How to Read a Fabric Test Report: Colour Fastness, Shrinkage, Abrasion and Water Resistance

Every bulk order begins with a test report, and most sourcing disputes end with one. The report tends to be read only for the columns that look familiar, while the specification it is measured against was never written down. This guide covers the tests that decide woven polyester and nylon programmes, what each number means, and how to turn those numbers into a specification a mill can hit.

What a Test Report Proves — and What It Does Not

A test report is a snapshot of one specimen, tested by one method, on one date. It proves that a specific piece of fabric met or missed a defined threshold under defined conditions. It does not prove that every roll in the shipment behaves the same way, and it does not replace inspection. Treat it as the measurable clause of the contract, not a warranty on the goods.

Two cautions follow. Method matters as much as result, and the report always names its specimen — lab dip, bulk sample or production roll.

The Four Test Families That Decide Most Programmes

For dyed and printed synthetic wovens, a small group of tests carries most of the specification risk:

• Colour fastness — how colour survives washing, rubbing, light and perspiration.
• Dimensional stability — how far the fabric moves in the wash.
• Abrasion and surface behaviour — how the fabric wears, pills and snags.
• Water resistance — pressure resistance plus surface repellency.

Tensile, tear, seam slippage, air permeability, pH and formaldehyde matter to specific end uses; this guide covers the core four and flags the rest where they matter.

Colour Fastness: Four Tests, Four Failure Modes

Colour fastness is a family of tests, each simulating a different way a garment loses colour — and a fabric can pass one comfortably while failing another badly.

Washing (AATCC 61, ISO 105-C06)

Accelerated laundering compresses multiple home washes into one short cycle. Results are reported as a grade for colour change and a grade for staining of the adjacent multifibre strip, on a five-step grey scale where 5 means no change; grades are given in half steps, so 4–5 is a stronger claim than 4. Failures appear as fading in the bulk or as colour bleeding onto trim and labels, which is why the staining column deserves as much attention as the change column.

Rubbing (AATCC 8, ISO 105-X12)

The crockmeter measures colour transferred to a white cloth under dry and wet rubbing. The wet result is the one to watch on deeply dyed shades and on any fabric with a raised or pigment-printed surface. Deep navy, black and saturated reds on disperse-dyed polyester are the classic risk area; the answer is dye selection and after-treatment, not a relaxed threshold.

Light (AATCC 16, ISO 105-B02)

Light fastness is reported after a defined xenon-arc exposure — commonly a fixed number of AATCC Fading Units — on a five-step scale, while ISO 105-B02 reports against an eight-step reference scale. The two are not interchangeable, so read the method line before comparing quotations. Sun-exposed outdoor programmes need this test most.

Dimensional Stability: Shrinkage Is a Specification, Not a Surprise

Home-laundering tests report length and width change as a percentage, with a plus sign for growth and a minus sign for shrinkage, against a stated wash procedure, temperature and drying method. On woven polyester and nylon the finishing route — heat setting, relaxation and controlled dimensional treatment at the mill — holds the number, and it cannot be corrected later in the garment factory.

ISO 6330 defines the wash procedures and ISO 5077 the measurement; AATCC 135 covers fabric while AATCC 150 covers garments, where the figure reported is the change in the finished garment. Specify the number of cycles, not only the method: a fabric that passes one cycle and fails five is a common and expensive late discovery.

Report warp and weft separately: a single figure hides the direction that actually fails, and for most garments that direction is the warp — the length the cutter relies on for panel dimension. On stretch wovens, shrinkage and stretch recovery must be read together, because a fabric that grows in the wash and then relaxes can pass both tests and still measure wrong on the cutting table.

Abrasion, Pilling and Snagging: Surface Life

Martindale abrasion (ASTM D4966, ISO 12947) reports the number of rubs a fabric survives before a defined end point — two broken threads, or a stated change in appearance. Test pressure matters, so 9 kPa and 12 kPa results should not be quoted side by side. Pilling is graded on a five-step scale. For workwear and pack-contact panels, abrasion and pilling belong in the specification alongside yarn and construction.

The failure seen in the field is rarely a hole: it is a dulled, fuzzy surface at cuffs, elbows and pocket edges, which is why the appearance-based end point is often the more useful one to specify.

Water Resistance: Hydrostatic Head, Spray Rating and Repellency

Two very different claims hide behind the word waterproof. Hydrostatic head (AATCC 127, ISO 811, or ASTM D751 for coated and laminated goods) measures the pressure at which water penetrates the fabric, reported as a column of water in centimetres or millimetres. Spray rating (AATCC 22, ISO 4920) measures how effectively the surface sheds water, on a 0–100 scale. A fabric can hold a high hydrostatic head and still wet out on its surface.

Outdoor programmes should specify both figures, plus the number of home launderings the repellency must survive before re-treatment. Read the standard name carefully: AATCC 127 and ISO 811 apply different rates of pressure rise, and coated constructions are commonly tested under ASTM D751. A 5,000 mm result from one method is not automatically a 5,000 mm result from another.

Side by Side: Tests, Methods and the Failure You Will See

AATCC, ISO or ASTM? Reading the Standard Code

AATCC methods dominate US retail and brand requirement lists; ISO methods dominate European and many Asian buyers; ASTM is common where coated performance fabrics are involved. The three overlap but are not interchangeable, so the same fabric reported under two systems will not give identical numbers. Always state the standard, the option inside it, and the acceptance level.

How to Write a Spec the Mill Can Actually Meet

1. Name the method and the option. A standard number alone is ambiguous; the option defines exposure and end point.
2. State the level and the direction. Report warp and weft, dry and wet, acid and alkaline separately.
3. Say when the report is due. Lab dip, bulk sample and production roll are three separate deadlines.
4. Define the consequence of failure. Whether a marginal result triggers re-test, re-dye or rejection should be agreed before bulk.
5. Test the garment, not only the fabric. Seam slippage and garment shrinkage behave differently from flat-goods results.

Combined with the construction spec — yarn, count, weight, weave — these five points turn a wish list into a measurable order. Our polyester woven buyer's guide covers how that package sits alongside sampling and supplier audit.

Common Buyer Traps

Trap 1: Quoting a lab-dip report against bulk. A hand-dye lab dip is not a claim about a production lot. Always ask which specimen the number refers to.

Trap 2: Specifying a grade without a method. "Wash fastness 4" cannot be enforced. "AATCC 61 2A, colour change 4 minimum, staining 3–4 minimum" is a testable clause.

Trap 3: Reading only the colour-change column. Multi-component garments most often fail at the staining column — the trim or lining that picked colour up from the shell.

Where Six Dragon Textile Fits

We weave polyester and nylon wovens for apparel — dyed and printed, plain and stretch, with finishes such as water repellency and coating. Dyeing, printing and finishing run through long-term partner mills, and test reports are issued per method and per stage on request. Exact performance levels depend on the construction and finish agreed for each order, so we confirm them against your specification rather than quoting a blanket figure. On the print route, see digital, screen and sublimation printing on polyester woven; on the fibre decision, see polyester versus nylon.

Send the end use, target weight and the standards you need reported, and we will come back with the construction and the data behind it: send your requirement.

Pro FAQ

Which test should I specify first?

Start from the failure your end use will actually meet: wash fastness and shrinkage for everyday apparel, light fastness for sun-exposed styles, abrasion for workwear, hydrostatic head for rain protection. Specifying everything at maximum level raises cost without reducing the risk that matters.

Why do two labs give different results on the same fabric?

Different methods, different options within a method, different specimen preparation and different operators. Agree the method, the option and a single reference lab before bulk, then compare like with like.

Is a grade of 4 on the grey scale good?

For most apparel programmes a 4 is solid and 4–5 is stronger, but the number only has meaning next to a method and a threshold. A 4 under a mild wash procedure is not comparable to a 4 under an aggressive one.

A test report only protects a programme when it is attached to a written specification. Fix the method, the option, the acceptance level and the specimen before bulk, then send us the details and we will quote the construction with the matching test data.