Ever wondered how to stretch canvas or canvas prints and don't know where to start?
You've come to the right place. I've stretched hundreds (not exaggerating) possibly even thousands of canvases of my own and for other customers when I worked in a custom framing shop. It's one of the more simpler tasks for a custom framer and I'm happy to show you what I do and what works for me. Other people may have other methods, you have to find the one that works for you.
I'll talk you through the entire process, from measuring and cutting your own stretcher bars, to stapling the canvas into place and giving it a professional finish.
Tools & Equipment needed; blank canvas or canvas print, ruler, pencil, stretcher bars, chop saw, miter/corner clamps, wood glue, nail gun & nails, staple gun and upholstery staples, canvas pliers, canvas tape, drill or screwdriver, hangers & screws, and wire.
Step One: Measure for the Stretcher Bar Size
If you're stretching a blank canvas, you probably already have a size in mind, so you can skip to the next step!
If you already have stretcher bars assembled, you can skip to Step Four.
If you're stretching a canvas that is already painted, or a canvas print, you'll need to stick around for this part.
Lay your canvas flat out on a clear work surface.
I prefer to use a long ruler over a tape measure for accuracy and to avoid and 'slack' in the tape.
From the edge of the image, I come in about 1/8" and start my measurement, finishing an 1/8" in from the other end too. This is because I don't want any blank canvas creeping to the front.
So, for example, if my image is 30" x 19 1/2", my stretcher bar will be cut to 29 3/4" (30 - 1/8 - 1/8") x 19 1/4" (19 1/2 - 1/8 - 1/8").
In the photos below, I have already moved my ruler in 1/8" and will come in 1/8" from the other edge, so my stretcher bar for this length needs to be cut to 24 3/16" (24 7/16 - 2/16 - 2/16")
Make a note of this measurement and measure the other side. It's important to take as accurate measurements as possible.
Step Two: Cut the Stretcher Bar
Stretcher bars look like cheap wood, and indeed, they mostly are compared to other frame mouldings, but they have a crucial difference from the 1x2" at your local hardware store. They have a rounded lip on them, pictures below, and have been kiln dried to prevent warping. The important lip prevents wear and tear on the canvas as wood and fabric expand and contract with changes in temperature and humidity throughout the year.
I recommend picking up lengths from your local framing shop.
Cut one end of your stretcher bar length at a 45° angle; the lip should be face up and flush to the back of the saw. It'll end up on the front of the stretcher bar and the outer edge.
From the cut, measure out one of your lengths and make a mark.
Flip your saw around so that the 45° angle is the other way and chop at the mark you made. The lip should be on the longest side of the stretcher bar. See pictures below.
Repeat for all 4 lengths to make a frame.
Check that your matching lengths are the exact same size to each other, so you don't get a trapezoid effect frame.
Step Three: Glue the Stretcher Bar
Take one of your longest lengths and one of the shortest lengths of stretcher bar you just cut.
With the lip of the bar face up, glue them together in the miter/corner clamp, squeezing for a very tight and secure fit.
Make sure the lengths are positioned so they form a nice 'corner'.
The corner should be flush in all directions; adjust if part is sticking ahead, up or down. See examples of 'good' and 'bad' corners below.
Repeat for the other long and short bars, leave to dry for a minimum of 20 minutes.
Once the glue is dry, you should have 2 identical L shaped bars, (corners 1 & 2 pictured below).
You can glue corners 3 & 4 at the same time IF you have 2 mitre clamps that are perfectly level to each other, and I mean PERFECT! if they're not, you're setting yourself up for all kinds of problems.
At this point, I position myself at eye level to the clamp to make sure my bars aren't gluing away from each other in a weird direction and adjust accordingly. This is how you can make sure your canvas will sit flush against the wall without a corner sticking up.
Once dry, nail each corner with a nail gun to prevent the bars from coming apart at later date.
For Larger Canvases; Add a Cross Bar/Support Bar
For larger canvases I like to add a support bar to prevent the stretcher bar from bowing in under the tension from the stretched canvas.
Measure the distance between the inside of the bars so you know how long the support bar should be. Measure at one end for accuracy, we know that length is correct. If you measure in the middle and your bars have a slight bow in or out, you won't know. By measuring the end, you can correct any flaws in the stretcher bar.
Cut your cross bar; a piece of 1x2 is fine for this.
Measure to find the centre of your stretcher bar length.
Glue the cross bar into place, secure with clamps if necessary for a tight fit. Make sure it isn't protruding in front of the lip of the frame, otherwise your stretched canvas will rub against it.
Step Four: Positioning the Canvas against the Stretcher Bars
This part is a bit finicky and requires patience, but it pays off in the long run!
Place your art work face down on a clean work surface.
Roll the excess canvas back until you can just start to see the image. Create a crease just inside the image (1/8" max) and repeat for each edge. Pictures below.
With the image still face down, place your assembled stretcher bars inside the creases, lip face down, so it's touching the back of your art work.
The creases you just made will help to guide the stretcher bar into place, ensuring the image is lined up with the edge of the bars. You can 'wiggle' the canvas and bars around until they feel like they're lined up with each other.
Gently position the excess canvas of the longest length along the edge of the stretcher bar and fire your first staple into the centre of the length. Pictures below.
Then do the opposite side by using the canvas pliers to pull the canvas tightly against the frame. Before you fire in the second staple, now is a good time to have a look at the corners on this length, and make sure you can see the image coming around it slightly from both sides.
If you have excess image or none at all on one side, you'll want to reposition before you fire in the second staple. If it's out by a long shot, you might need to remove your first staple and try again. Like I said, this part is finicky.
Once you've got a staple on opposite sides, use the canvas pliers to pull the canvas tight on a short side and fire a staple into the centre of the length.
Repeat for its opposite side.
You should now have a total of 4 staples holding the canvas in place, one in the centre of each edge.
Check your corners again, just to be sure you can see a little of the image wrapping around. It's much easier to take out 4 staples at this stage rather than ripping the whole thing apart later and having to start from the beginning, weeping and cursing as you go, questioning your life choices.
Step Five: Stapling the Canvas
Pro tip: I angle my staples at 45°, to avoid the staple ripping through the thinner part of the canvas grain.
From here, armed with canvas pliers for each shot, go back to the first staple, position you pliers about 1-2" on one side of it, pull tight and fire a staple, then the other side of the original staple (you should now have 3 staples centred on this side). Photos below.
Rotate the canvas 90°, and repeat, working your way around the canvas.
Keep rotating and adding a staple to each length on either side of the previous staples, adding at 1-2" distances, until you get near the corner. This ensures your canvas is stretched from the middle, out, for an even and tight stretch.
If your canvas is a long rectangle, you might want to add 2-3x the staples on the longest lengths, so you approach the corners at a similar pace to the short length.
Step Six: Cut off the Excess Canvas
I prefer to cut off excess canvas, by slicing with a blade flush to the back of the stretcher bars.
You can staple the excess canvas to the back of the stretcher bar if you prefer. In fact, that is the best thing to do for a priceless work of art.
In the unlikely event you're stretching a highly coveted original piece of art work from the renaissance, I recommend taking it to a professional for conservation purposes!
Step Seven: Staple the Corners
Corners are much easier to deal with if you've removed excess canvas.
There are a couple of ways you can secure the corners, I like to fold the corner in on itself for slimmer bars, but for deeper bars I like to trim the centre of the corner to get rid of extra bulk.
It's really hard to explain, so I hope the two sets of pictures make sense. Once folded, secure with a staple.
Step Eight: Is it a Good Stretch?
Your canvas should now be nice and tight and if lightly flicked with a finger, should feel a bit like a drum skin. No ripples on the edge, no sags or loose parts anywhere.
Your image should go all the way to the edge and round the corner a little (no need to worry about this if you're stretching a blank canvas).
If you can check the box on both these things then well done, the hard part is over!
Step Nine: Finishing Touches
If you're not going to frame the canvas and don't like exposed staples, you can cover them with a canvas tape.
Canvas tape comes in black or white and can be found at your local frame shop.
I start at the bottom and work my way around all 4 sides, slightly overlapping the tape where I started.
Alternatively, if you don't like tape or exposed side staples, you can staple your canvas to the back of the stretcher bars to create a 'gallery wrap'. I don't recommend this for beginners though, as it's more difficult to get the canvas lined up perfectly or as tight as it should be, as you're stretching the canvas around 2 edges of stretcher bar.
Add a hanger, place on the wall, stand back and admire your handiwork 😉
Stand Back and Admire!
