Cris asked me to show how I stretch my own canvas so here's my try. First buy four stretchers. Two in one size and two in another (unless you want a square canvas). I think mine are 16" x 20". Stretchers are pretty cheap. Or you can make your own which is another ball of wax.
This and the next photo I got reversed. You have a sort of dove tailed corner on each stretcher. Fit these together at each corner to form a rectangular frame. This is the corner fitted together.
Here is the corner before fitting them together. Actually I often use a hammer to lightly tape them into place.
Take your roll of canvas, either cotton duck or linen (I wish) and unroll it a bit.
Set your frame on top of the canvas. You will want to cut a piece big enough to go over the frame's edge so you can staple it to the frame on the back. I figured I needed a two inch border on all sides, which equals four inches per side. I measured this and then cut a slit and then tore the canvas to make the edge.
You will need a staple gun. Preferably a newer one than this. Mine is over 30 years old and doesn't work right and hurts my hand. So why don't I spend $16 to buy a new one? Hmm.
You place one staple on each side of the canvas. This holds the canvas in place for you to staple some more. You always just do a few staples on one side, then go to the opposite side and do a few more. All around the canvas.
Stapling step two. Two more staples are added at intervals. Before stapling you want to pull the canvas lightly to create tension and stretch. Go all around the stretcher stapling in this manner until all is done except the corner. Just as Jane says in the following video my staples don't always go in all the way so I tap them in with the hammer.
No way I can show you how to do the corner step by step via photos. I probably don't do the corners very well myself. However the next post is a video of Jane showing how to stretch a canvas and she shows the corners well.
Canvas completely stretched.
Now you want to gesso the canvas. I used acrylic gesso even when I used to paint in oils. However, there may be some other kind of gesso to use for oils, I don't know.
I use a cheap brush to apply the gesso.
Here half the canvas has gesso, half does not just to show you the difference in color. Let the gesso coat dry then apply as many more coats as you want. The more coats the smoother the surface will be. You might want to sand the surface lightly between coats. There you have it. I think it is quite satisfying to make my own canvas. Also, if you want really large canvases I think this is the only way to do it. Or canvases not of the dimensions of ready made style canvases.
Usually once gessoed the canvas will have more tension and shrink a little. It should sound like a drum when tapped with the fingers. Also if you do a painting and don't like it, you can of course paint over it, or remove it from the stretchers and use the stretchers again.
What follows is a video I found on You Tube of Jane stretching a canvas. In previous videos she has demonstrate making your own stretchers. So the beginning of this video is about finishing off the wood with a router. That is not applicable for store purchased stretchers. However, be patient as she will soon show you how to stretch the canvas. She does a very good demonstration. :)