Science of Fireworks: What's Behind the Different Colors of Pyrotechnics During the Fourth of July

Fireworks make celebrations extra special, and more and more people are using pyrotechnics to mark special occasions. The colorful lights that brighten the sky have something to do with the elements used.

Fourth of July Celebration: Science Behind the Fireworks' Colorful Display

The Fourth of July is among the biggest celebrations in the country, and one can expect colorful fireworks displays over the weekend. For those wondering why the lights come in different colors -- it's down to the elements used, how they react to heat, and what they produce when burned.

Red colors are caused by strontium, orange by calcium, white by aluminum, silver by magnesium, blue by copper, green by barium, yellow and gold by sodium, and purple by combining strontium and copper. Since mixing blue and red colors makes up purple, it makes sense that it takes a strontium and copper combo to have purple lights.

Fundaments of Fireworks

The fundamentals of pyrotechnics have not changed in a millennium, beginning with a formula that was thought to have been developed by Chinese alchemists in 800 CE. Three-quarters of the potassium nitrate and the remaining part of the charcoal and sulfur comprise the "black powder" they conjured up. Then, put that inside a paper container, and you have the basis for a fireworks display.

When you light that baby, the sulfur melts first, causing the charcoal and potassium nitrate to catch fire. This blaze releases an explosion of gas and energy. The fireworks shoot skyward before bursting apart if the container has a hole strategically placed to allow gas to escape.

In modern aerial fireworks, black powder is bundled into a container wired to a fuse. When the fuse is lit, the fireworks reach the "bursting charge" and burn for a predetermined period of time, during which time they reach the specified height.

Inside all that black powder are "stars," which are tiny metal salt cubes or spheres arranged in a specific design. More complex "multi-break" shells can burst in two or three phases, sometimes including shells-within-shells, fuses that ignite each other, or explosives that break each section into pieces. Exploding powder shoots those stars outward, creating intricate spheres or flowers of sparkling light with names like "palm," "willow," and "chrysanthemum."

Fireworks Safety

Fireworks are generally safe, but when mishandled, they can cause burns, eye injuries, and even hearing damage. They can also harm pets and wild animals.

It's best to leave the lighting to the pros and attend public fireworks displays. When you do, consider these fireworks safety tips.

• Observe the fireworks from afar. Keep your distance from the launch site at least 500 feet (152 meters) to avoid getting hurt or damaging your hearing.
• Do not create your fireworks.
• Avoid picking up firecracker fragments or unexploded pyrotechnics, sometimes called "duds." Some could still be on fire and blow up at any time.
• Fireworks, rockets, and sparklers are not toys, so do not play with them because they pose a risk. It's a common misconception that sparklers cause less harm than others because they can produce up to 2000°F (1093°C) heat. When contacted, this can result in severe burns as it is hot enough to melt some metals.
• Consider your pets. Due to their keen hearing, animals can become extremely anxious or scared by loud noises during major holidays like the Fourth of July. Pets should be kept inside to lessen the chance of getting lost or hurt.

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