Garment Testing for Tech Packs: 5 Tests to Require

Your first bulk order arrives. The tees are a size smaller after one wash, the black bled onto the white trim, and the seams on the leggings are already gapping. The factory says the fabric was “as approved.” If your tech pack never asked for testing, they’re probably right.

Factories don’t run quality tests by default. They run the ones you put in writing, which is why garment testing for tech packs is so important. Here are the five that catch the most problems, how the factory actually does each one, and what to write in your tech pack.

1. Shrinkage

How the factory tests it: they mark a fabric sample at set distances, wash and dry it under set conditions, then measure how much the length and width changed. The result is a percentage.

Standard to name: AATCC 135 for fabric, or AATCC 150 for a finished garment.

Shrinkage is the one that hurts founders most, especially on cotton knits. It also affects your pattern. If the fabric shrinks, the pattern needs room built in, and that applies to every size you grade.

In your tech pack, write the method, the wash and dry conditions (match them to your care label), and the maximum shrinkage you’ll accept for length and width. A common starting point: 3% max for wovens and 5% max for knits, after 3 washes.

2. Colorfastness

How the factory tests it: they wash the fabric next to a strip of white test fabric, then rub it with dry and wet white cloth. Fading and color transfer are graded on a 1 to 5 scale, where 5 means no change.

Standards to name: AATCC 61 for washing, AATCC 8 for crocking (rubbing).

Dark colors and deep dyes are the usual problem. If color rubs off in the test, it will rub off on your customer’s couch, their white sneakers, or the rest of their laundry.

Write the minimum grade you’ll accept for each test. Activewear and swim may need extra tests for sweat or chlorine, so think about how the product actually gets used.

3. Pilling

How the factory tests it: they tumble or rub the fabric for a set number of cycles, then grade the surface against reference photos on a 1 to 5 scale.

Standards to name: ASTM D3512 (random tumble) or ASTM D4970 (Martindale).

Pilling is what makes a sweater look old in a month. Knits, fleece and synthetic blends show it fastest. Include the number of cycles in your spec, not just the grade. A good result after a short test and a good result after a long one are not the same claim.

4. Seam strength

How the factory tests it: they clamp a sewn seam in a tensile tester and pull until it slips or breaks, then record the force it took.

Standard to name: ASTM D1683.

If seams fail, the fix is usually construction: stitch type, stitch density, seam allowance or thread. Not just stronger thread. This matters most on fitted garments, stretch fabrics and anything that takes stress at the crotch, shoulders or side seams.

5. Fit on a body

How it’s checked: a sample is sewn in your base size, tried on a fit model, and measured at every point against your spec sheet.

Standard to name: there’s no lab test for this one. The standard is your own measurement spec.

Flat measurements can look right and still hang wrong. A fit sample on a real body shows pulling, twisting and gaping that a tape measure on a table won’t.

Where these garment tests go in the tech pack?

If you are starting small with a low MOQ, I suggest putting this into your BOM page.

If you are ordering several thousand units, give testing its own page, not a line buried in the notes.

A simple table works:

• Test name

• Method (the AATCC or ASTM number)

• Pass requirement

• Which fabric or component it applies to

• When it’s tested: fabric stage, pre-production, or final product

Include trims too. Elastic, zippers and prints can fail separately from the main fabric.

Then ask for the results in writing. A verbal “yes, we tested it” doesn’t count.

FAQ

Who pays for testing?It depends on your agreement. Mills often have test reports for their fabric already, so ask for those first. For anything meant for kids, I recommend independent testing.

Do I need every test for every product?No. A cotton tee needs shrinkage and colorfastness at minimum. Leggings need seam strength and pilling too. Pick based on the fabric and how the product gets worn and washed.

What if a test fails?Decide before production. Options include a different fabric, a pre-wash, a pattern adjustment for shrinkage, or a construction change. Put the remedy in your agreement so it isn’t a surprise.

Want help adding testing specs to your tech pack? Book a free 15-minute intro call at tmtechpacks.com/introcall.

More info on fabric selection: https://www.tmtechpacks.com/post/gsm-is-not-a-quality-rating-what-fashion-founders-get-wrong-about-fabric-weight

Other common mistakes startup founders make: https://www.tmtechpacks.com/post/fashion-tech-pack-mistakes