Canvas / Duck Cloth
bags, upholstery, workwear, tents, aprons, boat sails
Canvas and duck cloth are both heavy plain-weave cottons, and the terms overlap in everyday use. Technically, duck is woven tighter and denser than canvas, using two yarns twisted together in the weft, which makes it more tightly packed and slightly more water-resistant for a given weight. Both are graded by ounces per yard in the US (roughly 7 to 18 oz), translating to a wide range of 270 to 600 g/m².
The weight and tight plain weave give canvas and duck their main property: they hold shape without any interfacing. There's no drape to speak of. It doesn't fray much, which makes raw edges usable on bags and aprons, and it stands up to heavy topstitching and repeated abrasion. It's stiff to sew through at heavier weights and can be hard on home machine needles and motors past about 12 oz.
This is the fabric for tote bags, aprons, workwear, upholstery, and outdoor gear like tents and sails, anywhere structure and abrasion resistance matter more than hand-feel. Lighter-weight canvas (around 7-10 oz) is workable for structured garments like jackets; heavier weights are closer to a hardware-store material than an apparel one.