Fabric guide
Which test answers which question about a fabric, the standard methods most often named, and how to write a test requirement that a laboratory and a supplier can both follow.
In short
Fabric testing turns a description into a number. Each property has its own test: dimensional change, colourfastness to washing, rubbing and light, pilling, abrasion, tensile and tear strength, seam strength. The test method, the conditions and the pass limit all have to be written down, because two laboratories using different methods get different results.
9 min read
Written by the AHM International product development team
Updated October 2026. Every worked figure is checked by automated tests.
Why test, and what a test is not
A fabric description is a promise; a test is evidence. "Colourfast" means nothing until it is tied to a method, a wash condition and a grade. Testing is how a specification becomes something that can be accepted or rejected without an argument.
A test is also narrow. It measures one property under defined conditions on the sample that was tested. It does not describe the next production lot, and it does not replace inspection of the finished garment.
Which test answers which question
Examples of widely used methods, named so a buyer can ask for one. The edition and the method your own contract, brand or retailer requires are the ones that govern, and a laboratory can advise on equivalents.
| Property | The question | Methods commonly named | Buyer note |
|---|---|---|---|
| Mass per area (GSM) | Is it the weight that was approved? | ISO 3801, ASTM D3776, EN 12127 | Say whether the weight is before or after finishing |
| Dimensional change | How much does it shrink or grow after laundering? | ISO 6330 for the wash procedure with ISO 5077 for measurement; AATCC 135 | Length and width separately; state the number of washes |
| Colourfastness to washing | Will the colour run or fade in the wash? | ISO 105-C06; AATCC 61 | Both staining of other cloth and colour change are graded |
| Colourfastness to rubbing | Will colour transfer onto skin or other garments? | ISO 105-X12; AATCC 8 | Dry and wet rubbing give different results |
| Colourfastness to perspiration | Does colour change with sweat? | ISO 105-E04 | Relevant for sportswear and workwear worn hard |
| Colourfastness to light | Will it fade in daylight? | ISO 105-B02 | Matters for outdoor and window-exposed uniforms |
| Pilling | Will it form bobbles with wear? | ISO 12945-2, ASTM D4970 | Graded after a number of rubbing cycles |
| Abrasion resistance | How long before it wears through? | ISO 12947 (Martindale), ASTM D4966 | Report the cycles to a specified end point |
| Tensile strength | How much force before it breaks? | ISO 13934-1 | Warp and weft differ |
| Tear strength | How easily does a tear spread? | ISO 13937, ASTM D1424 | Finishes such as easy-care can reduce it |
| Seam strength and slippage | Do seams hold or pull open? | ISO 13935, ISO 13936 | A fabric can pass and its seam still fail |
How to write a test requirement
- 01
Name the property and the method
"Shrinkage per ISO 6330" is a requirement. "No shrinkage" is not.
- 02
State the conditions
The wash temperature and cycle, the drying method, the number of washes, and whether the test is on fabric or on the finished garment.
- 03
State the pass limit
A number with its tolerance, for example a maximum dimensional change in length and in width, or a minimum colourfastness grade.
- 04
Say who tests, and who pays
Whether the supplier's laboratory, an independent one, or the buyer's nominated laboratory is the reference, and who bears the cost on a failure.
- 05
Ask for an accredited laboratory
ISO/IEC 17025 is the international standard for testing laboratory competence, and an accredited laboratory's report states its scope.
- 06
Test the production, not just the sample
Agree how many lots and how often. The approved sample says what a lot can be, not what every lot is.
What a fabric test does not tell you
- How the garment will fit after washing
- Fabric shrinkage is a start; sewing, pressing and finishing change the garment's own dimensional change.
- Whether a program will be happy
- Wear, wash conditions and handling in real use differ from a laboratory cycle. A wear trial is evidence that a method cannot be.
- That a claim is certified
- Flame, chemical and high-visibility performance need certification to the relevant standard, not a general test result.
- AHM's own testing
- Whether a given test is carried out in-house or by an external laboratory is a question to ask any supplier, and AHM's answer for your program is part of the commercial discussion.
Work the numbers
Try it on your own fabric.
Related questions
ISO methods are international standards used widely in Europe and Asia; AATCC methods are published by a US textile association and are common in North American specifications. They differ in procedure, so results are not interchangeable. Use the one your buyer names.
Marked fabric or garments are washed and dried by a defined procedure, then re-measured and the change reported as a percentage in length and width. The wash cycle, drying method and number of washes change the result.
Fastness to washing, rubbing and perspiration is graded on a 1 to 5 scale, where 5 means no change or no staining; fastness to light uses a separate 1 to 8 scale. A requirement states the minimum grade for each test.
That is a commercial term to agree in advance: who commissions it, which laboratory is the reference, and who pays on a failure.
Send one specification and we will apply exactly this thinking to your style. Construction, materials and commercial FOB costing.