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Sourcing Decisions · 2026.10.11 · 12 min read

Fabric Weight, Composition and Colour:
Writing Enforceable Spec Clauses

"This shipment is not the same as the sample" is the most common dispute in sourcing, and in most cases the root cause is not a dishonest factory — it is a specification that only ever existed verbally. An enforceable spec needs four things: the item, the value, the tolerance and the test method. This article gives you a ready-to-use spec table, the six items most often left out, and clause wording you can lift straight into a contract.

The most practical sentence first: in a textile dispute, a verbal description like "260 gsm, 95% cotton" is almost useless. "260" can mean 258 or 275; whether one percentage point of cotton matters is undefined; and if shade is judged by eye, the two sides will never agree. An enforceable specification consists of four elements: item, value, tolerance and test method (including sampling).

1. A ready-to-use specification table

The table below covers the items common in womenswear sourcing. Values and tolerances reflect conventional industry ranges — confirm against your category, target-market regulation and testing laboratory.

ItemExample wordingCommon toleranceTest method (example)
Fibre composition95% cotton / 5% elastane (all components stated)±3% per component (or as agreed)GB/T 2910, ISO 1833
Mass per unit area (weight)260 g/m² (woven); knits stated as g/m²±5%GB/T 4669, ISO 3801, ASTM D3776
Width150 cm usable (distinguish full from usable width)±2% (common)GB/T 4666
Thread density133 × 72 per inch±2%GB/T 4668
Shrinkage (dimensional change)After washing: ≤3% warp and ≤3% weftAs agreed (often ≤3% or ≤5%)GB/T 8628, GB/T 8629, ISO 6330
Colour fastnessRubbing ≥ grade 4; washing ≥ grade 4; light ≥ grade 4≥ grade 4 (common)GB/T 3920 / 3921 / 8427, ISO 105
Shade≥ grade 4 against the approved swatch; lot-to-lot ≥ grade 4≥ grade 4Grey scale per GB/T 250
Pilling≥ grade 3–4≥ grade 3 (common)GB/T 4802.1, ISO 12945
SafetyMeets target-market basic safety requirements—GB 18401 (China), destination regulation
Unit conversion is where most errors happen. Denim is often quoted in ounces: 1 oz/yd² ≈ 33.9 g/m², so "10 oz denim" is roughly 339 g/m². Knit weights are commonly given in g/m² but English-language markets also use oz/yd² — without conversion, an entire lot can come out a grade thick or thin. Write everything in g/m² in the contract and state the conversion.

2. Six items most often left out

  1. "Cotton" with no ratio. "Pure cotton" and "95% cotton / 5% elastane" are different fabrics — stretch, shrinkage and hand-feel all differ. State every fibre's share.
  2. "A bit thicker" with no weight. Hand-feel descriptions cannot be inspected. Weight is the only figure an instrument can measure.
  3. No tolerance. Without one, "2 g off" or "1% off composition" can be argued either way — depending on who is talking.
  4. No test method. The same sample tested to different standards, or sampled at different points, can differ by a grade. "Tested per GB/T 3920" gives you a shared language.
  5. No dye-lot clause. This is the origin of "same style, different colour". Specify that the whole shipment uses one dye lot, or that any lot change requires buyer approval.
  6. No shrinkage figure. Excess shrinkage makes garments change size after washing and can trigger a full return. It must be agreed at the fabric stage, not discovered before shipment.

3. Making a spec stick: sealing, testing, inspecting

  1. Seal and sign a swatch. Each side keeps a signed, sealed dye-lot swatch of the approved fabric as the sole reference for bulk comparison. Shade is judged against it, not from memory.
  2. Request test reports. For key items — composition, weight, fastness, shrinkage — ask for third-party (such as SGS, BV, Intertek) or in-house reports stating method and date.
  3. Inspect the bulk. Re-test key items by lot or batch, covering at minimum composition, weight, shade and shrinkage. Inspection before shipment is what leaves room to fix things.

4. Clause wording you can lift directly

The block below can be adapted to your category and placed in the order confirmation or purchase contract:

Fabric Specification Clause (sample)
The fabric delivered shall conform to the following specification, with the signed and sealed dye-lot swatch as the reference for shade:
(1) Fibre composition: 95% cotton / 5% elastane, each component within ±3% (tested per GB/T 2910);
(2) Mass per unit area: 260 g/m², within ±5% (tested per GB/T 4669 / ISO 3801);
(3) Usable width: 150 cm, within ±2%;
(4) Dimensional change after washing: no more than 3% warp and weft (tested per GB/T 8629 / ISO 6330);
(5) Colour fastness: rubbing and washing not below grade 4 (tested per GB/T 3920 / GB/T 3921);
(6) Shade: not below grade 4 against the sealed dye-lot swatch; the same dye lot to be used for the whole shipment, and any lot change subject to the buyer's written approval;
(7) Test reports for the above items to accompany delivery; the buyer may re-test by lot before shipment. Non-conforming goods may be rejected or reworked at the seller's cost.
Where LIUYU sits: a womenswear development and production factory in Guangzhou, with an in-house pattern room and a production team of 80+, having served 307 clients across 59 countries. We align the fabric specification with you at the sampling stage — composition, weight, width, shrinkage, fastness and shade stated item by item with values, tolerances and test methods, and one sealed swatch kept by each side; from about 50 pieces per style, first samples in about 3–5 days and bulk in about 10–20 days. Settle the spec first and "this is not the same as the sample" never arises.

A spec clause is not a matter of trust — it is a matter of replacing "how it feels" with "what can be measured". Item, value, tolerance, test method: write all four and acceptance has a basis, and the relationship is far less likely to end badly.

Frequently asked

Why is "260 gsm, 95% cotton" in a contract not enough?
Because tolerance and test method are missing. "260" yields different results under different standards and at different sampling points, and whether one or two percentage points of composition is acceptable must be agreed in advance. "260 g/m², ±5%, tested per GB/T 4669" is the enforceable version.
What tolerance is normal for fabric weight?
±5% is the conventional industry practice, varying by fabric type and agreement. Knits and denim usually allow more, worsted qualities less. What matters is putting it in the contract rather than arguing later — with no tolerance stated, ±1% and ±10% can both be called conforming.
How should shade be specified?
Two things: a reference and a range. The reference is the signed and sealed dye-lot swatch, with shade not below grey-scale grade 4; the range is the clause that the whole shipment uses one dye lot, and any lot change requires the buyer's written approval. "Close in colour" cannot be inspected.
Why put shrinkage in the fabric clause instead of testing it at the garment stage?
Because shrinkage is a fabric property and cannot be corrected later. Excess shrinkage makes garments change size after washing and can trigger a full return. A common requirement is no more than 3% warp and weft after washing (or 5% by category), tested per GB/T 8629 at the fabric stage.
What must a complete fabric specification clause contain?
All four elements: item (composition, weight, width, shrinkage, fastness, shade and so on), value, tolerance, and test method with sampling. Add sealed swatches, accompanying test reports and the right to inspect before shipment. That gives acceptance a shared basis and any dispute a standard to be judged by.