Weight in Knitted fabric: Range, Tolerance and How to Test It

There is a version of weight in the quotation and a different one in the goods. The gap between them is a tolerance, and it is where the money is.

What weight actually controls in knitted fabric

Apparel hand and opacity. Tolerance of +/- 5 % is normal, +/- 10 % is a claim waiting to happen.

That makes it a design decision rather than a purchasing one, which is why changing it after the product is fixed costs more than changing the material.

For Knitted fabric, the working range is 120-320 gsm. Inside that band the choice is commercial; outside it, the product changes category and so does the price.

What 120-320 gsm does not tell you

Specifying the ceiling is only justified when the end product carries a warranty that would be expensive to honour. Otherwise it is cost without a customer-visible benefit.

The figure that decides the outcome is not weight itself but the tolerance around it. A supplier who quotes 120-320 gsm without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.

How to measure weight

The reference method here is Pilling, run to ISO 12945-2, with an acceptance of >= grade 3-4 at 2000 rubs. The method is the easy part; sampling and conditioning are where reports diverge.

Take samples from the beginning, middle and end of the run. A single sample from the top of a roll tells you about the top of that roll, and weight varies more across a run than most buyers expect.

Record the measured value rather than pass or fail. A marginal pass on weight tells you the process is running at the edge, which is the information you need before the next lot rather than after it.

Weight does not stand alone

Weight moves with stitch length (2.6-3.4 mm) and with courses and wales (18-32 cpi / 14-24 wpi). Tightening one usually costs money in another, and a supplier who accepts every tolerance without comment has either not understood the interaction or is planning to substitute.

This is why a specification written as a list of independent tolerances is weaker than one written as a construction. The list lets a supplier satisfy each line while missing the product.

The clause to write for weight

The line below is the version we can quote against without inventing anything. Weight appears with a tolerance and a test, not as a standalone number.

Single jersey, 100 % combed cotton, 180 gsm +/- 5 %, open width 175 cm, stitch length 2.9 mm, shrinkage <= 5 % after 3 washes, skew <= 5 %, reactive dyed, Pantone 19-1664 TCX

A specification without a test method is a preference. It becomes a requirement when the method and the acceptance value are both named, because then a substitution is visible.

When weight goes wrong

Barre (fabric bars). Horizontal bands appear after dyeing, worst on dark shades.

The cause is usually yarn count variation or uneven tension across the beam.

The test that catches it: Visual inspection on a light box after dyeing; count bands per 10 m.

What to specify instead: Yarn lot control and tension monitoring; reject at greige if bands are visible before dyeing.

None of this is visible in a quotation. It becomes visible in a retained sample and a lot record, which is why the paperwork matters more than the price on this parameter.

Four questions about weight, before you order

1. What tolerance do you hold on weight, and what did your last three lots measure against it?
2. Which method do you use for pilling, and which laboratory signs the report?
3. When weight falls outside 120-320 gsm, do you rework, downgrade, or ship and hope?
4. Which of stitch length or courses and wales would you move first to hit a lower price?

The answers are more useful than a certificate, because they show whether the process is controlled or merely inspected. Full ranges for knitted fabric are on the product page, and the measurement regime is described on the quality control page.

Failure modes worth a clause in the purchase order

Claims rarely come from a batch that was obviously wrong. They come from a structure figure that sat inside the quoted band and outside what the product needed.

The other two, with acceptance numbers attached, are in the full failure analysis for knitted fabric. A supplier who cannot name the mode he sees most often is describing a catalogue, not a process.

Seven lines that turn a quotation into a specification

Most post-delivery arguments are not about quality. They are about a document that never said which figure would be measured, on which instrument, at whose cost.

1. Composition (100 % cotton / CVC / TC / 100 % polyester): state where in the band this order sits. The middle of the band is not what a tolerance is for.
2. Weight: the figure you will accept inside the 120-320 gsm band, the tolerance on it, and the method used to measure it.
3. Stitch length (2.6-3.4 mm): name the number, not the word. If the answer only repeats the band, ask which point inside it is being offered for this order.
4. Courses and wales: 18-32 cpi / 14-24 wpi is the market band. Fix the figure you will test at goods-in, and the instrument you will test it with.
5. Deviation rule: anything outside the agreed bands is reported before shipment, not after arrival.
6. Packing and marking: shipping mark, roll or carton count and the tolerance on quantity, since a short shipment is a claim too.
7. Who inspects: third-party, in-house or none, decided in advance, with the AQL level written down.

Related reading

• Baby and children’s products
• How to Test Knitted Fabric Before You Commit to a Container
• Knitted fabric