Birch bark oil

Description

The living inner layers of the papery bark of some Birch trees produce a dark brown sap or oil that is rich in tannins. The birch trees most commonly used are the European birch (Betula verrucosa) and the common birch (Betula pubescens). The bark contain 10-15% water soluble tannins and about 11% non-soluble oils. Russian leather was tanned with the extract to produce a pliable yellowish brown leather then rubbed with the oil on the flesh side. This gave the leather a characteristic woody smell. Birch bark extract is often mixed with Willow bark extract for tanning. The dark brown sap was also used as an ancient adhesive.

Synonyms and Related Terms

aceite de corteza de abedul (Esp.); birchbark oil; birch oil

Authority

• Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986

• Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982

• John S. Mills, Raymond White, The Organic Chemistry of Museum Objects, Butterworth Heineman, London, 2nd ed., 1994