Canvas is a heavy plain-weave fabric, usually cotton, from about 240 GSM (7 oz/yd²) for a light canvas to 600 GSM (18 oz/yd²) for the heaviest duck, and it sews well on a home machine as long as you match the needle, thread and stitch to the weight. Use a jeans needle in 100/16 or 110/18, polyester or heavy-duty thread, a 3–3.5 mm stitch and a walking foot, hold the layers with clips rather than pins, pre-wash plain cotton canvas (never waxed), and press hot with steam. The craft is in managing bulk: grade seams, level the foot at thick crossings and turn the handwheel through the worst spots.
Quick reference: how to sew canvas
| Setting | Cotton canvas and duck |
|---|---|
| Needle | Jeans/denim 100/16 for light and medium canvas (up to about 340 GSM / 10 oz); 110/18 for heavy duck |
| Thread | All-purpose polyester for light canvas; heavy-duty polyester or topstitching thread (Tex 40–60) for medium and heavy |
| Stitch length | 3 mm for seams, 3.5–4 mm for topstitching |
| Presser foot | Walking foot; a Teflon or roller foot on waxed canvas |
| Pre-wash | Plain cotton canvas: yes, it shrinks 3–8%; waxed or coated canvas: no |
| Pressing | Cotton setting with steam and a clapper; waxed canvas: low heat, no steam, press cloth |
| Seam finish | Bound, serged, flat-felled or enclosed in a lining; topstitch every seam that takes strain |
| Holding layers | Clips and weights; pins bend and leave permanent holes in waxed canvas |
What is canvas, and what do the duck numbers mean?
Canvas and duck are the same dense plain weave, usually in cotton but also linen, hemp or polyester. "Duck" is the older name, from the Dutch word for cloth, and cotton duck is sold on a numbered scale that runs backwards: the lower the number, the heavier the fabric. Number 12 duck weighs about 11.5 oz/yd² (390 GSM), number 10 about 14.7 oz (500 GSM) and number 8 about 18 oz (610 GSM). Shops that do not use the numbers list the weight directly, often in ounces per square yard (multiply by 34 for GSM).
As a rule of thumb:
- 7–10 oz (240–340 GSM): light canvas for aprons, bucket hats, lined pouches and unlined totes. A domestic machine sews this without complaint.
- 10–12 oz (340–410 GSM): medium canvas for tote bags, cushion covers and work aprons; the standard weight for bag making at home.
- 14–18 oz (475–610 GSM): heavy duck for tool rolls and bags that must stand up on their own. Sewable at home in two layers, difficult in four or more.
Waxed canvas is cotton canvas impregnated with wax so it sheds water. It is stiff, holds creases like paper, marks wherever it is pinned or folded, and the wax melts under a hot iron. Sew it dry, with clips and a Teflon foot, and let it soften with wear.
Should you pre-wash canvas?
Plain cotton canvas, yes: it shrinks 3–8% depending on how loosely it was woven and finished, and it softens, which is what you want for an apron or a bag that will go through the wash. Wash it hot, tumble dry, and press it while damp because dry canvas creases hard. Unwashed canvas stays stiffer and makes a crisper bag that you spot-clean instead; decide before you cut, because the two behave differently.
Waxed, coated and laminated canvas is never washed; wipe it with a damp cloth.
How do you cut canvas?
Canvas is stable and easy to cut on grain, but it is thick. Cut it in a single layer rather than folded: a double layer of 12 oz duck is too much for most rotary blades and the under layer shifts. Lay the pieces out with pattern weights, trace with chalk, and cut with a 60 mm rotary cutter or heavy shears; a 45 mm blade dulls after one bag. The pins, clips and weights comparison explains why weights win on heavy fabric.
Large rectangles, such as bag bodies, pockets and apron bibs, are quicker to measure with a ruler and chalk than to cut around a paper piece. Sewly's printed patterns treat big plain rectangles the same way, giving them as cutting dimensions instead of printed pages.
How do you sew canvas on a home machine?
Most domestic machines sew medium canvas in two to four layers; the limits appear at corners and seam crossings in heavy duck. Work through each seam in this order:
- Needle and thread first. Fit a new 100/16 jeans needle (110/18 for heavy duck) and thread the machine with polyester thread of the right weight, the same thread in the bobbin. Test on a scrap of the full thickness and adjust the upper tension if the bobbin thread shows on top.
- Stitch length 3 mm. Canvas does not fray badly for its weight, and a longer stitch sinks into the weave instead of perforating it.
- Clip, do not pin. Pins bend in canvas and will not pass through four layers; clips hold the edge flat and come off as you reach them.
- Sew slowly and let the walking foot feed. The walking foot grips the top layer so it moves with the bottom one, which keeps the two sides of a bag the same length.
- Level the foot at crossings. When the foot reaches a seam allowance or a handle, stop with the needle down, raise the foot, slide a folded scrap behind it so it sits level, and continue. Turn the handwheel by hand through the thickest point rather than forcing the motor.
- Grade and trim. Trim one seam allowance to 6 mm (1/4 in) at every crossing and cut corners diagonally before turning. Boxed corners in a bag base are where bulk piles up; trim them to 1 cm (3/8 in) after sewing.
- Topstitch and bar-tack the strain points. Handles, pocket tops and the ends of a zip get a box of stitching or a 1 cm bar tack (a dense zigzag with a 0.5 mm stitch length); this is what holds a loaded bag together.
If the machine stalls, skips or the needle deflects, the fabric is beyond its strength: try a lighter canvas, fewer layers, or a mechanical machine with a metal frame. The post on sewing machines for denim and canvas lists the features that matter.
How do you press canvas?
With the hottest setting, steam and patience. Press seams open with the point of the iron, then flatten them with a clapper: steam, press the wooden block onto the seam and hold it until the canvas is cool. A pressed-open seam in heavy canvas is half the thickness of one pressed to the side, which matters at the next crossing. Press waxed canvas on the lowest setting through a press cloth, or skip the iron and finger-press the creases; the wax softens slightly and resets as it cools.
How do you hem canvas?
Light and medium canvas take a double-fold hem of 1.5 cm then 2.5 cm (5/8 then 1 in), topstitched. Heavy duck takes a single fold: serge or bind the raw edge, fold 2.5 cm once and topstitch, because a double fold in 18 oz canvas is a wad of fabric that no home machine enjoys. Where two hems meet at a corner, on an apron or a tote with turned-under edges, a mitered corner removes the overlapping square of fabric and lies flat.
What should you sew with canvas?
- A tote bag in 10–12 oz canvas, lined with a lighter cotton, with boxed corners and an inside pocket.
- An apron in 8–10 oz canvas or a canvas-weight linen: washable, stands up to a kitchen, and the straps and ties are straight strips.
- A zip pouch or bucket hat in a light 7–8 oz canvas, which gives structure without the thickness of duck.