Make Colored Fire in Every Color of the Rainbow

Using chemistry to color flames

Fire
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Home chemistry projects for making fire appear in different colors—whether in a fireplace, a campfire or a lab experiment—range in all colors of the rainbow: red, orange, yellow, green, blue, and violet. This project describes how you can safely create a line of fire with each of the different colors displayed in a row. In addition, you can watch a video of a colored fire rainbow, so you can see the effect of using multiple colorants.

How to Make a Rainbow of Colored Fire

There are six individual colorants for fire that can be created for home chemistry projects, and this one combines all of them to create a rainbow of fire, include six colors in the rainbow: red, orange, yellow, green, blue, and violet.

To make a rainbow effect, pour small piles of each chemical onto a heat-safe surface, such as a sheet of aluminum foil. Pour fuel across the chemicals and light one end of the "rainbow." Probably the best fuel for this effect is isopropyl alcohol because most chemicals are soluble in it. Rubbing alcohol is another good choice because the alcohol dissolves certain salts, while the water dissolves others.

However, if you are concerned about using flammable liquid alcohols, consider using hand sanitizer as a fuel. This is a gel consisting of mostly water with a smaller amount of ethyl alcohol. Hand sanitizer is safer because it doesn't spread across the surface and because it's mostly water, so it automatically extinguishes the flames. On the other hand, the display won't last as long as with other fuels.

Red Colored Fire

Red fire is produced by strontium salts, which can be found in road flares, among other places. Lithium (like from batteries) and rubidium also color flames red. This fire color is very bright.

Orange Colored Fire

You can create orange fire using a chemical you likely already have at home. Got calcium? Most calcium salts will work to make orange fire. Just make sure they are sodium-free or else you'll get a yellow flame.

Yellow Colored Fire

Yellow fire is a natural color for most fires, but it's very simple to change the color of a blue or colorless flame to yellow by adding sodium. In fact, you might accidentally make a colored fire appear yellow because any trace of sodium in the fuel can mask other colors.

Green Colored Fire

Green fire is one of the easiest colors of fire to produce. There are ten chemicals that can turn flames green, the most common of which are copper sulfate, borax, and boric acid. Both written and video instructions are available.

Blue Colored Fire

Blue fire can be produced by burning a fuel which produces a blue flame or by heating a chemical that produces blue fire, such as copper chloride. Driftwood gathered from an ocean beach often burns blue because of trace metals from seawater.

Violet or Purple Colored Fire

Purple fire is easy to make using non-toxic potassium compounds. A salt substitute is an inexpensive, readily available option. Violet or purple is a flame color that is easily overpowered by other colors, so if you want a purple fire it is best to use a blue-burning fuel for your fire, such as alcohol.

Disclaimer

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