Material selection

Cotton canvas shrinkage: agree the size before and after washing

25 Oct 2026

Answer first: agree whether the dimension on the drawing is measured before or after washing, and write it on the spec sheet. Cotton canvas moves when it is wet, so a bag cut from unwashed fabric reaches the customer a different size from the one that was approved — and nobody notices until the first customer washes it.

Why the number moves

Cotton is woven under tension and relaxes with water and heat. A panel cut from the roll and sewn straight away carries that tension into the finished bag; the first wash releases it. The sample you approve is therefore not the size your customer receives, unless somebody decided which of the two sizes the drawing describes.

What shrinks and what does not

• Canvas moves. This is the material behaving normally, not a defect.
• Zip tape does not. Sew a zip into a panel that later shrinks and the zip ripples along the opening.
• Webbing moves a little. A handle cut to an exact length is a different length after the first wash, which is why the ends are bar-tacked rather than only stitched.
• Print does not follow the fabric. A printed panel that shrinks pulls away from its own artwork, so registration drifts where the print crosses a seam.
• Linings move at a different rate. A cotton shell with a synthetic lining puckers after washing unless the lining is cut to allow for it.

Where it actually bites

Not on a tote, where a centimetre is invisible. It bites on anything fitted: a sleeve built to a device dimension, a pouch built to a bottle, a case whose foam insert has to line up with the divider. Those are the products where an unwashed measurement becomes a return.

How to close it out

• Name the measurement. “30 cm after washing” or “30 cm as cut” — one of the two, on the drawing.
• Test it on the sample. Wash the approved sample once, let it dry flat, measure it again, and record the difference for that specific fabric.
• Take the fabric’s own figure. Ask for the washed and unwashed measurements of the fabric you are ordering, not a general percentage for “cotton”.
• Use a material that does not move where the fit is tight — polyester canvas, 600D is dimensionally stable where cotton canvas, 16 oz is not.

Two notes on the material family

Cotton canvas, 10 oz is the light one: it moves less in absolute terms but creases more. Waxed canvas, 16 oz is a different case again — the wax finish marks with use and creases at the fold, and on a waxed bag that is the material, not a fault. Say so on the retail page before the customer decides it is one, as we do on the waxed canvas shopper.

Where to put it in the brief

One line in the spec: fabric, colour, and whether dimensions are washed or as-cut. Sampling runs about 7 working days per round, which is enough time to wash and re-measure one sample. Orders start at 3,000 pcs, or 1,000 pcs per colour or size on stocked materials. Send the drawing with the wash note and we will confirm the size on the sample.