Colorfastness

Color fastness, also known as dyeing fastness or color durability, refers to the resistance of a textile’s color to various factors during processing and use.

The fastness grade is determined based on the color change of the test specimen and the staining of the uncolored backing fabric. Textile colorfastness testing is a routine quality-control procedure in the assessment of textile intrinsic quality.

During their use, textiles are subjected to various external factors, including exposure to light, washing, ironing, sweat stains, friction, and chemical agents. Moreover, some printed and dyed textiles undergo special finishing processes, such as resin treatment, flame-retardant finishing, sandblasting, and napping, which necessitates that the color of these textiles maintain a certain degree of colorfastness.

Color fastness

Color fastness, often simply referred to as color fastness, refers to the resistance of the color of dyed fibers, fabrics, or other colored materials to various forms of degradation—such as exposure to sunlight, washing, rubbing, and sweat—during processing and use.

With the exception of lightfastness (resistance to fading under light exposure), which is rated as Grade R, all other colorfastness ratings are Grade 5. The higher the grade, the better the colorfastness. Leather colorfastness testing encompasses two types: fading (change in the leather’s own color) and staining (transfer of color to contacting materials).

The colorfastness test involves subjecting a leather sample to specified conditions and then assessing the color difference between the treated sample and an untreated control sample, with grading determined by comparison against a standard gray scale. The staining test entails bringing the sample into contact with a standard white cloth under prescribed conditions; the degree of color transfer and staining on the white cloth is evaluated and graded using a gray staining scale.

Colorfastness to rubbing

Garments composed of sections in different colors may, during storage, experience dye migration from one area to another—typically from darker to lighter areas. This phenomenon differs from sublimation because it occurs at temperatures below the sublimation point and can occur even with non-sublimable dyes. It is most commonly observed in synthetic fabrics such as polyester, though it can also occur in other raw materials.

Color transfer is primarily caused by two factors: first, dye migration—particularly the floating color from disperse and reactive dyes, as well as dye that has migrated from within the fibers and become free—can deposit onto the fibers on the surface of another sample; this is especially pronounced when dark colors stain light-colored fabrics, resulting in particle-like or impression-like residues on the surface of the second sample. Second, fibers may detach under the action of friction and transfer from one sample to another.