Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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birch (bark)

The bark of the common European birch (Betula verrucosa) or (B. pubescens), used in leather manufacture, particularly in Russia, for hundreds of years. The outer bark, which peels off easily, is not used; it is the inner bark from which the tannin, in the amount of 10 to 15%, and 11% soluble non-tans, is extracted. Older trees, those 50 to 60 years of age, yield the richest tannin. Used alone, birch produces a pliable, leather of a yellowish-brown color; it is, however, more often mixed with some other tannin, often willow bark. In addition to tannin, the oil obtained from the bark is used to dress the leather, imparting to RUSSIA LEATHER its characteristic odor. Other species of birch have been used to a limited extent in North America and India. See also: VEGETABLE TANNINS . (175 )

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