Rotary Vertical Crockmeter Method
Rotary Rubbing Color Fastness Tester is used to determine the amount of color transferred from the surface of colored textile materials to other surfaces by rubbing. It is applicable to textiles made from all fibers in the form of yarn or fabric, whether dyed, printed or otherwise colored.There have two test methods as below:
Dry Crocking Test.
1 Tilt the upper half of the machine away to allow access to the base of the machine. Place a test square on the end of the vertical rod and fasten it with spring clip.
2 Hold the test specimen on the machine base at the point the vertical rod contacts the base. Tilt the upper half of the machine back to the operation position with the test square at the end of the shaft in contact with the test specimen. Place the weight supplied with the corckmeter on the vertical shaft to give the rubbing finger a downward force of 11.1N ±10% (40 oz ± 10%).
3 With the left hand, hold the test specimen in position on the base. Turn the crank 20 turns with the right hand. This produces about 40 reciprocal turns of the vertical shaft.
4 Tilt the upper part of the machine back and remove the test specimen ans the test square, condition and evaluate.
Wet Crocking Test.
1 Establish technique for preparing wet crock cloth squares by weighing a conditioned square, then thoroughly wet out while testing square in distilled water. Prepare only one square at a time.
2 Bring the wet pick-up to 65 ± 5% by squeezing the wet testing square between white AATCC blotting paper through a hand wringer or similar convenient means.
3 Avoid evaporative reduction of the moisture content below the specified level before the actual crock test is run.
4 Continue as directed in 1
5 Air dry the white test square, the condition before evaluating. In the case of napped, brushed or sanded material when loose fiber might interfere with the rating, remove the exteaneous fibrous material by pressing lightly on the crock circle with the sticky side of cellophane tape before evaluating.