1、Overview
It is more and more important to carry out tests according to different countries’ testing standards and conduct judgment on the results. Rubbing colorfastness in regards to exposure to friction intensity is one of the most important tests in textile quality inspection for colorfastness. The test results are directly related to the overall colorfastness of the fabric. Some dyes of poor quality can cause different degrees of harm to the human body.
Therefore, different organizations and countries have set standards to strictly limit the colorfastness of apparel and home textiles in order to minimize the potential dangers the products may cause. Different organizations and countries, according to their national custom and industrial development standards, have developed methods of testing the safety of the dye after being rubbed, similar to daily wear and tear. There are differences between these test methods and they have a certain impact on the test results.
What is crockmeter? Average friction is determined by conditions specified in the friction test machine, which is called Crockmeter. The crockmerter can be divided into motorized crockmeter and manual crockmeter. In crocking test, the standard white cloth (dry and wet) is fixed to the friction head, and under certain pressure, the dyed samples subsequently emitted certain chemicals. Friction from the standard white cloth was tested a specified number of times. First, the sample is dry, and the color transfer to the white cloth can be compared with the staining gray sample card, or color transfer sample card to assess the degree of loss in colorfastness, thus, the level of colorfastness is calculated.
2、Comparison of Rubbing Colorfastness Test Methods (Crockmeter Test Methods)
Test equipment used GB rubbing fastness tester, AATCC crockmeter and JIS crock meter type I. The friction head vertical pressure is 9N in crockmeter test. The warp or weft direction of the sample is consistent with the running direction of the rubbing head. The rubbing direction of the crockmeter test cloth is parallel to the length direction of the warp or rubbing cloth. Wet friction test uses the GB with grade 3 water, AATCC with ionized water, and the JIS with distilled water. The humidity control time is 4h. Table 1 shows the difference between the sample size, the standard rubbing cloth size, and the frictional stroke specified by the three test methods.
3、Test Comparison and Analysis
The 18 textiles tested the same sample according to different standard methods for colorfastness to rubbing test and yielded the following results:
3.1、Dry friction (dry rubbing) is better than wet friction.
3.2、Dry light-colored fabric exposed to wet friction holds better color fastness levels, generally 5/4 to 5; and dark fabrics, denim, corduroy and printed fabric hold poor color fastness levels, usually 2 ~ 3/2.
3.3、Dry and wet friction of flocking are basically the same. Different test methods do not affect the results.
3.4、Moist wool fabrics and pure polyester fabrics have better colorfastness than dry’s.
3.5、Under different friction methods, the fabric of the raw material composition also has a certain impact. There are differences between cotton fabrics, while pure polyester fabrics are basically the same.
3.6、Under different friction methods, the fabric structure makeup also has a certain impact. There are differences between plain weave fabrics, while twill weave fabrics are basically the same.
3.7、Under different friction test methods, velvet fabrics are basically the same.
3.8、For the same sample size, almost same friction test data was obtained. There will be a difference of 0.5 to 1.0, for the relative grades of the Japanese standard are slightly lower. However, the relative increase of the American standard produces higher grades and GB between the two.
4、Summary
Rubbing colorfastness tests are one of the basic items of textile color fastness tests, which has great significance for ecological textiles. Through the test of rubbing fastness, it is found that the type of test specimen, the type of standard friction white cloth, the moisture content of the white cloth and the test parameters such as temperature, humidity, vertical pressure, friction intensity, rubbing direction, Have a certain influence. Tests show that, for the same sample, different friction test data obtained sometimes has a difference of 0.5 to 1.0 level. Relatively speaking, the same sample, but the lowest level was measured by the Japanese standard, while the Chinese national standard compared to the Japanese standard and the American standard is not a suitable comparison.
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