How colour fastness is tested and graded
Each property has its own test. The buyer picks the ones that match how the product is used: a bed sheet needs washing and rubbing results, a curtain needs light fastness.
| Property | ISO method | AATCC method |
|---|---|---|
| Washing | ISO 105-C06 | AATCC TM61 |
| Rubbing (crocking), dry and wet | ISO 105-X12 | AATCC TM8 |
| Light | ISO 105-B02 | AATCC TM16.3 |
| Perspiration | ISO 105-E04 | AATCC TM15 |
| Water | ISO 105-E01 | AATCC TM107 |
Colour change is judged with the grey scale in ISO 105-A02 and staining of an adjacent white fabric with ISO 105-A03, both from 1 (severe) to 5 (none), in half grades. Light fastness is rated against blue wool references from 1 to 8, where 8 is the most resistant.
Worked example: navy bed sheets
A buyer orders navy cotton sheets with this line in the specification: washing ISO 105-C06, colour change 4, staining 3–4 minimum; rubbing ISO 105-X12, dry 4, wet 3 minimum. The lab report shows:
- Washing: colour change 4, staining on cotton 3. Fails staining (3 is below 3–4).
- Rubbing: dry 4, wet 2–3. Fails wet rubbing.
Two results are below the agreed minimum, so the fabric does not meet the order even though it looks right. Dark shades usually show this on wet rubbing first. The mill can improve wash-off or fixing and resubmit; a retest on the corrected lot closes the point.
Where it matters
Colour fastness is mostly a contract requirement, not a legal one. It matters for bed sheets, denim, block-printed textiles, dhurries and curtains. Restricted dyes are a separate, chemical question: see azo dyes and restricted substances.
How Clear To Load uses it
On site, the inspector rubs the fabric with dry and wet white cloth and records any staining with photos. That is a screen, not a grade. Graded results need an ISO/IEC 17025-accredited lab: through lab testing coordination we pull and seal samples for the lab you choose or one we suggest, then check the report against the goods. We have no partner labs.