Canvas comes in many forms, canvas pads, canvas panels, boxed canvas and canvas rolls. Canvas is made up of either cotton or linen, linen being a more expensive material and in some cases the preferred material. Canvas makes an excellent surfaces for acrylics and oil. Most canvas products are primed and ready to paint when presented in a ready made box or panel as they have already been stretched. Canvas on a roll tends to be un-primed to allowed for better stretching prior to fitting to your chosen surface.