comprised of black powder, a mixture of potassium nitrate, carbon, and sulfur. One ounce of black powder is used for every pound of the firework shell to propel the shell at 180 feet per second. The lift charge ignites the break charge. The break charge is what disperses the starburst charge. The starburst charge is the collection of pellets that we see when the firework explodes. The salute, the charge responsible for the boom we hear when the firework explodes, is the last to go.
-
-
The multi-color starburst charge is primarily manufactured in Japan. The process they use generally begins with a grape seed. The grape seed is tumbled in a moistened powder mix to form the first layer. This first layer will actually be the final color seen. Once the first layer is dry, it is tumbled in another moistened powder mix to form the second layer. This is the transitionary color layer. After the second layer is dry, it is tumbled in the final mix to form the initial color layer. The powders used depend on the color transition desired. For instance to go from yellow to orange to red, the seed would first be rolled in strontium carbonate for the red layer, then calcium chloride for the orange layer, and finally in sodium nitrate for the yellow layer.
-
Some of these compounds require a binder in order to burn properly. Dextrin is a light carbohydrate most commonly made from corn and is a common binder for fireworks. Other chemicals are sometimes needed as well to get certain compounds with higher flashpoints to burn properly, for instance, a substance known as tree gum is used to get barium chlorate to burn. Barium chlorate is the powder used to make green light.
-
