Drenching was often difficult to control, as the enzymes did not restrict their attack to the carbohydrates either in the solution or the skins, but often degraded the fibers of the dermal network as well. In addition, too much acid swelling was produced with resulting impairment of the skin structure and, therefore, of the quality of the leather produced.
When drenching is used today, as in certain vegetable tannages calling for specific acid conditioning during the early stages of tanning, weak solutions of organic acids, such as lactic, acetic and formic, are used in lieu of fermented cereal solutions.
Because of the gas bubbles of carbon dioxide produced by fermentation, which caused the skins to rise to the surface of the paddle, the process was also called "raising." (291 , 363 )
Timestamp: Saturday, 19-Nov-2011 13:18:40 PST
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