Color Stability
Rubbing resistance measures the degree of color transfer from a printed or dyed fabric to an adjacent undyed cloth during dry or wet friction. The crock fastness of a fabric is evaluated using a standardized crockmeter that rubs a white cotton fabric across the sample under a set pressure. The resulting stain on the white fabric is evaluated against a greyscale.
This test determines if the dye is locked into the fibre.
Wet Dry
Dry friction always produces better results than wet friction because water lubricates the surface and releases unfixed dye molecules. When a fabric has poor wet crock fastness, the dye will transfer to skin or undergarments during wear. This is a common issue with indigo dyed denim where the dye is only held on the surface.
The mill must apply a washing step to remove loose surface color.
Improvement Process
Textile finishers use fixing agents to improve rubbing resistance. If the crock fastness is below the brand’s standard, the batch must be reprocessed. This reprocessing adds cost.
Inspection Protocol
Buying offices require laboratory reports for crock fastness before releasing the shipment from the factory. A score of four is usually required for dry testing, while a score of three is the minimum for wet testing. The test ensures that garments do not ruin other items in a household wash.
The results are recorded on the inspection certificate.
