The bark of the chestnut is not used because it imparts a dark color to the tannin, and its high sugar content would result in a higher percentage of soluble non-tans in the extract. The usual tannin content of the southern European chestnut is 10 to 13%, or higher, which is considerably higher than that obtained from trees in northern climates. The wood does not seem to reach its highest tannin content until the trees are at least 30 years old.
Chestnut extract tans rapidly and produces a firm leather. If used alone, however, it may impart a reddish color to the leather that is not desirable; therefore, it is used in combination with quebracho, mimosa, myrabolans, and valonia.
Chestnut is one of the pyrogallol class of tannins, and has a naturally low pH value. It also has a relatively low salts content and a high acids content. See also: VEGETABLE TANNINS . (175 , 306 , 363 )
Timestamp: Saturday, 19-Nov-2011 13:18:40 PST
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