quality · 5 min read

Colour fastness: the four tests that matter and what the numbers mean

Colour fastness is not one property. A fabric can survive washing perfectly and still bleed onto a white bag in the rain. Each test measures a different failure.

By Weft Bridge · Reviewed by our Guangzhou sourcing team · Updated 2026-11

The four tests

Test	Measures	Typical standard	Common minimum
Washing	Colour loss and staining after laundering	ISO 105-C06 / AATCC 61	4–5 change, 4 staining
Rubbing (crocking)	Transfer onto another surface	ISO 105-X12	4 dry, 3–4 wet
Light	Fading under exposure	ISO 105-B02	4–5 for apparel
Perspiration	Bleeding in sweat	ISO 105-E04	4

How to read a rating

Ratings run from 1 to 5 in half steps, judged against a grey scale. Five means no change; one means severe change. A result of 4–5 is close to no visible change in normal use.

Always ask which standard and which test condition. A washing test at 40 degrees is not the same as one at 60, and a light test at 20 hours is not the same as 40.

Where it goes wrong

Dark shades, especially reactive blacks and navy, crock more than light shades.
Bright reds and oranges fade under light faster than other colours.
Cheap pigment prints can fail wet rubbing even when washing passes.
A fabric that passes as a flat piece can fail at a seam, where abrasion is higher.

FAQ

Is 4 good enough?

For most apparel, yes. For babywear, swimwear or workwear, ask for 4–5 and test the actual conditions of use.

Who pays for the test?

Usually the buyer, unless the mill already has a report for that quality. Reports are article-specific, not generic.