oil tanning
A "tannage" which involves the incorporation of
fish or marine mammal oils into inner splits or
frizzed-grain skins, usually wooled sheepskins.
The tanning agent is generally raw cod liver oil,
which, subsequent to being incorporated into the
skin, is induced to undergo oxidation and other
chemical changes while in contact with the fibers,
leading to a chemical combination of oil
derivatives with the fibers. The liberation of
heat accompanies and speeds up these chemical
reactions; however, there is the danger of the
oiled skins being heated to the point where they
may smoulder or even burn. Cod liver oil is not
readily taken up by the skins; therefore, for the
success of this process, it is essential to bring
the oil into the closest possible contact with the
fibers; this is accomplished by vigorous
mechanical action. Oil tanning is used principally
in the manufacture of chamois leather. At one time
it was referred to as "chamoising." (248 , 291 ,306 , 363 )
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