To stretch any piece of rolled canvas, ensure there is at least 2 to 3 inches of extra canvas on each side. If a piece of rolled canvas already has a painting on it, make sure there is at least two to three inches of extra, unpainted canvas on either side. There are two steps to framing rolled canvas. First it must be stretched over stretcher bars and then framed.
Purchase stretcher bars which come in packages of two. The stretcher bars will have different measurements on them. You want measurements that will perfectly frame your canvas. For example, if you have a painting that is 8-by-12 inches, purchase a set of bars measuring 8 inches and a set of bars measuring 12 inches.
Connect the stretcher bars by their corners by matching the grooves and sliding them together. Measure the inside of the frame from each inside corner to the opposite inside corner. Both measurements need to be exactly the same to ensure the frame is perfectly straight. If you do not have exact measurements, slightly tap the corners with a mallet until the measurements are exact.
Place the stretcher bar frame face-up over the face-up painting and line it up so that the painting shows through the frame. Hold the frame down and flip up each corner of the painting over the outside corner of the stretcher bars. Mark the back of the painting at each outside corner. These marks will help you line up the painting when stretching the canvas.
Flip the painting over so it is facing down and line up the frame so that each outer corner is lined up with the marks you made in the previous step. You want the back side of the stretcher bars to be facing upwards.
Pull the canvas over one of the longer sides of the stretcher bar frame, ensuring you don't move the rest of the canvas. Staple the canvas to the back of the stretcher bar, at the center. Leave a little room between the bar and the staple so that if you make a mistake, you may remove the staple easily. Repeat this method for your first four staples.
Continue on the opposite side of the first staple. Pull the canvas tightly until you see a bit of wrinkling from the first staple where you are pulling from. Staple this securely to the stretcher bar.
Pull the canvas over the stretcher bar tightly on the remaining two sides and staple the canvas with one staple on each side.
Flip over the frame and look at the canvas to see if it's pulled tightly enough. If not, remove the necessary staples by prying them out with a flat-head screwdriver and fix your mistakes.
Staple two more staples on every side of the frame, so that you end up with three staples near each center on each side of the frame.
Pull the extra canvas around the corners by square-folding one of the sides of the corners in. Fold the excess canvas material under itself and fold the other side of the corner over the excess canvas material. Pull this side tightly to hold everything together and create a neat corner. Staple the corner down. Repeat will all four corners.
Continue stapling along the back of each stretcher bar from the center until you hit the corners. Leave a bit of room between the staples to ensure the canvas doesn't tear.
Purchase a frame with a removable glass front that is the size of your painting. For example, for an 8-by-12 painting, purchase an 8-by-12 frame. Use canvas hanging hardware like offset clips to attach the painting to the frame. These clips are available at craft or frame supply stores. Some clips need to be screwed in while others don't, so follow the instructions that came with the ones you have.
After wrapping the canvas, protect it with a sealant spray to keep the colors intact and the dust off.
This method should only be done with smaller paintings. If the painting is rather large, take it to a professional.