The question arises to what extent the water balance of a hide is transferred to leather through the leathermaking process. The pivot is collagen: it has various degrees of water binding which differ in the physical properties of bound water molecules. Other proteinous hide components are destroyed and/or removed in beamhouse operations. The product of these operations is refined collagen. In tanning and wet finishing, the side-chain charges and microstructure of collagen are modified. In the resulting leather, the basic features of collagen remain unchanged and, with certain limitations, it reacts with water the same way as it does in hide.