Crocking

Crocking is the transfer of color from dyed or printed fabric to another fabric or to skin or surfaces through rubbing or abrasion. It can occur with dry crocking, which happens without moisture, or wet crocking, which occurs when moisture is present during rubbing. Crocking is a standard measure of colorfastness in textiles and is separate from color change of the sample itself.

Causes include inadequate fixation of dye to the fiber, dye migration during finishing or washing, use of low-fast dyes, improper pretreatment, or finishing processes that leave loose color on the surface. The risk is higher on dark or bright shades, on fabrics with high surface roughness, or when softeners and resins reduce crocking resistance.

Testing and evaluation: Manufacturers use standardized crocking tests such as the crocking test with a mechanical crockmeter. A fabric sample rubs against a standard white test fabric under specified pressure and cycles in dry or wet conditions. After rubbing, both samples are rated against a gray scale for staining and color change, typically from 5 (no transfer) to 1 (heavy transfer). ISO and AATCC methods specify procedures.

Impact and mitigation: Crocking can affect consumer perception and product safety labeling. To reduce crocking, manufacturers select more colorfast dyes, optimize dye fixation, adjust polymer finishes, perform proper scouring and washing, and control moisture during processing. For apparel, laundering instructions and finish labeling reflect the crocking performance.