Stretching a canvas is a simple process. You just need raw canvas, stretcher bars, and a staple gun. The biggest thing to remember is to keep the canvas square to the stretcher bars and pull tight. Follow these simple steps to stretch your own canvas.
Choose Your Materials
Begin with raw, unprimed linen or cotton canvas. Linen is the more traditional painting surface, particularly for oils, but cotton is cheaper and more commonly used today. The type of canvas you use really comes down to your personal preference. You will also need to choose your stretcher bars, which will determine the size of your painting. Typically, stretcher bars are purchased in individual lengths by the inch. These will need to be fit together and attached with wood glue and a staple gun at the corners. Keep in mind that you may need cross bars to support your stretcher bar frame if you are creating a very large painting.
Measure and Cut the Canvas
Lay out the canvas under the assembled stretcher bar frame and cut the canvas to the correct size. You want the canvas to be about 2 inches wider than the stretcher bars on each side. Make a small cut with scissors into the canvas and then rip the canvas the rest of the way. Ripping the canvas instead of cutting it prevents future fraying and actually makes a straight line because it follows the fibers of the canvas.
Staple the Canvas
Center the stretcher bar frame over the canvas. On one side, pull the canvas up and over the back of the stretcher bar and secure in the middle with a staple gun. Do the same thing on the opposite side - pull the canvas tight and place one staple through the canvas and into the middle of the stretcher bar. Repeat for the other two sides. Now starting at your first staple, pull the canvas tight and staple about 3 inches to the right of the first staple. Rotate the canvas 90 degrees, pull tight, and staple again about 3 inches from the previous staple. You may want to use canvas pliers to help you get a tighter pull. The canvas should be tight like a drum. Continue this process of rotating, pulling, and stapling. As you work, you will see a diamond shape form in the canvas. This is a sign you are getting the canvas tight. As you work toward the edges, the diamond shape will disappear. When you get to the edges, fold the corners over neatly, and staple several times on the back until secure.
Prime the Canvas
Prime the surface with gesso. (You can read my step-by-step guide on how to do this here.) Gesso primes the surface by making it a uniform color, but it also helps tighten up the canvas even more. I like to use Utrecht acrylic gesso under both oil and acrylic paintings. Once you do this, your canvas is ready to paint.
Additional Tips on Stretching a Pre-Primed or Painted Canvas
To stretch a canvas that has already been primed or to stretch a painted canvas, keep in mind you will need to pull extra tight as the canvas won’t have as much “give” because of the layers of paint. You can also add canvas keys to tighten the stretcher bars if necessary. Canvas keys are oddly-shaped pointed pieces of wood that often come with your canvas or stretcher bars. Carefully hammer them into the inside corners of your stretcher bars to slightly expand the width of the bars and thus pull the canvas tighter. Also, if you are stretching a finished painting, keep checking as you stretch to make sure it remains square on the frame.