Fabric testing: what 744 knit fabric lab reports show
GSM and shrinkage are the knit fabric tests that fail most: 42% and 39% of results in our 744 lab reports. Fail…
Does the dryer shrink clothes? Tumble dry vs air dry, from lab data
Yes: a tumble dryer shrinks most clothes more than air drying, most of all cotton. In 744 knit fabric lab reports, 50%…
Skew in knit fabric: how it differs from spirality and bow, how it is tested, and how to prevent it
What bias or wale skew is, how AATCC 179 and ISO 16322 measure it after washing, what limits buyers set, why knits…
Colour fastness to hot pressing (ironing) on knit fabric: test method, results and how to stop wet staining
How the ISO 105-X11 hot pressing test works, how to read dry, damp and wet grades, and why CVC fleece fails on…
Phenolic yellowing test (ISO 105-X18) on knit fabric: method, causes and prevention
Why white and pastel knits turn lemon-yellow in poly bags, how the ISO 105-X18 test predicts it, why CVC blends failed in…
Appearance After Washing Test for Knit Fabric and Garments
How ISO 15487 and AATCC style appearance tests judge colour change, cross-staining, fuzz, seams and shape after home washing, why CVC knits…
How to test clothes for colourfastness at home
Four quick home tests with a white cloth, water and an iron show whether clothes will bleed in the wash, rub off,…
Why fleece and sweatpants pill, and how to stop pilling
Pills form when surface fibres rub up and tangle; polyester holds them on. Why fleece, terry and sweatpants pill most, what our…
How to test the GSM of knit fabric: method, tolerances and real lab results
How the lab measures fabric weight (GSM), step by step, with the formula, a worked example, the tolerances buyers use, and what…
How to test shrinkage of knit fabric: dimensional stability method, limits and real results
How the lab measures shrinkage after washing, step by step (ISO 3759, ISO 6330, ISO 5077), with the formula, a worked example,…
About Testing
Every dyed fabric has to pass tests before it ships. The most common are colour fastness (to washing, rubbing, light, perspiration and water), dimensional stability (shrinkage and spirality after washing), physical tests such as GSM, pilling and bursting strength, and chemical tests such as pH.
The articles here follow public test methods from ISO and AATCC and explain them from the dye house side: which process step controls each result, and what we change when a test fails. A poor rubbing result on a dark shade, for example, usually goes back to the wash-off or the reduction clear, not to the test itself.
Questions about testing
How is colour fastness rated?
Fastness is rated on a grey scale from 1 to 5, where 5 means no change or no staining and 1 means a severe change. Light fastness uses a separate blue wool scale from 1 to 8.
What is the difference between wash fastness and rubbing fastness?
Wash fastness measures how much a fabric changes colour and stains other fibres in washing. Rubbing fastness measures how much colour rubs off onto a white cloth, dry and wet. Deep shades usually find wet rubbing the hardest to pass.
What causes a knit fabric to fail a shrinkage test?
Mostly the fabric was stretched in finishing and not given enough overfeed or compaction, or the construction itself is unstable. Fixing it in finishing works only up to a point. Large problems need a change in knitting.