Drying refers to the removal of water, or another solute "liquid", to reduce the content of residual liquid to an acceptably low value . The drying of materials is often the final operation in a manufacturing process, carried out immediately prior to packaging or dispatch. Drying is the operation often follows evaporation, filtration, or crystallization. In some cases, drying is an essential part of the manufacturing process, as for instance in paper making or in the seasoning of timber.