Articles

    Crayon Chemistry

    Kids, did you ever wonder what crayons are made of and how all those different colors arise? You probably know that they are "wax" crayons, but let¹s go a little bit deeper than that. Waxes are a mixture of chemicals called esters, fatty acids, alcohols and hydrocarbons. They are for the most part natural substances and are either "animal, vegetable or mineral" in origin. There are many different kinds such as beeswax (animal), carnauba (plant), and candelilla (plant). And then there is paraffin, obtained from petroleum (or "mineral"), from which crayons are made. Paraffin in chemical terms is a straight chain hydrocarbon: one molecule has 26-30 carbon atoms in a row with 2 or 3 hydrogen atoms attached to each. Add a little color (dye or pigment) and presto, you have a crayon.

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    We urge you to visit a fantastic crayon empire called The Crayola Factory in Easton, PA (610-515-8000) where you can watch crayons being made. The paraffin is delivered to them in heated tanker-train cars and stored in two-story silos. When needed, the wax is pumped into large, heated kettles and mixed with pigment. This crayon mixture is pumped into a rotary mold machine that has thousands of crayon shaped holes, and chilled with cold water. An Instron testing device is used to check the barrel and tip strength of crayons because a strong crayon is a better crayon (sometimes kids grab crayons by the handful or press too hard when they draw or color).

    All Crayolas contain the same amount of paraffin wax blend. But their density depends on the amount of color pigments added. Therefore, some crayons will float in water while others will not, and some will sink faster than others. Find out for yourself by performing your own experiments (although we won¹t be responsible for actually telling you to dump your whole box of 96 colors into a bathtub?). No one is saying what pigments are really used because that information is top secret. Some examples for reds might be ocher (an iron oxide mineral), carmine (from an insect), or madder (from a plant). All we can be sure of is that several different pigments are used and that they are all non-toxic. If you are interested in recycling, can you think of a way to re-use your broken crayons instead of throwing them away? One thing to try, with the help of an adult, is to put all the broken pieces into an empty soup can and put this into a shallow pan of water on the stove. The adult can then heat the water enough to melt the crayons, and pour the warm wax into a new mold of some type.

    Fun Facts: The average American kid uses 730 crayons by the age of 10. Red and blue are the two favorite colors worldwide. Sulphur, a yellow-green combination, is the most disliked color in the world. The name Crayola ("oily chalk") is from the French word "craie", which means chalk, and "ola" (from oleaginous), which means oily. Although there are 96 different Crayola colors, there are only 18 different label colors. Among the 20 most recognized smells in the world, crayons placed 18th (first was coffee, followed by peanut butter). 

    --------------

    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    February 2000

    ----------------

    References: The Crayola Co.¹s website at www.crayola.com.