Crocking is the term for dye transferring off the surface of a fabric through friction alone, without any water or washing involved. On jeans, this shows up as blue staining on skin, light coloured furniture, car seats or other clothing after contact with new or dark denim, caused by loose indigo particles sitting on the surface of the yarn rather than dry, deep washing removing them.
Crocking is most noticeable on very dark, raw or unwashed denim, since these have had the least handling to remove loose surface dye, and it typically reduces significantly after the first few washes as the excess indigo is rinsed away. Darker, deeply dyed jeans are more prone to crocking than lighter or pre washed pairs, and humid or damp conditions can make it worse, since moisture helps dye particles transfer more easily.
If crocking is a concern, an initial wash before extended wear, and some caution around light coloured upholstery with brand new dark denim, reduces the risk considerably. See our guide to washing jeans and raw denim guide for more on caring for deeply dyed denim.
