Have you ever wondered what sparklers are made of?
Sparklers consist of a mixture of chemicals that are molded onto a stick or wire. These chemicals may be mixed with water to form a slurry that can be coated on a wire by dipping the sticks, or poured into a tube. Once the mixture is dried, you have a sparkler!
The three main components used in the production of sparklers are;
- an oxidizer
- a metal fuel (iron, steel, aluminum, or other metal powder), and;
- a combustible binder
Aluminum, iron, steel, zinc or magnesium dust or flakes may be used to create the bright, shimmering sparks. The metal flakes heat up until they are incandescent and glow or, at a high enough temperature, actually burn. A variety of chemicals can be added to create variation in colour or to moderate effects. The fuel and oxidizer are proportioned so that the sparkler burns slowly rather than exploding like a firecracker. Once one end of the sparkler is ignited, it burns progressively to the other end.
Oxidizers produce oxygen to burn the mixture. Oxidizers are usually nitrates, chlorates, or perchlorates. Nitrates are made up of a metal ion and a nitrate ion. Nitrates give up 1/3 of their oxygen to yield nitrites and oxygen. The resulting equation for potassium nitrate looks like this:
2 KNO3(solid) → 2 KNO2(solid) +O2(gas)
Chlorates are made up of a metal ion and the chlorate ion. Chlorates give up all of their oxygen, causing a more spectacular reaction. However, this also means they are explosive. An example of potassium chlorate yielding its oxygen would look like this:
2 KClO3(solid) → 2 KCl(solid) + 3 O2(gas)
Perchlorates have more oxygen in them, but are less likely to explode as a result of impact than are chlorates. Potassium perchlorate yields its oxygen in this reaction:
KClO4(solid) → KCl(solid) + 2 O2(gas)
The reducing agents is the fuel used to burn the oxygen produced by the oxidizers. This combustion produces hot gas. Examples of reducing agents are sulfur and charcoal, which react with the oxygen to form sulfur dioxide (SO2) and carbon dioxide (CO2), respectively.
Two reducing agents may be combined to accelerate or slow the reaction. Also, metals affect the speed of the reaction. Finer metal powders react more quickly than coarse powders or flakes. Other substances, such as cornmeal, also may be added to regulate the reaction.
Binders hold the mixture together. For a sparkler, common binders are dextrin (a sugar) dampened by water, or a shellac compound dampened by alcohol. The binder can serve as a reducing agent and as a reaction moderator.