Cotton or linen yarn is woven in a simple over-one, under-one plain weave. Duck canvas packs its threads more tightly. Cloth is sold by weight, from about 4 ounces a square yard for light to 12 for heavy.

The woven cloth is washed and pressed flat, then sealed with a size that stops later layers soaking straight through. Traditional sizing used rabbit-skin glue, and modern lines use an acrylic sealer.

Titanium dioxide for whiteness and ground calcium carbonate for tooth are stirred into an acrylic resin dispersed in water. The chalky filler gives the dried surface enough grip for paint.

Primer is spread across the cloth in two or three thin coats, each dried before the next. The coats fill the weave without hiding its texture and keep oil paint off the raw fibers, which oil would slowly rot.

Wooden bars with a slightly rounded front edge are cut and joined at the corners. Many frames have loose mitered corners with small wedges, called keys, that can be tapped in later to tighten a sagging canvas.

The primed cloth is wrapped over the frame and pulled evenly from the middle of each side outward, then stapled at the back or sides. Even tension keeps the frame from twisting and the surface drum-tight.