Colored Fire - Where to Find Metal Salts
Fire Color - Source
Green - Boric acid is probably your best source of "green". Boric acid most commonly is sold as a disinfectant in the pharmacy section of a store. Copper sulfate is another metal salt that produces green fire. You can find copper sulfate, usually diluted in liquid form, in products used to control algae in pools or ponds.
White - Magnesium compounds can lighten a flame color to white. You can add Epsom salts, which are used for a variety of household purposes. I usually see Epsom salts sold in the pharmacy section of stores for use as a bath soak.
Yellow - Your usual fire will be yellow already, but if you are burning a fuel that produces a blue flame, for example, you can turn it from green to yellow by adding sodium salt, such as common table salt.
Orange - Calcium chloride produces orange fire. Calcium chloride is sold as a dessicant and as a road de-icing agent. Just be sure the calcium chloride isn't mixed with sodium chloride or else the yellow from the sodium will overpower the orange from the calcium.
Red - Strontium salts produce red colored fire. The easiest way to get strontium is to break open a red emergency flare, which you can find in the automotive section of stores. Road flares contain their own fuel and oxidizer, so this material burned vigorously and very brightly.
Purple - Purple or violet flames may be produced by adding potassium chloride to the fire. Potassium chloride is sold as lite salt or salt substitute in the spice section of the grocery store.
Blue - You can get blue fire from copper chloride. I am not aware of a widely-available source of copper chloride. You can produce it by dissolving copper wire (easy to locate) in muriatic acid (sold in building supply stores). This would be an outdoors-only type of reaction and not something I really recommend doing unless you have a little chemistry experience... but if you're determined, dissolve a piece of copper in a solution of 3% hydrogen peroxide (sold as a disinfectant) to which you have added sufficient muriatic acid (hydrochloric acid) to make 5% HCl solution.
Do you know of other sources of metal salts that can be used to color fire? If so, please add your comments in response to this post.
Comments
Thanks for the tips, I still can’t seem to get any coloured flame effect whatsoever, I’ve tried ETOH, methanol, direct sprinkling, soaking pine cones (and drying them), paper packets with the agent…nothing works. Just plain regular flames each time, not even a hint of colour. Even the commercially prepared packets don’t always seem to work. Any ideas?
Derek,
The strength of the color is dependent on the temperature of the fire. I’m still a relative novice at making fireworks but, from what I’ve read, a 2000° (F) flame will produce significantly more intense colors than the ~1700° fire typically produced by black powder. I’m not sure how hot a typical wood fire gets, but I don’t think it reaches these temperatures.
I’m not a physicist, but I believe that the reason temperature is critical is because of how the visible light is produced. When heated, the electrons in the chemical compound become excited (ionized) into a higher energy state. When the electron drops back down to a lower energy state, it emits light at a particular wavelength – which we see as a color. The catch is that it takes a fairly high energy level (ie. temperature) to ionize the material in the first place.
One side note here: Sodium produces a much brighter light than any of the other metal salts, so you have to make sure to keep any sodium contamination way from your other chemicals.
Also, if you just want to test the color that a given substance will produce, there’s an easier way than making up a whole batch of pine cones. (I don’t know how old you are, so you may need to have a RESPONSIBLE adult help with this.)
Take a small piece of thin stainless steel wire about 4″ long, bend one end into a very small loop (about a millimeter or less in diameter), then poke the other end into the eraser on a pencil. Dip the loop into the salt. (If it’s liquid, let it dry. If it’s a solid, then just try to catch a piece so it sits firmly in the loop.)
Using the pencil as a handle, carefully place the loop with the test chemical into a hot fire. The blue flame from a gas stove should be hot enough to see at least some color, but a candle or butane lighter flame probably won’t be. (Besides, the candle or lighter flame will probably be bright enough to drown out the color you’re trying to see.)
Good luck – and don’t burn the house down!!!!
Doug