Canvas stretching tools (canvas pliers) are pinching tools used when preparing a stretched canvas as a medium, particularly for oil painting.

When stretching the canvas (painting surface) onto the wooden frame, attach the canvas using tacks (canvas tacks) while stretching the canvas to an appropriate width using equal strength in each direction. A canvas stretching tool, a plier whose ends flair out widely to the sides, is necessary at this stage. These tools are made of metals such as forged steel or aluminum alloy; they often have a spring between the two handles such that at rest the pliers remain open. The width of the ends, which is what clasps the canvas, ranges from 4.5cm for small tools to 12cm for large ones. These large tools are appropriate for stretching large-size canvases of size 100 and above. The inner sides of the clasping surfaces either have rows of “teeth” or are made of polyurethane rubber, both of which allow the tool to firmly grasp the canvas. Also, at the base of the clasping portion there is a protuberance that one can use against the wood frame as a fulcrum, taking advantage of the resulting lever to making the pulling movement easier and allowing one to pull the canvas tight.

Should the polyurethane on the clasping surface of the stretching tool wear down, it can be replaced by crimping a new rubber surface on after removing the old surface completely with a flat-blade screwdriver and then applying rubber/metal instant glue to the surface of the tool.

Canvas stretching tools and replacement polyurethane rubber surfaces are available at most art supply stores.