superwash

Superwash refers to wool fibers, yarns, or fabrics that have been chemically or mechanically treated to be machine-washable without felting or excessive shrinking. The treatment targets the scales on the wool fiber or adds a protective coating, reducing the fiber-to-fiber entanglement that causes felting when agitated in water. Superwash wool is commonly used in sweaters, socks, and other everyday knitwear because it can be cleaned in a domestic washing machine.

There are two main methods used to produce superwash wool. The chlorine-based method involves treating the wool with a chlorine-containing solution to partially remove or weaken the fiber scales and then applying a protective polymer finish. This combination reduces felting and allows machine washing, though it changes the hand and can affect dye uptake. The polymer-coating method applies a film-forming polymer directly to the fibers, either alone or after a brief scouring. This coating acts as a barrier to prevent the scales from interlocking, enabling machine washability without relying on scale removal. Some modern superwash processes use a polymer finish without chlorine treatment.

Effects and care considerations include a softer appearance and a slightly slicker feel, with possible changes in elasticity and dye behavior compared to untreated wool. Superwash wool remains susceptible to damage from high heat and aggressive agitation, so care labels often recommend cold or warm cycles and air drying or low-heat tumble drying. Environmental concerns have prompted shifts toward chlorine-free or alternative finish methods in some mills, and ongoing research addresses fiber longevity and microplastic shedding.

In practice, superwash wool offers convenient machine washability for woolen goods, while preserving many properties valued in traditional wool.