Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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wattle (bark)

A vegetable tanning material obtained from the bark of the black wattle (Acacia mollissima), indigenous to Australia but cultivated extensively in South Africa and other areas. Large quantities of wattle are exported, much of it to England, in the form either of the bark itself, or as the extract. The tannin content of the bark ranges from 30 to 45%, with the average being about 35 to 39%. Wattle is essentially a tannin of the condensed class; it has a high pH value, a low salts and acids content, and a relatively low viscosity, especially in warm solutions. It is very astringent, penetrates the hide substance rapidly, and has a high degree of tan fixation. Like most other vegetable tannins, it is seldom used alone, but generally in mixtures with myrabolans, sumac, valonea, etc. Also known as "mimosa." See also: VEGETABLE TANNINS . (175 )

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