Textile testing instruments Crock-meter is used for determination of color fastness of dyed or printed textiles or leather is the crocking test. This test is used for the determination of color fastness against rubbing, either under dry or under wet conditions. In this test and moving brass finger of specified shape and size rubs against the test specimens and the amount of color transferred to a piece of abradant fabric fixed over the base of the moving finger are graded with the help of standard grey scales to evaluate the color fastness against rubbing.