What is Color Fastness?

Color fastness (colorfastness) is how well a dyed or printed textile keeps its color when exposed to washing, rubbing, perspiration, light and similar factors. Both the change in the textile's own color and the staining of other fabrics are measured. The result is a grade, 1–5 on the gray scale or 1–8 on the blue wool scale depending on the method; a higher grade means better fastness.

What is color fastness?

ISO 105-A01 defines color fastness as the resistance of a textile's color to the agents it meets during manufacture and use. A change in the color itself and staining of the adjacent undyed fabric count as the fastness grade; luster change or shrinkage are separate properties and are reported separately (EVS record of ISO 105-A01:2010). ISO titles spell the term “colour fastness”; US methods such as AATCC's write “colorfastness”.

Types of color fastness

Color fastness is a family of tests, one per agent. The most requested are these:

Separate parts exist for dry cleaning (D01), hot pressing (X11) and washing with oxygen bleach (C09). A specification that says only “oxidative fastness” should name the standard. ISO 105-C09 measures the change in tone when washing with an oxygen-bleach reference detergent, applies to all textiles except wool and silk and does not assess staining (AFNOR); that the term maps to one standard part could not be verified, so ask the laboratory to confirm it in writing.

In the US, AATCC methods are used. TM61 imitates about five washes in one test and the S test of ISO 105-C06 about one wash, so do not compare grades from the two methods directly. For how the tests are run, see the fabric testing standards guide.

How to read a color fastness grade

Color change and staining are graded by eye with gray scales: 5 means no difference and 1 means the largest difference. With the half grades (4-5, 3-4, 2-3, 1-2) the scale has nine steps. ISO's part for the color change scale is A02 and for the staining scale A03. In washing and perspiration tests, staining is read on an undyed adjacent fabric held in contact with the specimen, often a multifiber adjacent fabric (ISO 105-F10). Because the assessment is visual, two assessors can differ by half a grade (Özkan and Oğulata, 2018, a Turkish study); ISO 105-A05 instead measures color change with an instrument and converts it into a gray scale grade.

For light fastness, the specimen is exposed together with blue wool references numbered 1–8. A higher number means more resistance to light, and each step needs roughly 2–3 times as much light to cause the same fading (Canadian Conservation Institute).

There is no single universal threshold; a numeric minimum comes from the buyer's specification or a certificate. As an example, GOTS 8.0 (a voluntary standard, published in March 2026 and applying from March 1, 2027) asks for these minimum grades on GOTS-labeled final consumer products (Table 7, accessed October 22, 2026):

What does color fastness depend on?

The fiber, the dye class, the depth of shade and the steps after dyeing act together. Dark shades are tested harder. In one study of reactive-dyed cotton knit fabric, light pink scored 4-5 in wet rubbing, while dark black scored 2-3 with the conventional process and 4 with a cationic pretreatment, salt-free process (Ghosh and Rupanty, 2023; one study of one dye class, so do not generalize). Fastness is related to after-treatments as much as to the dyeing method (Özkan and Oğulata, 2018), so have the test run on a specimen taken from the finished fabric. The entries on denim (indigo wears off the surface), sublimation printing (high fastness on polyester) and mercerization (higher dye uptake) give more detail.

How to specify color fastness in an order

1. Choose the agent: for garments, washing, rubbing and perspiration come first; for curtains and upholstery, light fastness stands out (our recommendation).
2. Write the standard, edition and condition: for example “ISO 105-C06:2010, A1M”. Editions are replaced: ISO 105-X11 moved to a new edition in 2026 (EVS).
3. Ask for separate grades: one minimum for color change and one for staining, and separate minimums for dry and wet rubbing.
4. Set the minimum by end use: if a certificate or brand specification applies, use its table as the baseline.
5. Take the specimen correctly: from the finished fabric, in the same color and finish as the order. Textile testing laboratories or the dye house's own laboratory can issue the report; the standard and condition must be written on it.

What color fastness is not

• Fading and staining: color change is the specimen's own color changing, staining is color moving onto another fabric; they have separate scales and separate grades.
• Color consistency: two lots of a high-fastness fabric can still come out in different shades; shade difference between lots or within a roll is not measured by a fastness test.
• Swatch cards and lab dips: they show whether a color matches, not how fast it is; see the swatch card entry.
• Other performance properties: shrinkage, pilling and abrasion are not fastness.

Frequently asked questions

What is a color fastness grade?

It is the result of a fastness test: color change and staining are graded 1–5 and light fastness 1–8, and a higher number means better fastness.

What is wet rubbing fastness?

It is fastness tested in wet conditions. In ISO 105-X12, a dampened standard cloth is rubbed on the specimen and the color that transfers is graded. Washing (C06) and water (E01) tests are also run wet. A wet rubbing grade is often lower than the dry one; GOTS 8.0 asks for 3-4 dry and 2 wet.

What is light fastness?

Light fastness is a color's resistance to fading in daylight (ISO 105-B01) or under a xenon arc lamp (B02); it is graded 1–8 on the blue wool scale.