A lac washing machine is a specialized device used to clean raw lac, a resin secreted by lac insects, typically in the form of sticklac. The washing process usually takes 1 to 2 hours, during which the lac is soaked and mechanically agitated to remove impurities such as dirt, dust, and other unwanted materials. This ensures that the lac is clean and of higher quality, making it suitable for further processing, such as refining into shellac or for use in various industrial applications.