One of the test for determination of colour fastness of dyed or printed textiles or leather is the crocking test. This test is used for the determination of colour 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 under test and the amount of colour 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 colour fastness against rubbing.

Crockmeter consists of a rigid flat metalic platform on which the test specimen can be held firmly and a abrading finger which rubs against it under a specified load. The platform is fixed over the base of the equipment and lies in a horizontal plane. The test specimen is held firmly over an abrasive paper which is pasted on the upper face of the platform, with the help of two pins holding it at both ends.
The abrading finger has a flat circular rubbing face which is covered with 4 piece of white abradant fabric during the test. The abradant fabrics picks up colour lost by the test specimen during rubbing. It is held over the finger with the help of a tapered ring. Motion to the finger is given through a reciprocating arm with runs an two ball bearings to minimize friction and to apply a uniform load on the finger. The arm is moved by a manually operated crank and connecting link.
The equipment is finished in dark metallic paint and bright chrome plating to give it a corrosion resistant finish.
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