Oak bark

Oak bark

Oak bark

Specification & Spread

Oak bark — cortex quercus
Common oak (English oak) — quercus robur l. ( = quercus pedunculata ehrh.)
Durmast oak — quercus petraea liebl. ( = quercus sessiliflora salisb.)
Beech family — fagaceae

Common oak

Common oak is a tree up to 40 m tall, with a wide spreading head and a stock up to 7 m in diameter. The young shoots are olive-brown, then silver-grey, somewhat shiny – «smooth». The bark of old branches are dark grey and deeply fissured.
The leaves are attached by short (up to 1 cm) petioles, obovate in outline, pinnatilobate with 5-7 (9) pairs of laminas, with deciduous stipules, leathery. It is shiny above and lighter below. The flowering of oak begins at the age of 50. It blooms simultaneously with the blooming of leaves.
The flowers are dioecious: the male flowers are  in drooping earrings, the female ones are sessile, 1-2 each.
The fruit is an acorn, naked, brownish brown with a cup-shaped or saucer-shaped ply, with a long stem.
The trees growing alone, bear fruit every year, in the forest – after 4-8 years.

It blooms in April – May, the fruits ripen in September – October.

Durmast oak

Durmast oak differs from common oak primarily by its longer petiole (petiole length is 1-2.5 cm).

Spreading. Oak is the main forest-forming species of deciduous forests in the European part of the country. In the north comes to St. Petersburg and Vologda, the eastern border of spread – the Urals. It also grows in the Crimea and the Caucasus. Durmast oak grows on the slopes of the mountains of the North Caucasus, in the Crimea and some parts of Ukraine.

Habitat. It grows in the part of deciduous and coniferous deciduous forests. It grows in the floodplains of the river forms pure oak forests (oak forests).


Oak bark contains:

  • 8-12% of tannins;
  • phenols – resorcinol, pyrogallol;
  • gallic acid;
  • catechins, dimeric and trimeric compounds of catechins;
  • flavonoids – quercetin, leukoanthocyanidins;
  • triterpene dammaran compounds.

Harvesting and storage of raw materials

Harvesting. The «smooth» bark is harvested in early spring during the sap flow, when it is easily separated from the wood, on the ground logging and cutting areas from the branches and young stalks before the leafing. Old tree stacks are usually covered with a thick cork layer with cracks. The bark of such trees is unsuitable for harvesting. In the young bark is much more tannins. To remove the bark, make circular cuts with a knife at a distance of 30-35 cm from one another, and then connect them with two longitudinal cuts and remove the bark.

Security measures. Harvesting is carried out with the permission of forestry in specially designated areas. Oak grows slowly.

Drying. It is dried n the shade, under a shed or in a well-ventilated area, spread out in a thin layer on the fabric and stirred daily. Care must be taken to prevent rainwater from getting into the raw materials, since the soaked bark loses a significant amount of tannins. It can be dried in the sun. The yield of dry raw material is 45-50% of freshly harvested material.

Storage. It is stored in dry and well-ventilated areas.

External signs of raw materials

Whole raw material

The pieces of bark are tubular, grooved or in the form of narrow strips of various lengths with a thickness of about 2-3 mm (up to 6 mm).
The outer surface is shiny, less often matte, smooth or slightly wrinkled, sometimes with small cracks. Transversely elongated lentils are often visible.
The inner surface is with numerous longitudinal thin prominent ribs.
At the break, the outer crust is granular, even, the inner one is strongly fibrous and spongy.
The colour of the bark is light brown or light grey, silver and yellowish-brown inside.
The smell is weak, peculiar, aggravated by wetting of the bark with water. The taste is very astringent.

Milled raw material

The pieces of bark of various shapes are passing through a sieve with 7 mm diameter holes.
The colour is light brown, light grey, silver or yellowish-brown.
The smell is weak, peculiar and aggravated by wetting of the bark with water. The taste is very astringent.


The powder is yellowish-brown particles passing through a sieve with openings 0.5 mm in size. The smell is weak and peculiar. The taste is very astringent.


Ash tree bark (European ash – Fraxinus excelsior L., olive family – Oleaceae) is dull, grey, easily distinguished by morphological and anatomical features. Under the microscope, an intermittent mechanical belt with a small number of stony cells is visible. The fiber is without crystal lining.

Properties and application

The oak bark decoction has astringent, denaturing proteins properties that provide anti-inflammatory effect.
Antimicrobial and antiprotozoal effects are associated with both derivatives of gallic acid, and the presence of catechins.

Application of oak bark

Broth oak bark (1:10) apply:

  • in acute and chronic inflammatory diseases of the oral cavity in the form of gargles,
  • applications to the gums for stomatitis, gingivitis, etc.

As an antidote for poisoning with heavy metal salts, alkaloids, mushrooms, bleached, dope, food poisoning and other poisonings, 20% decoction of oak bark is used to wash the stomach. In case of burns and frostbite, 20% decoction of oak bark is also used in the form of applications of napkins moistened with cold decoction to the affected places on the first day. Less commonly, oak bark (in collections) is used internally for gastroenterocolitis, dysentery, small gastrointestinal bleeding.


  • kidney, gallbladder, or liver problems;
  • undergoing acute gastritis, ulcers or cholecystitis;
  • having problems with defecation (constipation);
  • pregnant and lactating women;
  • children under 3 years old.