Using "Keys" to (Re)Stretch Canvas
 

A question was raised in another thread concerning a sagging (

Heavy duty stretchers
 

Thank you Steven for taking the time to post this information. You mentioned heavy-duty stretchers. At about what size painting is it recommended that one uses the heavy-duty stretchers? I start with unprimed linen canvas, then size it and prime it after it's on the stretchers.

Thank you,
Joan

Sorry, Joan, I can't cite any firm guidelines. Perhaps another member has some working lengths that he or she can offer for reference.

I recently did a landscape that was about 38 inches wide. I think that's too long a span for only a standard stretcher bar (or "strip"). There's simply too much deflection in the center of the bar when you hank down on those canvas pliers. But in this case I was unable to use heavy-duty strips because the clients already knew what frame they intended to use, and the extra-thick profile of the heavy-duty strip wouldn't have worked aesthetically, so I chose to simply add a cross-brace. {I haven't delivered the painting yet, but I've been informed that the client, while demonstrating the intended location for hanging the painting, dropped the antique frame and damaged it beyond repair.]

Certainly by the time you're working with dimensions of 3 or 4 feet each way, I think you want to be using heavy-duty stretchers. That's roughly the size of this portrait (the posted image is cropped), on which I used both HD stretcher strips and a cross-brace -- perhaps excessive, but I was using a heavy double-primed Belgian linen and I knew I was really going to lean on those pliers to get that canvas stretched, and then I wanted it to stay there. I knew I would be making my own frame and that it would be quite wide and deep, so the thick profile of the HD strips wasn't a problem.

Besides considering the deflection over a long span, I just look at the size of the proposed piece, realize that I'm going to ask the stretchers to support a canvas drawn tight as tympani heads over that area, and ask myself if the standard size looks and feels strong enough. Not very scientific, I know.

Frames
 

Thank you for your reply Steven. I guess when I tackle about a 33" x 28" portrait I should probably use the heavy duty stretcher bars? I hadn't really thought of that until I read your post.

I once tried to use an existing frame by making my own stretcher bars to fit the frame. I just glued them and nailed them together at the corners, I used 1"x2" wood and cut it to exactly what would fit in the frame. I stretched the canvas and put the sizing on. Then it stre-e-e-e-tched very tight and my home-made frame sort of twisted as the canvas tightened. Oops.

Is there a way to make a frame for a specific sized frame if the frame opening is not in whole numbered inches, e.g., 33 1/2"? I suppose there is some machine out there that allows one to make their own French mitered corners, but that's not for me.

I'm asking because I often see beautiful old frames that were custom made to fit who-knows-what and I can just see a portrait in the frames. Not being sure how to fill the frames doesn't stop me from buying them, and I have quite a collection now!

You mentioned making your own frame. That interests me. That may be a subject for a whole new thread, but I would like to hear about that. I am getting ready to do a simple painting/portrait for my son's room and it's 30"x40". A simple black frame would look great around it but I haven't thought much past that point. I used to frame my own pictures at the old U-Frame-It stores here in Houston, but they've done away with those. I suppose with a miter saw I could make a frame - I'm talking about a simple frame for my son's room, nothing fancy.

Thanks,
Joan

P.S. I would love to see that landscape. I'll bet the clients were pretty upset that they ruined their frame. What a mess.

Yes, the twisted stretcher support is precisely the problem.

Your proposed 33 x 28 inch portrait seems right on the line to me. You may be able to use standard stretcher strips, but personally I'd cross-brace the longer dimension. You're rarely sorry to have built something too strong.

So as not to get too far afield from the thread's topic, I won't get into building frames, but I find it a lot of fun to creatively puzzle together various moldings into a custom frame. Perhaps another thread, another time. Meanwhile, this type of built-up frame is nicely illustrated in How To Make Your Own Picture Frames, by Hal Rogers and Ed Reinhardt.

Lastly, on the odd-length stretchers. That's exactly what I ran into on the landscape (a problem subsequently mooted by gravity). I bought a pair of stretcher strips 2 inches longer than needed, then somewhat painstakingly used a Japanese handsaw to cut new French miters into them at the custom length. Interesting once, but I don't wish to make a habit of it.

Just a small point to make. If you using any percent of zinc oxide in your white, then your finished paintings should be on a panel. With time the zinc oxide will embrittle your drying oil binder. Results will be variable if you're mixing in a lead white with the zinc oxide.

Steven, I forgot to thank you for this! Thank you!;)