Washfast

Washfast refers to the resistance of dyed or printed textiles to color loss or transfer during laundering. It is a key aspect of colorfastness and is typically assessed through standardized washing tests that simulate domestic or industrial laundering. These tests evaluate two main components: color change of the test fabric and staining of adjacent unwashed fabrics. Results are reported using rating scales such as the Gray Scale for Color Change and the Gray Scale for Staining, or via numerical grades in established methods. The higher the rating, the better the washfastness.

Several factors influence washfastness. The fiber substrate (cellulose, polyester, blends) affects dye uptake and binding. The dye type and its affinity or chemical bonding to the fiber (reactive, vat, disperse, direct dyes) play a major role. The presence of binders or mordants, and finishing steps such as resin binders or cross-linking treatments, also impact performance. Washing conditions, including temperature, pH, and detergent formulation, can significantly alter outcomes. Pigments used in printing typically require resin binders to achieve good washfastness, while dyes that form strong chemical bonds on the fiber generally exhibit higher resistance when properly fixed.

In textile production, washfastness is a standard specification for consumer textiles, influencing consumer satisfaction and product life. Standards and test methods from organizations such as AATCC and ISO provide procedures to quantify and compare washfastness across products and processes.