Whatsapp:+8613794901196 This product is mainly used for the degree of discoloration of various papers, fabrics, leathers and other colored materials by external friction. This machine is used for the dry or wet white cotton cloth on the surface of the friction hammer (specified load). After rubbing the colored test piece at a certain speed and number of times, it is compared with the standard color chart to evaluate the decolorization level of the test piece visit http://www.professionaltestequipment.com