Drying Requirements in Lac Processing and Scope of Improvement

Lac is a natural resin having wide applications ranging from surface coating to synthesis of fine chemicals. The basic raw material for lac industry is stick lac, which is used for making seed lac, shellac, bleached lac and other value added products. Drying is an important unit operation in preparation of these semi-refined and finished products. The most important parameter in drying of lac is drying temperature, which should be kept below its softening temperature (40–50°C) during drying operation. The various lac processing units fall into two categories, namely non-mechanized and mechanized units. In non-mechanized unitsdrying is carried out either in mild sun-light or in shade manually employing labour; whereas in mechanized units, the drying operation is mechanized to some extent for seed lac, but for products like bleached lac and other value added products, proper drying is still a tough task. The paper discusses the drying requirements for different lac products like stick lac, seed lac, bleached lac, aleuritic acid, lac dye and extent of mechanization of this operation and scope of improvement in it.