SATRA STD 422 Crockmeter
This test is designed for determining the degree of colour which may be transferred from the surface of coloured materials to other surfaces by rubbing. The machine takes its name from the term 'crocking' meaning the transfer of colouring matter or other substances from the test sample to a wet or dry cloth rubbed against it.
The STD422 consists of a base on to which a test sample is secured. A sliding mechanism is arranged to traverse a finger along the sample. The end of the finger is covered by a piece of cloth and a predetermined load is also applied to the finger during the sliding motion. Coloured leathers are usually tested using a white bleached cloth – for white leathers a black colour-fast cloth is employed.
The movement of the finger is obtained from a cranked drive by means of a handle. A test would normally consist of 10 turns of the handle at 1 turn/second. Assessment of colour transfer is made using the grey scale.
The white cloth, STD422CL/500, used for rubbing and the grey scales are available from SATRA Test Equipment.