Sweater Colour Fastness: Why Colours Bleed and How Buyers Control It

By YZR Sweaters · 2026-09

Colour fastness is the property most likely to turn a good-looking sweater into a complaint — and one of the cheapest risks to manage. It can be specified, sampled and tested before bulk starts.

What does colour fastness actually measure?

Colour fastness is the resistance of a dyed yarn or garment to losing colour, or to transferring colour onto something else. It is not one property but a family, and each one matches something that happens to a sweater in wear.

Fastness to washing (wash fastness)

Wash fastness covers two events: the garment's own shade changing after laundering, and colour staining whatever is washed with it. It matters most for light colours in mixed home washes and for styles a customer machine washes.

Fastness to rubbing (crocking)

Rubbing fastness, also called crocking, measures how much colour transfers when the fabric is rubbed against another surface. It is assessed both dry and wet; wet crocking is the harder test, because moisture lets dye migrate. It is the number that predicts a stained white shirt.

Fastness to perspiration, light and water

Perspiration fastness tests colour transfer under sweat, so it matters for anything worn against the skin. Light fastness covers fading in a shop window or summer sun, and water fastness checks bleeding when a garment gets wet without being laundered.

Which fibre and colour combinations carry the most risk?

No supplier can promise a shade will never bleed, but the risk pattern is well understood and useful when choosing a range — the fibre itself sets how much dye it will hold and how firmly, as our sweater yarn guide explains.

• Deep and saturated shades — blacks, reds, royal blues and deep greens carry more surface dye than pale shades and appear most often in complaints.
• Cellulosic fibres — cotton and viscose take reactive dyes, which bond well but leave unfixed dye on the fibre unless rinsing is thorough.
• Protein fibres — wool and other animal fibres take acid dyes, and deep shades often show weakness on wet rubbing.
• Blends — where two fibres absorb dye at different rates, colour looks uneven and migrates more easily.
• Skipped or short washing — floating dye left on the fibre fails fastness however good the recipe was.

Why do classic “dark jeans stain a white shirt” accidents keep happening?

That failure is rarely one fault. A saturated shade worn against the body combines wet rubbing with perspiration, and moisture carries dye from the dark surface to the pale one. Knitwear adds its own version: yarn sits on the surface and moves with every arm movement, so a knit works against a bag strap or seatbelt far more than a woven shirt would.

How do you write colour fastness into the order?

Instructions such as “good colour fastness” are how disputes start. Specify requirements in the tech pack, in terms a laboratory and a factory both recognise.

• Name the tests that match the wear — children's knitwear needs wash and perspiration fastness; deep-coloured wool needs wet crocking; a summer viscose top facing shop windows needs light fastness.
• State the method and the grade — normally the applicable ISO or AATCC method, with minimums agreed separately for shade change and for staining. Confirm the current method and grading scale with your lab.
• Require reports, not assurances — laboratory results run on the bulk dye lot before shipment.
• Approve the shade against a physical standard — a lab dip or colour hanger retained by both sides.
• Say what happens on a failure — re-test, re-wash, sort or reject, and who pays.

How should colour fastness be verified before shipment?

Evaluate at sampling, confirm at pre-production and test the bulk — washing and rubbing the actual production dye lot, not a lab dip made months earlier under ideal conditions. Third-party verification from SGS or BV gives you a report a retailer will accept; our notes on sweater lab testing explain how results are reported. Retain a sealed sample from every bulk lot, labelled with its dye lot number.

What should you do when a bleeding complaint arrives?

First separate two situations. A batch that fails a requirement the order already set is the supplier's problem, handled through re-testing, rework, sorting or a claim. A product that met a specification set too low for how the garment is worn is the specification's problem, fixed on the next order.

Then distinguish normal fading from a defect. All dyed textiles lose colour over time, so a sweater fading gradually across a season is normal; a white shirt stained pink after one wash is not. Ask about wash temperature and detergent, because a hot wash can defeat a reasonable grade. Where a claim is justified, the retained lot sample is normally re-tested first.

How can you reduce the risk at the sourcing stage?

• Steer the design away from the riskiest combinations where the range allows — an off-black or softened red is easier to control than a maximum-saturation shade.
• Require a thorough rinse and finishing wash, and question any quote that removes it.
• Ask which dyehouse will run the shade, and keep that dyehouse for reorders.
• Confirm shade and wash performance on a sample, before a problem costs a container.
• Weigh the dyeing route for colour-blocked designs, where yarn dyeing versus piece dyeing gives different stability.

Our Dongguan workshop runs OEM/ODM knitwear programmes for brands, wholesalers and online retailers, working with BSCI, SEDEX and Oeko-Tex certified partner factories that welcome audits and third-party inspection, and coordinates colour fastness evaluation at sampling.

Frequently asked questions