[citation needed] The interfibrillary proteins are denatured by the presence of alkali (particularly sodium sulfide), rendered soluble, facilitating their removal from the leather.
Removal is done by the mechanical action of liming or reliming, but more prominently when the pelt is deswelled (during deliming).
Failure to remove these proteins results in a hard, tinny leather (due to fibre glueing upon drying) that is brittle and inflexible.
Keratin that is present in the hair, scales and in the epidermis of the skin is hydrolyzed in the presence of alkali (at pH values greater than 11.5).
However, this weight also needs to take into consideration that proteins (especially the hair) have been removed, and the fleshing operation is often performed after liming.