Why Uniforms Fade: Colour Fastness and Hot Washing

What colour fastness means

Colour fastness is a fabric's resistance to losing colour. It is measured separately against several forces: washing, light, rubbing (crocking) and perspiration. A fabric can be strong against one and weaker against another, which is why a uniform washed daily needs high wash fastness specifically.

Each of these is checked with its own test: a swatch goes through a standard wash, light-exposure or rubbing cycle and the colour change is scored on a numbered grey-scale, typically 1 (poor) to 5 (excellent). Asking for the grade behind a "colour-fast" claim, rather than the word alone, is how you tell a tested fabric from an untested one.

For institutional wear that means specifying a fabric engineered and tested for repeated hot laundering, not just any dyed cloth.

The test methods behind a fastness grade

A grade only means something if you know which test produced it. Internationally the methods sit in the ISO 105 series. It is split into parts by the force being tested, so a fastness clause names the part, not the series. These are the parts an institutional uniform buyer meets most often.

Two further parts are not tests but the scales used to read them. ISO 105-A02 is the grey scale for change in colour, the 1 to 5 scale quoted above. ISO 105-A03 is the grey scale for staining, which rates how much colour moved onto the fabric next to it, not how much the specimen itself changed. A wash test therefore gives two separate numbers, and a specification that asks for only one leaves the other unstated.

One trap is worth knowing. Light fastness under ISO 105-B02 is rated against blue wool references on a 1 to 8 scale, while the grey scales run 1 to 5. So a light fastness of 6 and a wash fastness of 5 cannot be compared, and neither is a mistake. Read every grade against the scale its own method uses. Confirm the current edition of the standard before quoting it, and write the part, the scale and the minimum grade together. A grade quoted on its own cannot be checked or enforced.

Why uniforms lose colour

• Hot, frequent washing: the biggest cause in medical, hospitality and housekeeping wear.
• Harsh detergents and bleach: strip dye faster, especially on darks.
• Direct sunlight: UV breaks down dye during outdoor wear and line drying.
• Rubbing (crocking): friction at cuffs, collars and seats lifts surface dye.
• Perspiration: sweat and body oils attack some dyes over time.

Choosing fabric that holds its colour

Poly-viscose blends hold dye through industrial laundering better than untreated cotton, which is why uniform programs favour them. Look for a stated wash-fast finish on the spec sheet, and for outdoor roles factor in light fastness too.

Dark and deep shades show fading sooner than mid-tones. So where a role involves heavy laundering, a mid institutional shade in a wash-fast PV blend is the safest choice.

Laundering to make colour last

• Wash cooler where hygiene rules allow; heat accelerates dye loss.
• Turn garments inside-out to protect the outer surface from rubbing.
• Use a mild detergent and avoid chlorine bleach on coloured fabric.
• Dry in shade rather than direct sun to limit UV fade.
• Wash like colours together and avoid overloading the machine.

Benny Cotts fabrics built for the wash

Our suitings are wash-fast poly-viscose blends engineered for institutional laundering. Officer Choice and Sonata hold their shade through repeated washing, and soft-handle Benzzi suits front-of-house roles where appearance must last. For clinical and housekeeping wear, where hot washing is constant, wash fastness is the spec that matters most.

FAQ

Frequently asked questions

Why do dark uniforms fade faster?

Deep dark shades carry more dye at the surface, so any loss shows sooner. A wash-fast blend and cooler, inside-out washing slow it considerably.

Does hot washing always cause fading?

Heat speeds up dye loss, but a fabric made wash-fast for institutional laundering resists it far better. Where hot washing is required for hygiene, specify high wash fastness.

Is poly-viscose more colour-fast than cotton?

Generally yes. PV blends hold dye through repeated hot washing better than untreated cotton, which is a key reason uniforms use them.

Which fabrics do you recommend for heavy laundering?

Wash-fast PV suitings such as Officer Choice and Sonata for structured wear, and soft-handle Benzzi for front-of-house roles. All are engineered for institutional wash cycles.

What does the colour fastness grading scale actually mean?

Fastness is graded on a 1 to 5 grey-scale, where 5 shows almost no colour change and below 3 shows visible fading within normal wash cycles. For institutional wear washed hot and often, look for a grade of 4 to 5 rather than accepting an untested colour-fast claim on its own.

Does sunlight fade uniforms the same way washing does?

No, light fastness and wash fastness are tested and rated separately. UV exposure breaks down dye over time through outdoor wear and line drying, so roles that spend time outside need a fabric checked for light fastness in addition to wash fastness.

Which standard covers colour fastness testing?

Internationally it is the ISO 105 series, divided into parts by what is being tested. ISO 105-C06 is for domestic and commercial laundering, ISO 105-B02 for artificial light, ISO 105-X12 for rubbing, and ISO 105-E04 for perspiration. The grey scales used to read the results are also parts of the series: ISO 105-A02 for change in colour and ISO 105-A03 for staining. A fastness clause should name the part, not the series, because the series alone does not say which force was tested. Editions are revised, so confirm the current one before quoting it in a tender.

Is a light fastness grade of 6 better than a wash fastness grade of 5?

They are not on the same scale, so the two numbers cannot be ranked against each other. Light fastness under ISO 105-B02 is rated against blue wool references from 1 to 8. The grey scales for change in colour and staining run from 1 to 5. A 5 on a grey scale is the top of that scale, but a 6 on blue wool still has two steps above it. Always read a grade together with the method that produced it.

What fastness grades should a uniform specification ask for?

A workable minimum for institutional uniform fabric is: grade 4 or better for colour change and staining in washing (ISO 105-C06); grade 4 for dry rubbing and 3 to 4 for wet rubbing on very dark shades (ISO 105-X12); grade 4 for perspiration (ISO 105-E04); and 4 to 5 on the blue wool scale for light (ISO 105-B02). Name the method next to every grade. Set the wash test temperature to the one your laundry actually runs. Ask for the report before the order is awarded, not after.