Sparklers are sometimes called ‘snowballs’ because they have a ball of sparks surrounding the burning part of the sparkler. They do not explode. Here is a look at how sparklers work.
Comparing Sparklers With Other Fireworks
All fireworks are not the same. For example, a firecracker, a black snake, and a sparkler are very different. A firecracker creates a noisy controlled explosion. A black snake makes a snake of ash as it burns. Sparklers, on the other hand, burn over a long period of time (up to a minute) and produce a brilliant shower of sparks.
Several materials are required for a sparkler:
- Metal powder (iron, steel, aluminum, or other metal)
- Combustible binder
In addition to these components, colorants, and other compounds moderate the chemical reaction. The fuel is charcoal and sulfur, or a sparkler may simply use its binder (material used to hold the metal onto the stick) as the fuel. Typical binders include sugar, starch, or shellac. Potassium nitrate or potassium chlorate is the oxidizer. The sparks are glowing bits of metal.
Some sparkler formulas are quite simple. For example, a basic sparkler only uses potassium perchlorate, titanium or aluminum, and dextrin.
How Sparklers Work
Now that you’ve seen the composition of a sparkler, let’s consider how these chemicals react with each other:
Oxidizers produce oxygen to burn the mixture. Common oxidizers are nitrates, chlorates, or perchlorates. Nitrates consist 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 consist 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 looks 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 chlorates. Potassium perchlorate yields its oxygen in this reaction:
KClO4(solid) → KCl(solid) + 2 O2(gas)
The reducing agent is the fuel that burns in the oxygen produced by the oxidizers. This combustion produces hot gas. Examples of reducing agents are sulfur and charcoal, which react with the oxygen and form sulfur dioxide (SO2) and carbon dioxide (CO2), respectively.
Combining two reducing agents can 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. Some binders serve as a reducing agent and as a reaction moderator.
Putting it All Together
In summary, a sparkler is a chemical mixture molded onto a stick or wire. Mixing these chemicals with water makes a slurry that coats a wire (by dipping) or gets poured into a tube. Once the mixture dries, you have a sparkler. Aluminum, iron, steel, zinc or magnesium dust or flakes 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 create colors. Proportioning the fuel and oxidizer makes it 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.
Sparks cascading off of a burning stick present a burn hazard and potentially a fire hazard. The chemicals in a sparkler tend not to be highly toxic, but they aren’t edible. Sparklers should not be burned on cakes as candles or otherwise used in a manner which could lead to consumption of the ash.