Four checks to run on fabric before you accept it

Why check the roll at all, if the swatch was approved?

Because the swatch and the roll are two different purchases, and only one of them was made in front of you.

A swatch is selected. A roll is produced, to an order, sometimes months later, sometimes by a mill substituting a yarn it had. Everything between those two points is where a specification quietly drifts: a blend that is not quite the blend, a dye lot that reads differently outside, a weight that came in short.

None of the four checks below needs equipment beyond a set of scales, and all four can be done in the time it takes to unpack a box. They are worth running on the roll, not on the sample, because the roll is what your customer will be wearing.

How do I know the fabric is the fibre it says?

Pull a thread from the edge and put a flame to it, over a sink or a metal tray.

Cotton and other cellulose fibres burn to a soft ash that crumbles between your fingers, and smell like burning paper. Polyester and nylon melt: the flame produces a hard bead at the tip that cools into a small plastic lump you cannot crush.

That bead is the whole test. If you ordered 100% cotton and you get a bead, there is synthetic in the yarn. A blend will do both at once, ashing and beading together, which is itself informative when the invoice said one fibre.

This matters beyond the principle. Blend content changes how a garment shrinks, how it takes dye, how it feels after twenty washes, and what you are legally required to put on the care label. A fibre content that is wrong on the roll is wrong on every label you print.

Why does my fabric look a different colour in daylight?

Carry the roll to a window or a doorway and look at it in daylight, against the swatch you approved.

Two fabrics can match perfectly under the shop lights and separate the moment they reach the sun. That effect happens when the approved colour and the delivered colour were reached with different dye recipes: the eye reads them as identical under one light source and as clearly different under another.

It is not a defect in the sense that anyone did it wrong. It is a mismatch that only exists under certain light, and the light your customer stands in is not the light your factory does.

Check it against the physical swatch, not against a photograph or a screen, and check it in the same daylight rather than one in the morning and one at dusk. A colour that changes when you carry it outside is a colour you never actually approved.

How do I test whether the dye will rub off?

Dampen a piece of white cotton, press it firmly against the fabric, and rub in a small circle a dozen times.

Whatever transfers to the white cloth will transfer to something your customer owns. On a dark denim that is a familiar and sometimes intended characteristic. On a black t-shirt against a pale sofa, or a red lining against a white shirt, it is a complaint and a return.

This is dye that never fixed to the fibre, usually because the wash-off after dyeing was cut short. It is one of the cheapest faults to find and one of the most expensive to discover after delivery, because it does not show up until the garment has been worn.

Run it wet rather than dry. Dry rubbing is a gentler test and will pass fabric that fails the wet one, and it is the wet one that matches how the garment gets used.

How do I check the gsm I actually paid for?

Cut a square 10 cm by 10 cm, weigh it in grams, and multiply by 100. That is your fabric weight in grams per square metre.

The arithmetic is simple because 10 by 10 centimetres is exactly one hundredth of a square metre. A cutting die makes it more accurate, but a careful square and a kitchen scale will find the fault you are looking for.

Here is the fault. The invoice says 380 gsm. The scale says 340. That is a shortfall of about a tenth, on what is usually the single largest line in your costing, and you have already paid for it.

Fabric weight is what you are buying when you buy fabric. Everything else about the cloth is a description; the weight is the quantity. A garment made at 340 when the specification said 380 is a thinner garment, it drapes differently, it will feel cheaper in the hand, and none of that is visible in a photograph or obvious from a swatch you never weighed.

Weigh more than one square, from more than one place along the roll. A single reading catches a big miss; three readings catch a roll that is on specification at the start and drifting.

What do I do when a check fails?

Go back to the factory with the measurement and ask for a price adjustment.

Not a rejection, not a dispute, at least not first. A weight that came in ten percent under is a quantity discrepancy and it has a number attached to it, which makes it the easiest kind of conversation to have. You paid for 380 and received 340; the difference is arithmetic.

Say what you measured, how you measured it, and where on the roll. A factory with a mill behind it can take that straight back up the chain, because the mill is where the discrepancy came from and the mill is the one holding the record of what it produced.

The reason to run all four on every delivery is not suspicion. It is that a brand which measures gets a different quality of attention than one which does not, and everybody in the supply chain knows within one order which kind you are.