Delime and bating - Toxic gases (deliming)

Removal of calcium from the hide substances after liming is essential, if the later pickling and tanning processes are to proceed. This is not as straightforward as it seems, in view of the difficulty of obtaining uniform results throughout the hides, and due to the potential water and air pollutants released. TFL is aware, and ready to advise!

WARNING - Delime, bating and pickling processes can release toxic gases - Ammonia or hydrogen sulphides and the appropriate respiratory protective equipment must be worn.

Deliming or more correctly the neutralisation and removal of both bound and unbound lime from the pelts to prepare for the bating and subsequent processes. Problems arise when the process takes too long to reach the required state of neutralisation as classically tested by Phenolphthalein. The delime process and the waste waters so produced can be polluting when using ammonia salts due to atmospheric odours (ammonia) and high nitrogen levels in the waste water.


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