Definition and evaluation system of color fastness
Color fastness, also known as dyeing fastness or dyeing resistance, refers to the resistance of a textile's color to various external influences during processing and use. The fastness grade is evaluated based on the color change of the sample and the staining of the undyed adjacent fabric. Textile color fastness testing is a routine inspection item in assessing the intrinsic quality of textiles. During their service life, textiles are exposed to various external factors such as light, washing, ironing, perspiration, friction, and chemicals. Some dyed and printed textiles also undergo special finishing treatments, including resin finishing, flame retardant finishing, sand washing, and sanding. Consequently, the color of dyed and printed textiles is required to maintain a certain level of fastness. Color fastness, in short, is the resistance of colored fibers, fabrics, or other colored materials to fading or discoloration when subjected to various environmental factors such as sunlight, washing, friction, perspiration, and other corrosive agents during processing and use. Except for light (sunlight) fastness, which is rated on an 8-grade scale (R grade), other fastness grades are rated on a 5-grade scale. A higher grade indicates better color fastness.
Special testing method for color fastness of leather
For leather testing, there are two methods: fading (color change of the leather itself) and staining (color transfer to contacting materials). The fading test involves comparing the color difference between a treated leather sample and an untreated sample under specified conditions, and rating it against a standard gray scale. The staining test evaluates the degree of color transfer from the sample to a standard white fabric under specified conditions, which is measured using a gray staining scale.
The phenomenon and mechanism of color transfer in clothing
Color migration can occur in garments composed of different colored parts during storage, typically from darker areas to lighter ones. This phenomenon, distinct from sublimation, occurs below sublimation temperatures and can also involve non-sublimation dyes. It is particularly evident in polyester and other synthetic fabrics, although it can also occur in other materials. Color migration is primarily attributed to two factors: first, dye transfer, especially from floating or migrated disperse and reactive dyes, which may redeposit onto the surface of another sample, particularly from darker to lighter shades, resulting in granular or imprinted stains on the sample surface; second, fiber loss due to friction, where fibers transfer from one sample to another.
