Waxes are thermoplastic materials (i.e., they soften when heated, and return to their original condition when cooled), but because they are not high polymers (i.e., macromolecules consisting of a large number of monomers), they are not considered to be plastics. Most waxes are water repellent, have smooth textures, low toxicities, and are free of objectionable odors.

Many waxes consist of simple esters, and therefore can be thought of as containing an acid part and an alcohol part. The acid portions of the molecules are made up of a mixture of fatty acids, and the alcohol portions are simple long-chain alcohols. These waxes tend to be solid because they have relatively high molecular weights.

Ester waxes usually have higher melting points than fats (60 to 100° C), and they tend to be harder. In animals and plants, they provide protective coatings. The leaves of plants are coated with...