Why not to use crayons as colorant in candle wax
Crayons are not good candle wax colorants because the candle wicks get clogged by the pigment and do not burn well.
The sight of all the colored wax in a new box of crayons may make you want to get out your melting pot. Crayons do seem like a logical choice for coloring candles. They come in every imaginable color--one major crayon manufacturer offers 120 different colors. Crayons are inexpensive and easy to find, even at the grocery store. They melt fairly easily, as anyone who has left a box of crayons in a car on a July day can attest. In spite of all of these apparent advantages, crayons are not the best choice for coloring candles.
Consider how a candle works: a flaming wick melts wax and the melted wax acts as fuel to keep the candle burning. The wick carries the melted wax to the flame by capillary action. Anything that interferes with the capillary action of the wick will impair the ability of the candle to burn.
Crayons are colored with pigment that are not soluble. In other words, when a crayon melts, tiny particles of color are floating in the wax base. Pigment drawn up into a wick clogs the wick and the candle does not burn well because its fuel supply has been cut off by the pigment particles.
If you have a big box of crayons that you purchased especially for making candles or if you have a pile of crayons that you must get rid of, consider using them to over dip a white candle. The colored layer on the outside of the candle does not usually cause a clogged wick. There are two things you will want to consider: you should only use the same brand of crayons in any batch because different brands of crayon have different chemical compositions that affect melting point and color. Also, for an over dipping technique, you will need to melt enough crayons to fill your wax pot. That's a lot of crayons!
If using crayons to color candles appeals to you because of the wide variety of colors available, take a second look at aniline dyes. They are oil-soluble dyes derived from coal tar. The color does not separate from the wax and so the dye is drawn up into the wick with the fuel and burned. Candle dyes available at craft and candle making suppliers use aniline dyes. They are available in wax form as blocks, disks, or chips. Liquid candle dyes are oil soluble. Aniline dye in every form comes in a wide variety of colors, and colors combine well if you wish to experiment and make your own color variations. Many suppliers provide formulas for mixing specific colors.
If you are in the mood to experiment with something other than aniline dyes, you may want to try natural dyes from vegetable matter. Beets, onion skins, coffee grounds, curry powders and herbs are all possibilities for natural candle colors. Remember that candle colors must be oil soluble so that extracting color with water or alcohol will not work for coloring candles. Steeping vegetable materials in oil or melted wax will produce pastel colors for your candle making ventures.
Although crayons seem like a good choice for coloring candles, aniline dyes and natural materials allow candle makers to craft candles that are beautiful and burn well.