The deliming operation in leather processing is a drum/paddle or pit based operation where two main objectives are met:
- Removal of alkali from the pelt and the consequent deswelling of the fibres.
- Lowering of the liquor pH to the values used in the bating process.
Deliming operations of cattle hides usually last 2 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.