Artists use a variety of surfaces for paintings such as wood, unstretched canvas, stretched canvas, glass, silk and linen. Painting on unstretched canvas is very similar to painting on stretched canvas. The main difference is that the painting surface isn't drum tight like a stretched canvas.
Primed canvas is much more convenient to purchase than to make yourself. The advantage to unprimed canvas over primed canvas is that if you change your mind and decide to stretch the canvas before painting, primed canvas is more difficult to stretch. To prime your canvas yourself, coat the canvas with rabbit skin glue and oil primer. If you paint with acrylics, use acrylic gesso to prime the canvas. Gesso primer can cause oils to flake as they age.
Setting up Canvas
Cut the canvas to the dimensions you want to paint. If you plan to mount the painting on stretcher bars, leave several extra inches around the edges for folding over the bars. There are a few ways you can set up your unstretched canvas for painting. The simplest way is to tape around the edges and affix the canvas to cardboard or wood and set it on an easel. Canvas can also be taped directly to a wall for painting.
The biggest advantage unstretched canvas has over stretched canvas is ease of transport. Unstretched canvas can simply be rolled up into a tube and carried. There are no wooden stretcher bars to haul around. Stack finished dry paintings to await framing. Carry finished paintings by rolling them paint-side out with glassine spacers between them to prevent sticking. Roll the paintings in a cushion material such as foam or bubble wrap and place the whole thing in a larger tube.
Unstretched canvases can be framed a couple of different ways. Cut the painting to the size you want, leaving 1/4-inch around the edges where the painting will be covered by the frame. Glue the cut canvas to a stiff backing. Varnish the painting and frame as normal. If you left room around the edges of the painting you can place the canvas on stretcher bars, stapling the canvas to the back of the bars. Varnish the painting and place it in a frame using wire clips.