Wax refer to a class of
chemical compounds that are
plastic (
malleable) near ambient temperatures. Characteristically, they
melt above 45 °C (113 °F) to give a low
viscosity liquid. Waxes are
insoluble in water but soluble in petroleum based solvent. All waxes are
organic compounds, both synthetic and naturally occurring.
:
foundation, made by pressing beeswax between patterned metal rollers.]]
Types
Waxes are organic compounds that characteristically consist of a long
alkyl chains. Natural waxes are typically
esters of
fatty acids and
long chain alcohols. Synthetic waxes are long-chain hydrocarbons lacking
functional groups.
Plant and animal waxes
Waxes are
biosynthesized by many plants or animals. They typically consist of several components, including wax esters, wax acids, wax alcohols, and hydrocarbons. Wax esters are typically derived from a variety of
carboxylic acids and a variety of
fatty alcohols. The composition depends not only on species, but also on geographic location of the organism. Because they are mixtures, naturally waxes are softer and melt at lower temperatures than the pure components.
Animal waxes
The best known animal wax is
beeswax, but other insects secrete waxes. A major component of beeswax is the
ester myricyl palmitate substance which is used in constructing their
honeycombs. Its melting point is 62-65 °C.
Spermaceti occurs in large amounts in the head oil of the
sperm whale. One of its main constituents is
cetyl palmitate, another ester of a
fatty acid and a
fatty alcohol.
Lanolin is a wax obtained from wool, consisting of esters of
sterols.
Plant waxes
Especially in warm climates, plants secrete waxes as a way to control evaporation and hydration.
Petroleum derived waxes
Although most natural waxes are esters, paraffin waxes are
hydrocarbons, mixtures of
alkanes usually in a
homologous series of chain lengths. These materials represent a significant fraction of petroleum. They are refined by vacuum distillation. Paraffin waxes are mixtures of saturated of n- and isoalkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds. The degree of branching has an important influence on the properties. Millions of tons of paraffin waxes are produced annually. They are used in adhesives, in foods (such as chewing gum and cheese wrapping), in cosmetics, and as coatings.
Montan wax
Montan wax is a fossilized wax extracted from coal and
lignite. It is very hard, reflecting the high concentration of saturated
fatty acids and alcohols, not esters that characterize softer waxes. Although dark brown and smelly, they can be purified and bleached to give commercially useful products.
Polyethylene and related derivatives
Some waxes are obtained by cracking polyethylene at 400 °C. The products have the formula (CH
2)
nH
2, where n ranges between about 50 and 100. As of 1995, about 200 million kilograms/y were consumed. The main use of polyethylene and polypropylene waxes is in the formulation of colourants for plastics. Waxes confer matting effects and wear resistance to paints. Polyethyelene waxes are incorporated into inks in the form of dispersions to decrease friction. They are employed as
release agents. They are also used as slip agents, e.g. in furniture, and corrosion resistance.
Candles
Waxes and hard fats such as
tallow have long been use to make
candles, used for lighting and decoration in a number of religious traditions, including Christianity and Hinduism, as well as various neo-pagan religions such as Wicca. The Emperor Constantine is reported to have called for the use of candles during an Easter service in the 4th century AD. Candles continue to be used today by Christians in worship as symbols of the light of Christ. In the Roman Catholic Church, beeswax candles are used, since a colony of bees is a celibate sisterhood with a single mother. Candles of wax or tallow took the place of lamps used in various Jewish rituals such as the Sabbath lights; in the Havdalah ceremony; and the Hanukkah lights. A synagogue had to be well lit, and pious folk used to donate candles for the purpose. On the basis of the verse: 'The soul of man is a candle of the Lord', a special candle which burns twenty-four hours is kindled on the anniversary of the death of a near relative (Yahrzeit) and often two lighted candles are placed at the head of the corpse awaiting burial.. Candles have also played a role in
pagan religions and in modern humanist festivals. Virtually all rituals in
Wicca include the lighting of altar candles, where two main candles are often used to represent the God and the Goddess; and the lighting of candles is a central theme at the Wiccan holiday of Brigid or Imbolc, which is also known as Candlemas or the Feast of the Waxing Light. Wax candles were also used in
secular life for lighting, signals in warfare, safety in travel and for time keeping, and are still in popular use today to provide soft lighting for meals and other social activities.
Other uses
Waxes are used to make
wax paper, impregnating and
coating paper and card to waterproof it or make it resistant to staining, or to modify its surface properties. Waxes are also used in
shoe polishes,
wood polishes, and automotive polishes, as
mold release agents in
mold making, as a coating for many
cheeses, and to
waterproof leather and fabric. Wax has been used since antiquity as a temporary, removable model in
lost-wax casting of
gold,
silver and other materials.
Wax with colorful pigments added has been used as a medium in encaustic painting, and is used today in the manufacture of crayons and colored pencils. Carbon paper, used for making duplicate typewritten documents was coated with carbon black suspended in wax, typically montan wax, but has largely been superseded by photocopiers and computer printers. In another context, lipstick and mascara are blends of various fats and waxes colored with pigments, and both beeswax and lanolin are used in other cosmetics. Ski wax is used in skiing and snowboarding. Also, the sports of surfing and skateboarding often use wax to enhance the performance. Beeswax or coloured synthetic wax is used to decorate Easter eggs in Ukraine and the Czech Republic. Paraffin wax is used in making chocolate covered bon-bons. Wax is also used in wax bullets, which are used as simulation aids.
Wax types
Animal waxes
Beeswax - produced by honey bees
Chinese wax - produced by the scale insect Ceroplastes ceriferus
Earwax - found in the human ear.
Lanolin (wool wax) - from the sebaceous glands of sheep
Shellac wax - from the lac insect Kerria lacca
Spermaceti - from the head cavities and blubber of the sperm whale
=== Vegetable waxes ===
Bayberry wax - from the surface wax of the fruits of the bayberry shrub, Myrica faya
Candelilla wax - from the Mexican shrubs Euphorbia cerifera and Euphorbia antisyphilitica
Carnauba wax - from the leaves of the Carnauba palm, Copernica cerifera
Castor wax - catalytically hydrogenated castor oil
Esparto wax - a byproduct of making paper from esparto grass, (Macrochloa tenacissima)
Japan wax - a vegetable triglyceride (not a true wax), from the berries of Rhus and Toxicodendron species
Jojoba oil - a replacement for spermaceti, jojoba is pressed from the seeds of the jojoba bush, Simmondsia chinensis
Ouricury wax - from the Brazilian feather palm, Syagrus coronata.
Rice bran wax - obtained from rice bran (Oryza sativa)
Soy wax - from soybean oil
Mineral waxes
Ceresin waxes
Montan wax - extracted from lignite and brown coal
Ozocerite - found in lignite beds
Peat waxes
Petroleum waxes
Paraffin wax - made of long-chain alkane hydrocarbons
Microcrystalline wax - with very fine crystalline structure
Petroleum jelly
Synthetic waxes
Polyethylene waxes - based on polyethylene
Fischer-Tropsch waxes
Chemically modified waxes - usually esterified or saponified
substituted amide waxes
polymerized α-olefins
See also
Slip melting point
References
External links
Waxes
www.microcrystallinewax.net, resource for microcrystalline wax research
Waxes
