How to Stretch a Canvas

How to Get Started

Purchase a stretcher or build a frame. Canvas frames are also sometimes referred to as stretcher bars, which feature pre-cut slats that you can slip together to create the frame. This is the easiest way to customize the frame to fit your purposes and put it together quickly. Most professionals use stretcher bars. DIY frame kits like EasyWrappe are prefabricated in a variety of different sizes that will allow you to quickly fix a canvas to a frame with no outside tools, other than an X-Acto knife to trim the excess canvas. While you have to pick from a limited variety of sizes, you can stick the pre-cut wood bars to the canvas and fix them in place in less than five minutes.

Get enough canvas for the job. Get enough canvas to fit around the frame by at least six or eight inches on each side, depending on the width of the frame. It's essential that you have enough overlapping canvas to attach to the back side of the canvas, or the stretching won't work. Measure the dimensions of the frame you have, or of the eventual canvas that you want and purchase or cut a larger size of canvas, accordingly. Unprimed, sometimes referred to as “ungessoed” canvas is easier to stretch than primed or “gessoed” canvas. For the best results, buy ungessoed canvas and prime it later.

Get the other necessary materials to complete the job. You'll need a few basic tools to complete a canvas stretching job properly. Try to get the following supplies: A spray bottle filled with plain water. It’s common to dampen the back of the stretched canvas. As it dries, it will shrink and thus tighten the canvas even more. Gesso. This primer is commonly used to treat the canvas after stretching. It's a white paint mixture, made of gypsum, chalk, and other ingredients, available at most art supply stores. Specialty pliers used for canvas stretching. Available at most art supply stores, canvas pliers have flat surfaces that can be used to easily stretch canvas without pulling holes in the material. Staple gun. Regular desk staplers are not sufficient for stretching canvas. You need a heavy-duty staple gun to plant staples into wood and carpentry staples capable of gripping into the frame.

Cut your canvas. The canvas should be cut several inches wider than the dimensions of the stretcher bars, taking into account the width of each side of the frame, as well. You'll need this extra canvas to have something to get a grip on to be able to pull and stretch it. After you've got all your supplies, frame and canvas, cut the canvas to shape using a very sharp utility knife, or an X-Acto. Tearing the canvas will make a straighter line than cutting it will. Get the cut started along the appropriate line using your knife and consider tearing along the grain to make an accurate shape.

How to Stretch the Canvas

Center your frame on the canvas. Lay the canvas out flat on your work surface and center the frame on top of it. Take a minute to smooth out and clean up the canvas as much as possible before you get started. Make sure that the grain of the canvas is lined up straight with the stretcher bars on the frame. If they don't, the bars will twist and two opposite corners will lift up.

Stretch the longest sides of the canvas first. Start with the longest side of the canvas closest to you and fold it in. Insert three staples in the center of that side of the frame, along the bottom edge of the frame. In other words, you want to wrap the canvas all the way around the bar and start fixing it onto the bottom edge of the frame. The canvas around the corners should still be quite loose. You’ll tighten it up later. Rotate the canvas and frame, or move around the table to the opposite side and do the same thing. Pull the canvas tight, fold it over the frame, and insert three more staples into the stretcher bar on the opposite side. You always want to secure the canvas from the middle to the corners. Never start inserting staples close to one of the corners, or the canvas will twist slightly on the frame, making it pooch out.

Wet the canvas gently, if necessary. If you're trying to stretch an ungessoed canvas, it's common to use a spray bottle to gently dampen the canvas with some water, which will help to tighten the canvas as it dries. After you've fixed the long sides to the canvas, mist the canvas gently to promote shrinkage as you work.

Stretch the shorter sides. Go to one of the unstapled sides and give the canvas a good solid pull, fold it over, and insert two staples, attaching the canvas to the frame. Do the same thing to the other short side.

Stretch the corners. Go back to the first side you started stretching and work from your center staples out to each corner. Pull a piece of loose canvas, stretch it down, and insert a staple. Go slowly, stretching a little bit from the opposite side of the bar at a time. Continue pulling and stapling pieces of the canvas moving around the canvas edges in the same order as before. If you want, you can staple near the corners and then place a staple between the center and the corner instead. Continue until you have about four inches of unstapled space from the corners.

Fold and staple the corners. Tuck one side of the corner under the other, pulling tight, so that one straight edge is just even with the corner. Pull the corners very firmly. This is the final tightening, making it the most important. Be firm and even. Sometimes, it's helpful to make a little slit along a diagonal in the canvas, to help stretch it tight and make it flush with the sides in the corner of the frame. You want the corners to look as clean as possible, so follow the shape of the canvas and cut it if necessary.

Finish stapling the canvas. Go around the canvas and pound all your staples with a hammer to make sure everything is flush with the frame. You don’t want rough staples around the edges while you’re working. If you see a need for more staples, take a minute to fix a few more in.

How to Finish and Prime Your Canvas

Check the tightness of the canvas. Once you're finished, flip the whole canvas over and tap it with your finger. It should sound like a drum and feel quite taut. If there is any creasing or strange pulling, you'll be able to see it from here. If you mis-stapled or don't have the canvas particularly taut, pull the staples and fix it by repeating the steps in the previous section. The canvas will sag far worse once it is painted, if the canvas is loose.

Use shims or wood wedges to continue promoting stretching. With some canvases, it's appropriate to insert shims into the corner joints to further stretch the canvas. This won't always be necessary, but if you want the canvas to be especially tight, or you think it could be tighter but don't want to take the time to remove all the staples and start over, this can be an excellent way of tightening it a bit more. Wooden shims are very thin shards of wood that you can buy in packs at the hardware store for a few dollars. They usually come in a variety of sizes, which means you'll be able to customize the stretch and fill in the gap if necessary.

Let the canvas rest. After stretching your canvas, it's important to let the canvas rest and tighten up on the frame before you attempt to prime it or paint on it. In a room-temperature area free of excess moisture and humidity, a canvas should tighten up and be firm in about a day or two.

Prime your canvas. After you've stretched your canvas, you're ready to prime it, using gesso or the primer of your choice. Sometimes "tightener" will be added to the canvas and allowed to dry before the primer, and sometimes not. Then, canvas needs to be primed by painting even, thin coats using the brush in one direction. Most canvases should be primed with three coats. Apply one coat and let it dry thoroughly to the touch, then go back over the canvas with another coat. Use extremely fine-grained sandpaper to go over the paint before priming the canvas one more time. Painting the primer on in the same direction allows the canvas to look fairly clean and simple, a great backdrop for your painting. Use sandpaper to flatten any texture or bumps of primer on the canvas.