Colour Fastness Testing: Tests, Grades and the Clause to Write

Which test answers which complaint

Each test simulates one way colour is lost in use. Pick the tests from how the product will be worn, washed and stored, not from a habit list. Every method below is on the Tti Labs ISO/IEC 17025 scope (PNAC LAB-022).

The ISO and AATCC methods in the same row answer the same question under different conditions, so their grades need not match. A report is comparable only with a report to the same method and code.

How to read the grades

Two grey scales do the work. The scale for change in colour (ISO 105-A02) compares the tested specimen with the original, and the scale for staining compares the white adjacent fabric before and after. Both run from 5, no visible difference, to 1, a severe difference, with half grades such as 4-5 and 3-4 between them.

A washing or perspiration report gives one change grade and a staining grade for each fibre in the adjacent fabric, for example cotton, polyamide and polyester. The lowest staining grade is the one that matters, because it shows the fibre a garment is most likely to stain in a mixed wash.

Light fastness is the exception. The specimen fades next to eight blue wool references, rated from 1, very low fastness, to 8, very high (Museum of Fine Arts, Boston). ISO 105-B02 allows two different sets of blue wool references whose results may not match, so the report must say which set was used (ISO).

One wash or five: the test code changes the answer

ISO 105-C06 has single (S) and multiple (M) tests. One S test approximates one domestic or commercial laundering. One M test may approximate up to five launderings at no more than 70 °C, and M tests are more severe because they add mechanical action (ISO 105-C06:2010). The letter in the code sets the temperature and conditions, which are listed in Table 2 of the standard. Match the code to the care label: a garment labelled for a 40 °C wash is judged on a test at the same temperature, not a hotter one.

AATCC TM61 works differently. One accelerated 45-minute test roughly approximates the colour loss of five typical hand or home launderings (AATCC). A US buyer who asks for AATCC 61 2A is therefore asking about five washes, not one. ISO 105-C06:2010 is still the current edition and has been confirmed by ISO at review (ISO).

A published benchmark: the OEKO-TEX limits

Buyer limits vary, but one set is public. STANDARD 100 by OEKO-TEX sets minimum staining grades by product class (OEKO-TEX, Edition 02.2025):

Two notes in the same document matter in practice. Articles designed to wash out colour have no rubbing requirement, and pigment, vat and sulphur colourants may pass dry rubbing at grade 3 instead of 4. For pigment prints and sulphur-dyed fabrics, set the rubbing grade deliberately instead of copying a specification written for solid reactive dyes.

These are minimums for a label, not a brand specification. Many brand specifications add washing fastness and wet rubbing, which OEKO-TEX does not set. If the purchase order is silent on either, ask before production, not after a failed report.

Worked example: a navy jersey that passes on colour and fails on staining

In this example report, a navy cotton jersey is tested to ISO 105-C06 A1S against a specification of colour change 4 and staining 3-4. The report reads:

The shirt barely fades, but it stains cotton, the fibre it will meet in every mixed wash. The colour change grade alone would have passed it. The fail sits in the staining row, and that row is what drives returns over white shirts ruined in the wash.

Test the bulk fabric, not only the lab dip

A lab dip proves the recipe. The bulk fabric proves the dyehouse ran it correctly. Test at three points:

• Lab dip or strike-off approval: confirms the dye recipe can meet the grades.

• Bulk fabric, before cutting: confirms the production lot meets them. A failure here costs a re-finish, not finished garments.

• During production: the inspector checks shade against the approved reference. Tti Inspections accepts shade at grade 4 and above at final inspection (Tti Inspections). The DUPRO guide covers the mid-run check.

Test each colourway separately. Each colour is its own dye recipe, and a pass on white says nothing about navy. Denim has its own sequence of wash, shade and shrinkage checks, covered in the denim QC guide.

Checklist: the colour fastness clause in a purchase order

• Each test by method and code, for example ISO 105-C06 A1S or AATCC TM61 2A

• Minimum grade for colour change and for staining, stated separately

• Dry and wet rubbing grades, stated separately

• Light fastness grade, and which blue wool set it refers to

• Which colourways are tested, at minimum every colour on the order

• When samples are drawn: lab dip, bulk fabric, finished garment

• The laboratory and its accreditation scope, with the method listed on it

• What happens on a fail: re-finish and re-test before cutting, at whose cost

For chemical limits such as azo amines, formaldehyde and nickel, see the REACH testing guide; for the full picture of export testing, see the lab testing guide.

Colour fastness testing at Tti Labs

Tti Testing Laboratories in Lahore is accredited to ISO/IEC 17025:2017 under PNAC LAB-022, valid until 8 Aug 2027. The scope covers colour fastness to laundering (ISO 105-C06, ISO 105-C10, AATCC TM61), rubbing (ISO 105-X12, AATCC TM8), perspiration (ISO 105-E04, AATCC TM15), light (ISO 105-B02, AATCC TM16.3), water, water spotting, sea water, dry cleaning, bleach and phenolic yellowing.

The laboratory runs about 1,500 tests a day. Each test and its charge are quoted in writing, with the turnaround confirmed, before work starts (Tti Labs testing). The textiles and apparel page lists the full textile scope.

Request a colour fastness test