Beeswax is a natural animal wax secreted by bees and used to create the honeycombs of the hive. The natural color of beeswax when it is secreted is white. (See beeswax unrefined.)
Beeswax is the classic component of encaustic paint and all other wax related arts from ancient times. Its great versatility as an art material derives from its stability as a solid at normal temperatures and its fluidity at relatively low heated temperatures, its resistance to moisture, its ability to be polished, the range of possible surface textures, its adhesiveness, its ability to transparentize, and its plastic structural properties that allow it to be cast, carved, molded, roughened, incised, and scraped.
Most of the harvested beeswax is colored in a range of earthy hues from yellow to black. The coloration is caused by pollen and propolis (see definition). The higher up in the hive the wax is, the less it will be colored. The caps that cover the cells of the hive are usually white. Other impurities include dirt and body parts from the bees.
Propolis is a resinous substance collected from plants by the bees and secreted from the thorax of the bee when constructing the hive. Its purpose is to cement together the wax of the hive. For this reason, it is known as “bee glue.”
Beeswax varies in its ability to be refined depending on strain of bees, the vegetation from which the bee derived its pollen, weather-related stress on the bee (which affects the amount of propolis in the wax), the age of the wax in the hive, etc. These conditions make some waxes unable to be refined (or bleached) to a white color. These are sold as refined yellow waxes.
The industrial bleaching of beeswax is done in one of three ways:
- chemical bleaching, using peroxide or sulfuric acid: Chemical bleaching can be harsh on the wax, creating free fatty acids and making the wax more reactive to pigments and pollutants. Chemical bleaching can whiten colorants that other bleaching processes can’t, but these colorants can later return to their original color.
- sun bleaching, in which the wax is exposed to the sun, which bleaches out the colorants: Sun bleaching is a gentle and effective method of bleaching. Sun-bleached wax is usually softer. But the process is expensive and requires a great deal of space.
- Filtration, in which the wax is forced through a series of paper filters containing activated carbon. Filter bleaching is accomplished by filtering the wax through a mixture of activated carbon and clay that absorb the colorants. The wax is then run under pressure through a series of paper filters that take out all foreign matter.
Of these three, filtration is preferrable.
Pharmaceutical grade beeswax
Pharmeceutical grade beeswax is a standard set by the government that certifies that the wax meets certain chemical requirements and that it is pure beeswax, unadulterated with other waxes (such as paraffin or microcrystalline), rosins, etc. The chemical standards are mainly of importance to the cosmetic and pharmaceutical use of beeswax. For the artist, the main importance is the physical standard that the wax is unadulterated.
Wax is a plastic material that comes from many sources:
- Animal: beeswax
- Vegetable: carnauba, candelilla
- Petroleum: paraffin, microcrystalline
- Mineral: montan, ozokerite
Chemically animal and vegetable waxes have similar properties to animal and vegetable oils. The waxes differ from the oil mainly in their physical characteristics in that they are solid at normal temperatures while the oils are fluid. As a result, they do not have a drying time but change from fluid to solid in very short time to temperature.
Unlike animal and vegetable waxes, petroleum waxes are chemically inert and less reactive. Their drawbacks are that they will oxidize and yellow over time if exposed to the air. Paraffin is a very brittle wax that makes it problematic when used for encaustic.