How the lab tests colour fastness to water (ISO 105-E01), step by step, how it is graded, and what 47 real lab tests on knit developments showed.
About this guide. The method below is written from the public ISO and AATCC standards in plain words. The data comes from our own lab reports on 95 new knit developments, each tested by an accredited lab to the buyer’s standard, so you can see what real results look like.
At a glance
47Water fastness tests in our data
95%Passed
37°C × 4 hTest condition
3-4 or 4Usual staining minimum
What the test measures
Colour fastness to water shows whether plain water makes a fabric bleed: a wet swimsuit, a garment left damp in a bag, rain on a dark jacket over a light shirt. It is the simplest wet fastness test and often the first to show loose dye.
Equipment
The same as the perspiration test: a perspirometer with plates, an oven at 37 ± 2°C, multifibre adjacent fabric, the grey scales and a viewing cabinet, with grade 3 water (distilled or deionised) instead of perspiration solution.
How the test is done, step by step (ISO 105-E01)
- Prepare a composite specimen: 100 × 40 mm of fabric sewn to the same size of multifibre strip.
- Soak it in water at room temperature until fully wetted.
- Remove the excess water, then press the composite between plates under 12.5 kPa.
- Keep it in the oven at 37 ± 2°C for 4 hours.
- Separate and dry at no more than 60°C, touching only at the stitching.
- Assess colour change and staining with the grey scales.
Grading: the two grey scales
Two results are reported. Colour change compares the tested specimen with an untested piece of the same fabric, using the grey scale for colour change. Staining compares each band of the multifibre strip with an unused strip, using the grey scale for staining. Both run from 5 (no change, no staining) to 1 (severe), in half grades, and are assessed in a viewing cabinet under daylight (D65).
The multifibre strip has six bands: acetate, cotton, nylon, polyester, acrylic and wool. Each band shows whether the dye that came off would mark that kind of fibre in a mixed wash or in a garment made of different fabrics.
Some of our reports used AATCC 107, which runs 18 hours at 38°C.
Example result. “Change 4; staining: cotton 4, nylon 3-4, others 4-5.” Against a minimum of staining 4, it fails on nylon.
What real results look like
45 of 47 batches passed. Colour change rarely decides the result; it is the staining, usually on the nylon band, that fails.
| Fabric | Failed |
|---|---|
| With polyester | 1 of 14 |
| Without polyester | 1 of 33 |
Fabrics with polyester fail more often: the disperse dye on the polyester part stains nylon, polyester and acetate if it is not fully reduction cleared, or if the fabric is finished too hot and the dye moves back to the surface.
If a batch fails, see why knit fabric fails staining: 9 real cases.
Common mistakes that change the result
- Using tap water instead of distilled or deionised water.
- Letting the specimen dry out in the oven: keep the plates loaded and the time exact.
- Leaving too much water on the specimen before pressing.
From the floor
- Water fastness fails come on deep shades with loose dye left in the fabric.
- For cotton, soap twice at 80°C, give hot washes at 70°C and 60°C, and check a sample against white fabric before fixing and unloading. For polyester, reduction clear twice and never finish above 100–110°C.
Questions
What is the difference between water and perspiration fastness?
The method is the same; water fastness uses plain water instead of acid and alkaline perspiration solutions.
Why does nylon stain in a water fastness test?
Nylon takes up loose dye easily even in plain water, so it shows any dye that was not washed off or fixed.
Textile engineer with 14+ years in dyeing and fabric development. He writes every guide on Dyeing Solution from real production work. Full profile