The Superwash Treatment Superwash treatment of wool is the reduction of shrinkage and pilling. It works on the basis of chlorination and subsequent coating of the fibre material with a polyaminoamide. The use of chlorine serves to reduce the scale structure and allows the resin to adhere to the surface of the wool fibre. The result is a huge reduction of the friction between the fibres and therefore the amount of shrinkage and pilling. It is important to understand that this is a shrink resistant process, rather than shrink proofing.