Birch tar or birch pitch is a substance (liquid when heated) derived from the

dry distillation Dry distillation is the heating of solid materials to produce gaseous products (which may condense into liquids or solids). The method may involve pyrolysis or thermolysis, or it may not (for instance, a simple mixture of ice and glass could be ...

of the bark of the

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...

tree.

Compounds

It is composed of

phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ar ...

such as

guaiacol Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing an methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs w ...

cresol Cresols (also hydroxytoluene or cresylic acid) are a group of aromatic organic compounds. They are widely-occurring phenols (sometimes called ''phenolics'') which may be either natural or manufactured. They are also categorized as methyl phen ...

, xylenol, and creosol.

Ancient and modern uses

Birch tar was used widely as an

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

as early as the Middle

Paleolithic The Paleolithic or Palaeolithic (), also called the Old Stone Age (from Greek: παλαιός ''palaios'', "old" and λίθος ''lithos'', "stone"), is a period in human prehistory that is distinguished by the original development of stone to ...

to early

Mesolithic The Mesolithic (Greek: μέσος, ''mesos'' 'middle' + λίθος, ''lithos'' 'stone') or Middle Stone Age is the Old World archaeological period between the Upper Paleolithic and the Neolithic. The term Epipaleolithic is often used synonymousl ...

era.

Neanderthals Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While ...

produced tar through the dry distillation of

birch bark Birch bark or birchbark is the bark of several Eurasian and North American birch trees of the genus ''Betula''. The strong and water-resistant cardboard-like bark can be easily cut, bent, and sewn, which has made it a valuable building, crafti ...

as early as 200,000 years ago. A study from 2019 showed that birch tar production can be a very simple process, merely involving the burning of birch bark near smooth vertical surfaces in open air conditions. A rare find from the Dutch North Sea shows that Neanderthals used birch bark tar as a backing on small 'domestic' stone tools. Birch tar also has been used as a

disinfectant A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than st ...

, in

leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs ...

dressing, and in medicine. 5,000-year-old

chewing gum Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/ plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. Its ...

made from birch bark tar and still bearing tooth imprints, has been found in Kierikki in Finland. Genetic material retained in the gum has enabled novel research regarding population movements, the types of foods consumed, and the types of bacteria found on their teeth. A different chewing gum sample, dated to 5,700 years old, was found in southern

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...

. A complete

human genome The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...

and oral

microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...

was sequenced from the chewed birch pitch. Researchers identified that the individual who chewed the pitch was a female closely related genetically to

hunter-gatherers A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi ...

from mainland Europe. Ends of

fletching Fletching is the fin-shaped aerodynamic stabilization device attached on arrows, bolts, darts, or javelins, and are typically made from light semi-flexible materials such as feathers or bark. Each piece of such fin is a fletch, also known as a ...

arrow An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers ca ...

s were fastened with birch-tar and birch-tar-and- rawhide lashings were used to fix the blade of axes in the Mesolithic period.

Russia leather Russia leather is a particular form of bark-tanned cow leather. It is distinguished from other types of leather by a processing step that takes place after tanning, where birch oil is worked into the rear face of the leather. This produces a leather ...

is a water-resistant leather, oiled with birch oil after tanning. This leather was a major export good from seventeenth and eighteenth century Russia, as the availability of birch oil limited its geographical production. The oil impregnation also deterred insect attack and gave a distinctive and pleasant aroma that was seen as a mark of quality in leather. Birch tar is also one of the components of Vishnevsky liniment. Birch tar

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

is an effective repellent of

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

s. The repellent effect lasts about two weeks. The repellent effect of birch tar oil mixed with

petroleum jelly Petroleum jelly, petrolatum, white petrolatum, soft paraffin, or multi-hydrocarbon, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons (with carbon numbers mainly higher than 25), originally promoted as a topical ointment for its ...

applied to a fence lasts up to several months. Birch tar oil has strong antiseptic properties Wanamaker, L
"Birch Tar Oil A Powerful Antiseptic"
''OtzisPouch'', 2020-04-01 owing to a large amount of phenol derivatives and terpenoid derivatives. Birch tar oil was used in the 18th Century alongside

civet A civet () is a small, lean, mostly nocturnal mammal native to tropical Asia and Africa, especially the tropical forests. The term civet applies to over a dozen different species, mostly from the family Viverridae. Most of the species diversity ...

and castoreum and many other aromatic substances to scent the fine Spanish leather Peau d'Espagne. At the turn of the 20th Century, birch tar has become a specialty fragrance material in

perfumery Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. T ...

as a base note to impart a leathery, smoky note in fragrances, especially from the leather and tobacco genre, and to a lesser extent in Chypres, especially Cuir de Russie perfumes and fragrance bases, typically together with castoreum and isobutyl quinoline. It is used as an ingredient in some soaps, i.e. the scent of Imperial Leather soap, though other tars (i.e. from pine, coal) with an equally phenolic and smoky odour are more commonly used in soaps as a medicating agent.

References

External links

Non-video demonstrationTreating Leather With Birch Tar
Adhesives Non-timber forest products {{material-stub