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Tar can be produced from corn stalks by heating in a microwave. This process is known as pyrolysis.
Tar is a viscous black liquid derived from the destructive distillation of organic matter. Most tar is produced from coal as a byproduct of coke production, but it can also be produced from petroleum, peat or wood.

Types of tar

General

The word "tar" is used to describe several distinct substances. Naturally occurring "tar pits" (e.g. the La Brea Tar Pits in Los Angeles) actually contain asphalt, not tar, and are more accurately known as asphalt pits. Tar sand deposits contain various mixtures of sand (or rock) with bitumen or heavy crude oil rather than tar, as does the Tar Tunnel in Shropshire. "Rangoon tar", also known as "Burmese Oil" or "Burmese Naphtha", is actually petroleum. "Tar" and "pitch (resin)" are sometimes used interchangeably; however, pitch is considered more solid while tar is more liquid.

Coal tar

In English and French, "tar" is a substance primarily derived from coal. It was formerly one of the products of a gasworks. Tar made from coal or petroleum is considered toxic and carcinogenic because of its high benzene content, however, coal tar in low concentrations is used as a topical medicine. Coal and petroleum tar has a pungent odor.

Wood tar

In Northern Europe, the word "tar" refers primarily to a substance derived from wood, which is used even as an additive in the flavoring of candy and other foods. Wood tar is microbicidial and has a pleasant odor.

The heating (dry distilling) of pine wood causes tar and pitch to drip away from the wood and leave behind charcoal. Birchbark is used to make particularly fine tar (tökötti). The by-products of wood tar are turpentine and charcoal. When deciduous tree woods are subjected to destructive distillation the by-products are methanol (wood alcohol) and charcoal.

Uses

Tar is used in treatment of the skin-disease psoriasis, where coal tar is the most effective. Tar is also a general disinfectant. Petroleum tar was also used in ancient Egyptian mummification circa 1000 BC.[1]

Tar was a vital component of the first sealed, or "tarmac", roads. It was also used as seal for roofing shingles and to seal the hulls of ships and boats. For millennia wood tar was used to waterproof sails and boats, but today sails made from inherently waterproof synthetic substances have negated the need for tar. Wood tar is still used to seal traditional wooden boats and the roofs of historical shingle-roofed churches, as well painting exterior walls of log buildings.

In Finland wood tar was once considered a panacea reputed to heal "even those cut in twain through their midriff". A Finnish proverb states that if sauna, vodka and tar won't help, the disease is fatal. The use of wood tar in traditional Finnish medicine is because of its microbicidial properties.

Wood tar is also available diluted as tar water, which has numerous uses:
  • As a flavoring for candies (e.g. Terva Leijona) and alcohol (Terva Viina)
  • As a spice for food, like meat
  • As a scent for saunas. Tar water is mixed into water that is turned to steam to the air
  • As an anti-dandruff agent in shampoo
  • As a component of cosmetics
Mixing tar with linseed oil varnish produces tar paint. Tar paint has a translucent brownish hue, and can be used to saturate and tone wood and protect it from weather. Tar paint can also be toned with various pigments, producing translucent colours and preserving the wood texture. Because of its paint-like properties, wet tar should not be touched with bare skin, as it can dry to produce a stain, though paint thinner is effective in removing it.

Coal tar is listed at number 1999 in the United Nations list of dangerous goods.

See also

Sources

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Antipsoriatics (D05)
Topical: tarsTar
Topical: antracensDithranol
Topical: psoralensTrioxysalen - Methoxsalen
Topical: otherFumaric acid - Calcipotriol - Calcitriol - Tacalcitol - Tazarotene
Systemic: psoralensTrioxysalen - Methoxsalen - Bergapten
Systemic: retinoidsEtretinate - Acitretin
Viscosity is a measure of the resistance of a fluid to deform under either shear stress or extensional stress. It is commonly perceived as "thickness", or resistance to flow.
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Liquid is one of the four principal states of matter. A liquid is a fluid that can freely form a distinct surface at the boundaries of its bulk material.

Characteristics

A liquid's shape is determined by, not confined to, the container it fills.
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Destructive distillation is the process of pyrolysis conducted in a distillation apparatus to allow the volatile products to be collected. The process led to the discovery of many chemical compounds before such species could be prepared synthetically.
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Coal (IPA: /ˈkəʊl/) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation.
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Coke is a solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal.

The volatile constituents of the coal—including water, coal-gas, and coal-tar—are driven off by baking in an airless oven at temperatures as high
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Petroleum (Latin Petroleum derived from Greek πέτρα (Latin petra) - rock + έλαιον (Latin oleum) - oil) or crude oil
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Peat is an accumulation of partially decayed vegetation matter. Peat forms in wetlands or peatlands, variously called bogs, moors, muskegs, pocosins, mires, and peat swamp forests.
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The WOOD callsign may refer to:
  • WOOD-TV – an NBC-affiliated television station in Grand Rapids, Michigan
  • WOOD (AM) – an AM radio station in Grand Rapids, Michigan
  • WOOD-FM - an FM radio station in Grand Rapids, Michigan



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For other uses, see Tarpit (computing).


A tar pit, or more properly asphalt pit, is a geological occurrence where subterranean bitumen leaks to the surface, creating a large puddle, pit, or lake of asphalt.
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La Brea Tar Pits (or Rancho La Brea Tar Pits) are a famous cluster of tar pits located in Hancock Park in the urban heart of Los Angeles, California, USA. Asphalt (colloquially termed tar, which in spanish is termed brea
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City of Los Angeles

Flag
Seal
Nickname: The City of Angels, L.A.
Location within Los Angeles County in the state of California
Coordinates:
State
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The term asphalt is often used as an abbreviation for asphalt concrete. For the film, see Asphalt (film); for the novel, see Carl Hancock Rux.


Asphalt
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Tar sands is a common name of what are more properly called bituminous sands, but also commonly referred to as oil sands or (in Venezuela) extra-heavy oil. They are a mixture of sand or clay, water, and extremely heavy crude oil.
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Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, entirely soluble in carbon disulfide, and composed primarily of highly condensed polycyclic aromatic hydrocarbons.
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Heavy crude oil or Extra Heavy oil is any type of crude oil which does not flow easily. It is a relative term, compared to light crude oil, but relates to specific technical issues of its own on production, transportation, and refining.
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The Tar Tunnel is located on the north bank of the River Severn in Coalbrookdale near the village of Coalport, England, and now forms part of the Ironbridge Gorge Museum Trust.
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Shropshire
Motto: “Floreat Salopia” (“May Shropshire flourish”)

Geography
Status Ceremonial & (smaller) Non-metropolitan county
Origin Historic
Region West Midlands
Area
- Total
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Petroleum (Latin Petroleum derived from Greek πέτρα (Latin petra) - rock + έλαιον (Latin oleum) - oil) or crude oil
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Pitch is the name for any of a number of highly viscous liquids which appear solid. Pitch can be made from petroleum products or plants. Petroleum-derived pitch is also called bitumen. Pitch produced from plants is also known as resin.
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Gasworks or Gas house is a factory for the manufacture of gas. Coal gas (known in the USA as Town gas) was introduced to Great Britain in the 1790s as an Illuminating gas by the Scottish inventor William Murdoch.
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Toxicity is the degree to which something is able to produce illness or damage to an exposed organism. Toxicity can refer to the effect on a whole organism, such as a human or a bacterium or a plant, or to a substructure, such as a cell (cytotoxicity) or an organ (organotoxicity
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The of this article may be compromised by "weasel words".
You can help Wikipedia by removing weasel words.

The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation
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Benzene, or Benzol (see also Benzine) is an organic chemical compound with the formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and inflammable liquid with a sweet smell and a relatively high melting point.
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Coal tar is a brown or black liquid of high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal is carbonized to make coke or gasified to make coal gas.
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In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, penis, anus, throat, eye or the ear. Some hydrophobic chemicals such as steroid hormones can be absorbed into the body after being applied to the skin in the form
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Northern Europe is a term for the northern part of Europe, though its precise boundaries are vague and defined variously. It is a term that groups the Nordic countries (which are present in all definitions):

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Pyrolysis is the chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam.

It is used in chemical analysis to break down complex matter into simpler molecules for identification, for example by pyrolysis gas
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A microbicide is any compound or substance whose purpose is to reduce the infectivity of microbes, such as viruses or bacteria.

See also

  • Antibiotics
  • Bactericide
  • Fungicide
  • Microbicides for sexually transmittted diseases

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Dry distillation is the heating of solid materials to produce liquid or gaseous products (which may condense into solids). Dry distillation, however, is not a unit operation like distillation, but entails pyrolysis, i.e. decomposition of the solid.
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Pinus
L.

Subgenera
  • Subgenus Strobus
  • Subgenus Ducampopinus
  • Subgenus Pinus
See Pinus classification for complete taxonomy to species level.
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