Neutralising
From www.leather-dictionary.com - The Leather Dictionary
Acids which have penetrated into the leather during tanning, is removed again during the Neutralising stage. Alkaline sodium carbonate is used in a concentration of 1.2%. Neutralising is necessary, to allow fat-liquoring. No attempts to bring the pH value of leather to 7 are made during this stage, since this would dissolve the binding of the tannins to the skin-fibres and thus drastically reduce the durability of the leather. In practice, a pH value of 4-6 is desired.
Video about the leather production
The leather production in a modern tannery.
Process steps in the leather production |
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storage - soaking - liming - fleshing - splitting - pickling - tanning - neutralising - withering - sorting - shaving - dyeing (through colouring) and fatliquoring - drying - finish - softening - final check |
Tanning methods |
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Chrome tanning - Vegetable-tanned leather - Synthetic tanning - Tanning with fats and oils |