Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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putrefactive damage ( putrefaction )

A general source of hide and skin damage caused by bacterial action on the stock following flaying and before curing, or, at times, following soaking, but before tanning. A wet, unsalted skin at any point before tannage is in a very perishable state and is very susceptible to the invasion of putrefactive bacteria, especially on the flesh side of the skin. This is particularly the case under the climatic conditions generally prevailing in areas where skins are dried, rather than being cured by one of the salting processes. Often the bacteria will develop along the vascular system and leather produced from such stock is said to be VEINY LEATHER .

Putrefactive damage is often obvious before a skin is dried (but not necessarily during or subsequent to wet-salting, brining, etc.); however, subsequent to drying the damage is not readily perceptable and therefore may not be suspected. Once the affected skins reach the tannery, however, the damage is usually detected before they reach the limed condition. Once they are in soak they display a pitted condition, often honeycombed with small holes that may penetrate through the entire thickness of the skin. They may also be pitted and corroded, mainly on the flesh side.

This type of damage is not intensified by liming, but it is not unusual for both putrefactive and SUN DAMAGE to be present in the same skin, in which case even greater damage will be apparent after liming than before. Moreover, the presence of fatty tissue left after flaying may encourage putrefactive as well as sun damage.

The first indication of putrefaction (aside from odor) is hair slip, usually accompanied by a sensitive condition of the grain surface, so that the grain layer tends to rub away during normal processing of the stock. Slight rubbing gives a "dull grain," generally accompanied by blotchy finishing. Putrefaction also causes the general structure of the skin to become loose and flabby. (248 , 363 )

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