Professionally stretched canvas can get rather costly. Fortunately, it is relatively easy to stretch canvas in the studio, especially with an assistant. It may take a few trial runs to learn how to do it properly, but once an artist is comfortable stretching his or her own canvas, it will seem well worth the effort. In addition to saving money by stretching canvas personally, artists will also be able to have better control over canvas sizes, allowing them to create custom pieces.
To stretch canvas, several tools are needed. Start with the stretcher bars or frame over which the canvas will be stretched. If the canvas is going to be large, supporting cross braces will also be needed. The next important ingredient is the canvas itself. Many art supply stores sell rolls of canvas, which should be unprimed for stretching. To secure the canvas, you will require a hammer with carpet tacks, or a staple gun. Finally, a set of canvas pliers greatly helps to stretch canvas, although they are not strictly necessary.
Once all the tools to stretch canvas have been assembled in a clean, dry place, start by assembling the stretcher bars. Make sure that they are snugly connected and square before nailing or stapling them together. You can use a grid or t-square to make sure that the stretchers are square, or you can measure across the diagonals of the canvas to see if the distances are the same. Once you are confident that the stretchers are square, roll out the canvas and cut out a square which is larger than the stretcher bars. The canvas will have to wrap partway around the stretchers, so be generous with your cuts.
When you stretch canvas, you start from the middle and work your way in, always working on opposite sides. Staple or nail the canvas to the middle of one of the supports, and then move to the opposite side, stretching the canvas as taut as you can get it. Canvas pliers will help you grip the canvas without hurting your hands, and an assistant can hold the stretcher bars and canvas to help you stretch canvas tightly across the frame. Move to the middle of one of the sides and repeat the process to stretch canvas. Then, start working your way along the edges of the supports. When you reach the corners, fold them over neatly and tack them down.
After you have stretched the canvas, you can prime it or leave it unprimed, depending on personal taste. You can either stretch canvas for each individual piece one at a time, or you can devote a day to stretching canvas so that you can stockpile a range of canvases to work with. Either way, keep the materials in a cool, dry place, and do not expose them to moisture or excessive heat. Storing the canvas flat will also help to prevent warping.