Why are fireworks colored? Why do you never see blue fireworks?

Why are fireworks colorful? Why are there no green fireworks ? Let's find out together!

Humans invented fireworks for a specific reason and there is a fascinating history behind them.

The Chinese were the first to make fireworks as early as 200 BC, but they were designed to scare away evil spirits with loud noise and bright lights rather than to celebrate. The invention & use of fireworks happened quite by accident and it took more than a millennium for fireworks to be used for celebration.

Early fireworks in China were noisy and not as tightly controlled as today's fireworks.

In the 17th century, Italians discovered that bright colors like red, yellow, or white could be created by adding certain chemicals to fireworks. Since then, pyrotechnicians around the world have been trying to create 'green' fireworks effectively, but have not succeeded.

Why do fireworks have colors?

The colors in fireworks are created by metal compounds and salts, said John Conkling, a chemistry professor at the University of Washington. For example, strontium gives red, copper gives blue and magnesium gives white.

These metal compounds and salts are packed into a small bean-shaped bag, which is placed inside the firework. They are arranged into different shapes to create beautiful shapes for the fireworks when they explode, such as flowers, circles, stars, etc.

When a firework is lit, the shell is propelled into the air by a burning compound below. Once it reaches a suitable height, the shell explodes thanks to a slow-burning fuse inside.

The heat from the explosion causes the dye compounds to heat up and glow. The hotter they get, the more reactive the molecules become, creating brighter colors. But there are limits to this, as too much heat can break down the molecules and cause them to lose their color.

Why are there no blue fireworks?

However, there are some colors that are very difficult to create. Strontium chloride, the compound used to create red fireworks, can withstand temperatures of more than 800 degrees Celsius, which is hotter than lava.

But to create blue fireworks, copper chloride is needed, a much weaker compound. This compound glows blue at temperatures of about 540 degrees Celsius, but at this temperature it immediately breaks down and loses its color. Therefore, to create blue fireworks, manufacturers need to find a compound that will not break down at high temperatures and lose its color. After decades of searching, we have yet to find a suitable compound that can create blue fireworks.

Compounds required for each type of firework color

1. Red: Strontium salt, lithium salt lithium carbonate (Li2CO3).
2. Strontium carbonate, SrCO3 = bright red.
3. Orange: Calcium salts.
4. Bronze: Alloy of iron and carbon.
5. Bright yellow: Sodium nitrate compound, NaNO3.
6. White: White metals such as magnesium, aluminum, BaO salt.
7. Green: Barium and Chlorine salt compound.
8. Blue: Copper and Chlorine Compound.
9. Purple: Mixed to make red and blue.
10. Silver: Aluminum, titanium or magnesium powder.

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Micah Soto

Update 05 January 2025