Testing for color fastness to crocking requires the use of a crock tester, usually a rubbing head (such as a rubbing finger or rubbing cloth) and a corresponding rubbing rod or arm. The following are the general testing steps:
1. Prepare the sample: The prepared sample needs to be cut to the appropriate size for testing as required. For textiles, typically a sample size of 2.5 cm x 5 cm is used and pre-treated (such as washing and drying).
2. Mount the sample: Clamp the sample on the friction tester, making sure it is firmly fixed. The rubbing head should be tightly attached to the surface of the sample to be tested.
3. Set test parameters: Set the parameters of the friction tester, such as friction force, friction speed, and reciprocating friction times, according to standards or requirements. These parameters will vary according to different applications and standards.
4. Perform the test: start the friction testing machine, and make the friction head reciprocate on the surface of the sample. An inspection is usually done after each back and forth rub to observe pigment transfer or color change.
5. Evaluate the test results: After the test is completed, compare the sample to the standard to evaluate the color change and pigment transfer. This can be done using gray scale or a scoring system. According to the degree of color change, the result is given the corresponding grade of color fastness to rubbing.
It is important to note that different industries and applications may have their own specific requirements and assessment methodologies. Crockfastness testing can also be tailored and modified on a case-by-case basis to suit the needs of a particular material or product.
Through the color fastness to rubbing test, the abrasion resistance and color stability of the material in use can be evaluated. This is important for color stability applications such as textiles, leather, coatings and printing. Test results can help guide material selection, product improvement, and quality control to ensure that the product will reduce color change and fading in actual use.