The deliming operation in leather processing is a drum/paddle or pit based operation where two main objectives are met:[1] Deliming operations of cattle hides usually last two hours and are generally associated with the alkaline phase of beamhouse operations.
The progress of deliming in pelts is monitored by the checking of pH values of process liquors and in the cutting of a pelt cross-section.
Phenolphthalein is used to monitor deliming pelt cross-sectional progress.
The deliming process can be done with acids that can be rapid in their pH adjustment.
Ammonium sulfate and ammonium chloride can be used as deliming agents and they follow the following chemistry: The ammonium ion is then free to penetrate the pelt cross-section and further ionise to act as an acid: The protons can then serve two functions, namely to protonate basic groups of the collagen and neutralize solution alkali chemicals.