|Beeswax is really wax; not all things called wax (such as paraffin) actually are. (Ivan Alvarado/Reuters)|
The term wax covers a broad range of organic materials, all characterized by being malleable around room temperature, insoluble in water, and melting well below the boiling point of water.
Typically, they are esters — compounds of carbon, hydrogen, and oxygen — formed from an acid and an alcohol with a water molecule removed from the point at which they join.
Esters made from small molecules easily waft into the air and often have fruity or flowery smells that lead to their use in artificial flavorings and aromas. Esters made from larger molecules are too heavy to evaporate significantly and are therefore odorless. They are what we know as wax.
Many animals and plants make waxes. The most well-known is beeswax, which bees use to build hives. Bees make about a pound of wax for every 10 pounds of honey they produce.
Chemically, beeswax is largely myricyl palmitate — the ester of myricyl alcohol and palmitic acid, both long chainlike molecules that are large compared to the acids and alcohols that constitute the small esters with fruity smells.
Another well-known animal-generated wax is lanolin, produced by sheep to protect their wool and skin.
Plants make waxes to protect their leaves from dehydration, and the leaves on many plants look as glossy as waxed furniture. Carnauba wax, which comes from a Brazilian palm, is used for furniture polish.
When you rub an apple on your sleeve till it shines, you’re polishing it with a complicated mixture of waxes the tree makes to protect its fruits.
Petroleum and coal are derived from the dead bodies of plants and animals, so it should come as no surprise they contain waxes, but only rarely are these waxes extracted for commercial use. The most commonly known wax is Montan wax, derived from coal; it also contains fatty acids and alcohols.
What is usually sold as wax derived from petroleum isn’t really wax; it is mainly comprised of alkanes, short chains of carbon and hydrogen atoms with as many hydrogen atoms as possible and no oxygen atoms.
Paraffin is the most common product of this kind. It is referred to as wax because it has some similar physical properties, but is nothing at all like beeswax.
Ask Dr. Knowledge is written by Northeastern University physicist John Swain. E-mail questions to email@example.com or write to Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819.