Unstretched Canvas (aka Cotton duck or Duck Canvas) is a heavy woven cotton fabric. Duck canvas is more tightly woven than plain canvas. Artists will typically stretch the fabric over a wooden frame as a surface to paint on.

Duck Canvas  has a number system used commercially to describe the weight of the canvas, but the weight and # are not one and the same (ex. 10 duck is 14.75 oz/sq yd or 500 gsm while a 12 duck is 11.5 oz/sq yd or 390 gsm. Typically for a canvas 3x4' we recommend a 11.5oz or heavier canvas. Please note that primed canvas weight refers to the weight of canvas after priming and not before, so a 17oz primed canvas is infact a 11.5oz canvas that has been double primed. For floor cloths we recommend the 15oz unprimed canvas or 17oz primed canvas.