Colorfastness
Also searched as: colourfastness, color fastness, colour fastness, fastness, wash fastness, light fastness, rubbing fastness, crocking, crock fastness, grey scale, gray scale, ISO 105
Colorfastness is a textile's resistance to change in its own color, and to transferring color onto other materials, under a defined exposure such as washing, light, rubbing or perspiration.
In detail
Fastness is always tied to a specific agent and test. Standard methods expose a specimen under controlled conditions, often alongside undyed adjacent fabric, then compare the result with reference standards. Two separate judgments are made: change in shade of the specimen, and staining of the adjacent fabric. Results are expressed as grades on a scale where 5 means no perceptible change and 1 means severe change, with half grades such as 3-4 used between steps. The international ISO 105 series and AATCC methods in the United States are the main frameworks.
The science and numbers
Visual assessment uses grey scales, graded pairs of grey chips representing defined color differences, viewed under standardized lighting and geometry; separate scales exist for change in color and for staining. Lightfastness uses its own reference materials exposed alongside the specimen. Within ISO 105, parts are grouped by letter; for example, ISO 105-X12 covers color fastness to rubbing using a crockmeter. Instrumental grading converts measured color differences into grades, and research using spectral reconstruction and neural networks reports close agreement with trained visual assessors for rubbing stains. Dye chemistry drives outcomes: covalently bound reactive dyes resist washing, mordants improve natural dye fastness, disperse dyes on polyester need sublimation checks, and solution-dyed fibers often reach high grades because pigment is locked in the polymer.
A practical example
A dark red cotton shirt is tested for rubbing: a white test cloth is rubbed across it dry and then wet. The dry test earns grade 4, the wet test grade 2-3. The shirt barely changes color, yet it can mark a light sofa or bag when damp. A single washing grade could not have predicted that: each agent needs its own test.
What to distinguish
A fastness grade applies only to the test method and conditions used; wash grades do not predict light or rubbing performance. Staining and change in shade are separate results. Grades are ordinal, not linear, so a 4 is not twice as good as a 2. Requirements vary by product and buyer, and a garment can be colorfast yet still shrink or pill.
Origins and history
Fastness testing developed as dye chemistry multiplied and buyers needed common language for disputes over fading and bleeding. National textile chemists' associations and international standardization committees built methods and reference scales that could be reproduced between laboratories. Today laboratories commonly report ISO 105 or AATCC grades on test reports. Founding dates of specific organizations and methods were not verified for this edition.
Related terms
Sources & further reading
- Journal of Imaging: Digital grading of color fastness to rubbing per ISO 105-X12 (Liang et al., 2023)
- Scientific Reports: Novel aryldiazenyl disperse dyes on polyester, fastness assessed by grey scale (Omar et al., 2023)
- CottonWorks: Dyeing
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.