Encyclopædia Britannica
wax
any of a class of pliable substances of animal, plant,
mineral, or synthetic origin that differ from fats in being
less greasy, harder, and more brittle and in containing
principally compounds of high molecular weight (e.g., fatty
acids, alcohols, and saturated hydrocarbons). Waxes share
certain characteristic physical properties. Many of them
melt at moderate temperatures
(i.e., between about 35° and 100° C, or 95° and 212° F) and
form hard films that can be polished to a high gloss,
making them ideal for use in a wide array of polishes.
They do share some of the same properties as fats.
Waxes and fats, for example, are soluble in the same
solvents and both leave grease spots on paper.
Notwithstanding such physical similarities, animal and
plant waxes differ chemically from petroleum, or
hydrocarbon, waxes and synthetic waxes. They are esters
that result from a reaction between fatty acids and certain
alcohols other than glycerol, either of a group called
sterols (e.g., cholesterol) or an alcohol containing 12 or
a larger even number of carbon atoms in a straight chain
(e.g., cetyl alcohol). The fatty acids found in animal and
vegetable waxes are almost always saturated. They vary from
lauric to octatriacontanoic acid (C37H75COOH). Saturated
alcohols from C12 to C36 have been identified in various
waxes. Several dihydric (two hydroxyl groups) alcohols have
been separated, but they do not form a large proportion of
any wax. Also, several unidentified branched-chain fatty
acids and alcohols have been found in minor quantities.
Several cyclic sterols (e.g., cholesterol and analogues)
make up major portions of wool wax.
Only a few vegetable waxes are produced in commercial
quantities. Carnauba wax, which is very hard and is used in
some high-gloss polishes, is probably the most important of
these. It is obtained from the surface of the fronds of a
species of palm tree native to Brazil. A similar wax,
candelilla wax, is obtained commercially from the surface of
the candelilla plant, which grows wild in Texas and Mexico.
Sugarcane wax, which occurs on the surface of sugarcane
leaves and stalks, is obtainable from the sludges of cane-
juice processing. Its properties and uses are similar to
those of carnauba wax, but it is normally dark in colour and
contains more impurities. Other cuticle waxes occur in trace
quantities in such vegetable oils as linseed, soybean, corn
(maize), and sesame. They are undesirable because they may
precipitate when the oil stands at room temperature, but
they can be removed by cooling and filtering. Cuticle wax
accounts for the beautiful gloss of polished apples.
Beeswax, the most widely distributed and important animal
wax, is softer than the waxes mentioned and finds little use
in gloss polishes. It is used, however, for its gliding and
lubricating properties as well as in waterproofing
formulations. Wool wax, the main constituent of the fat that
covers the wool of sheep, is obtained as a by-product in
scouring raw wool. Its purified form, called lanolin, is
used as a pharmaceutical or cosmetic base because it is
easily assimilated by the human skin. Sperm oil and
spermaceti, both obtained from sperm whales, are liquid at
ordinary temperatures and are used mainly as lubricants.
About 90 percent of the wax used for commercial purposes is
recovered from petroleum by dewaxing lubricating-oil stocks.
Petroleum wax is generally classified into three principal
types: paraffin (see paraffin wax), microcrystalline, and
petrolatum. Paraffin is widely used in candles, crayons, and
industrial polishes. It is also employed for insulating
components of electrical equipment and for waterproofing
wood and certain other materials. Microcrystalline wax is
used chiefly for coating paper for packaging, and petrolatum
is employed in the manufacture of medicinal ointments and
cosmetics. Synthetic wax is derived from ethylene glycol, an
organic compound commercially produced from ethylene gas. It
is commonly blended with petroleum waxes to manufacture a
variety of products.
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