Principle of color fastness to crocking

According to the crockmeter test method, strapping dry or wet cotton cloth on the surface of the friction head of the machine with a metal buckle, make the sample rub with the white crockmeter test cloth for friction, contrast the gray card, compare the color degree of the white cotton cloth for friction with the gray-colored grade gray sample card, judgement the grade of colorfastness to crocking.

Significance of crocking test

Fabric friction can exist in our real life in various ways, such as the friction between fabric and lining when people wear clothing, friction in various splicing parts, friction when sitting on objects, and so on. These conditions are likely to affect the appearance of the garment and even endanger our health because of the poor rubbing fastness of the fabric, resulting in color transfer. The fastness to rubbing is closely related to our life and should be paid enough attention to.

What is a crocking meter?

The product crockmeter is a kind of test instrument that uses the test simulation environment to test the solid degree of the sample color. From the beginning of the manual friction tester to the present motorized crockmeter, from the testing of textiles to the testing of leather, colour fastness to rubbing test method become more and more(for more information on crockmeter testing, please refer to the crockmeter Wikipedia).

Comparison of crockmeter

At present, different countries adopt different crocking test standards. For example, the moisture content of wet friction in AATCC8 test method should be 65%, while the other standards are 95%~100%, and so on. The specific parameters of the different criteria are shown in the following table:

 

Table   Sample Specifications

Item	GB/T 3920.5-1997	AATCC 8-2004	JIS L 0849-1996
Sample Size/mm	200×5	130×50	Rub Test Machine I 140×50
Friction Cloth Size/mm	Fleece：50×50 Non-Cashmere：25×100	50×50	50×50
Friction Head Size	（Round）Non-Cashmere：∮16mm (Square)Cashmere：19×25mm	(Round): ∮16mm	(Round) Non-Cashmere：∮16mm Tester I: Friction head quality of about 900g Tester II：Friction head quality of about 200g
Frictional movement/mm	100	104±3	100
Degree of friction	Reciprocating friction 10 Times every 10 Seconds	Reciprocating friction 10 Times every 10 Seconds	Test machine I: reciprocating friction within 10s 10 times Tester II: 100 reciprocating friction within 200s
Wet friction cloth moisture content/%	100±5	65±5	100
Comments on test results for staining gray card	GB gray staining sample card	AATCC gray scale rating, stained gray card	JIS contaminated with gray grading card

According to the actual demand of production development and the difference between rubbing and crocking, At present, there are the following types of rub test machine: crock meter, which meets the crockmeter ASTM, product AATCC crockmeter, which conforms to the common standard, rubbing fastness tester, which conforms to the JIS standard, and IULTCS rubbing fastness tester, which can test the colour fastness to friction of leather.