Colour fastness: what the grades mean
Fastness is graded 1 to 5 against a grey scale, where 5 is no change and 1 is severe. It is measured separately for washing, rubbing (dry and wet), light and perspiration, because a dye can be good at one and poor at another.
For a retail t-shirt the useful floor is grade 4 for wash and grade 4 for wet rub. Below that, a customer in a hot climate will see colour on a light garment or a faded panel within a few washes.
- Grade 5 — no visible change. Rare outside very well-fixed dyes.
- Grade 4 — slight change, acceptable for retail.
- Grade 3 — noticeable change. Fine for a giveaway, not for retail.
- Grade 2 — significant change. A complaint waiting to happen.
- Grade 1 — severe. The dye is not properly fixed.
What causes poor fastness
Dye class mismatch: reactive dyes fix chemically to cotton and hold well; pigment dyes sit on the surface bound by a binder and rub off. Sulphur dyes on black are cheap and notorious for wet rub.
Insufficient washing-off after dyeing. Residual unfixed dye is what bleeds in the customer’s machine, and it is the failure that shows on the very first wash.
Water hardness and pH at dyeing. The same recipe on different water produces different fixation, which is why the same colour from two mills is not the same colour in service.
Pilling: what the rating means
Pilling is graded 1 to 5 after a standard abrasion test, where 5 means no pills and 1 means heavy pilling over the whole surface. Retail knitwear usually specifies 4 or better after a set number of cycles.
The cause is mechanical: short fibres work loose, tangle, and form balls. Anything that increases short fibre content or surface friction makes it worse — open-end yarn, loose knits, and fabric with a brushed face.
The two are linked more often than buyers expect
A fabric that pills also looks faded, because the pills scatter light differently and the surface stops reflecting evenly. Customers report it as colour loss even when the dye is intact.
That is why a programme complaining about fade should check pilling first: the fix may be yarn and knit, not the dyehouse.
What to put in the purchase order
Write the numbers, not the adjectives: "colour fastness to washing grade 4 minimum, wet rub grade 4 minimum, pilling grade 4 minimum at 2,000 cycles". Those are measurable in a lab and comparable between suppliers.
Also specify the test method, because the same name can mean different cycles. Without it, two suppliers can both be "grade 4" on tests that are not the same test.
Fade and pilling are the two failures the customer sees, and both are numbers that can be written into a purchase order before anything is cut.