A fabric specification for denim or shirting should state the construction, weight, width, finish, shade standard, performance test minimums, tolerances, packing and inspection method in enough detail that two mills would produce the same fabric from it. Write it as a numbered document that the mill signs and that is referenced on every purchase order. If a property is not on the specification, you have no claim when it is wrong.
Most disputes trace back to a one-line order such as "ten ounce denim, indigo, 58 inch". That line does not say whether the weight is before or after finishing, which indigo, what shrinkage is acceptable or how the rolls should be packed.
Construction and physical properties
- Fibre content and yarn type: for example 100 percent cotton, ring spun, combed or carded, open end for denim weft if accepted, and elastane percentage for stretch.
- Yarn count in warp and weft, and whether single or plied.
- Ends and picks per inch or per centimetre, with a tolerance.
- Weave: plain, twill with its direction, oxford, dobby or the denim twill angle.
- Finished weight in GSM or ounces per square yard, with a tolerance, stated as finished and relaxed.
- Finished cuttable width, with a minimum, and selvedge type.
- Finish: sanforised, mercerised, peached, enzyme washed or resin for easy care, with the finishing route named.
Performance requirements
State the test standard and the minimum for each property: dimensional change after washing under ISO 6330 or the AATCC equivalent, colourfastness to washing, rubbing and light under the ISO 105 series with the grades you need, tensile and tear strength in both directions, pilling where relevant, and skew for denim and twill shirting. For stretch denim add elongation and growth. Say which lab, or that an NABL-accredited lab is required, and whether testing is on every lot or on a sampling plan.
Set wet rubbing on dark indigo at 3 to 3.5 rather than 4, since indigo by its nature rubs off, and set light fastness according to the end use rather than copying a figure from another product.
Shade, packing and inspection
Name the shade standard, the illuminant, the Delta E tolerance and the banding rule, and say that a sealed standard will be held by you, the mill and your inspector. For packing, give the roll length range, minimum piece length, maximum joins, tube, face in or out, wrapping, label content and loose or palletised loading. For inspection, name the four-point system or the one you use, the maximum points per hundred square yards or square metres, and the sampling level.
Finally, add the commercial clauses that depend on the above: what happens if the fabric fails a test, who pays for retesting, and whether short width or weight can be settled by a rebate or must be replaced.
How we work with your specification
We turn a buyer's spec into a document the mill can sign, visit the mill to confirm it can actually meet it, and test sealed samples at an NABL-accredited lab against each line before loading. If you have a spec that keeps producing disputes, bring it to a free 20-minute sourcing review and we will mark up what is missing.