It’s a question we get often, and the answer is really simple. When do you need a keyable stretcher? Always! In this post, we’ll talk about stretcher keys, what purpose they serve, and how to assemble a keyable frame.
Using a fixed frame for your canvas greatly increases the likelihood you’ll have to restretch and reframe it at some point, due to the natural flexible nature of canvas. In fact, oil paintings often need major conservation work within decades of completion. Keyable stretchers safeguard your paintings and canvas photo prints from wear that occurs in all canvas over time.
What are stretcher keys?
A key is a critical stretcher frame design feature that allows you to adjust the tension of your canvas in small increments.
Canvas will absorb moisture over the years, causing it to expand. When your canvas is allowed to stretch and sag, the resultant damage to the layers of oil paint can be dramatic.
Stretcher keys are precisely manufactured to fit in the mitered tongue and groove joints of a properly constructed canvas frame. When you adjust the keys (called ‘keying’ your frame), your frame expands slightly to pull the canvas tight again.
Are all keyable stretchers the same?
Stretcher keys keep your canvas tight and protect your painting or photo print over time.
Absolutely not. Keys are one component of a solid foundation for your work, but you also want to make sure your stretcher frame has:
- A beveled or tapered profile, with a slope on the front face of the bar to provide extra space behind the canvas and prevent contact with the bar or cross brace.
- Adequate cross bracing to support the size of your canvas, with cross braces mortised and tenoned for strength and fit.
- Bars expertly constructed of clear grade, straight grain wood with a moisture content of 8% or less, free of knots, splits and other defects.
- Precision tongue and groove joints with rigid, square corners.
If your project is wider or taller than 8’, you’ll also need laminated stretcher bars and a couple of other heavy duty design features you can learn more about here.
How do I assemble a keyable stretcher frame?
It’s easier than you might think! With your stretcher bars and keys, you’ll receive a set of instructions to help out. You’ll get step-by-step advice putting the stretcher together, with tips to help you increase the friction in loose joints and prepare your frame for transportation, by spot welding your stretcher keys.
You’ll need a few tools you probably already have in your house or shop to put your keyable frame together:
- measuring tape
- carpenter’s square
- staple gun
- mallet, or a regular hammer and a mallet head
Want to see a keyable frame assembly in action? Check it out:
If you’re looking for information on how to assemble a floater frame with dovetailed keys, you’ll find that tutorial here.
Can I get keys for a custom canvas?
Absolutely. We make clear ash hardwood and birch plywood keys for custom canvas frames of all shapes and sizes. Send in a sketch showing your stretcher shape and dimensions and we’ll get you a quote — see this page for more details on sketching your frame.
- Keep your canvas tight and protected even on large, irregularly shaped stretcher frames like this one.
- If you don’t have a stretcher yet but are planning an irregularly shaped or unusually large project, our CNC technology might be just the ticket. Most shaped frames are fixed, which doesn’t allow for adjusting your canvas tension over time.
- We fabricate truly keyable oval, round and arched 2D or 3D frames with cross braces included, and optional gravity bars available for hanging.
Want to learn more?
- Read more expert articles on the UCSART Art Blog
- Browse a selection of keyable stretcher frames online
- Talk to an Upper Canada Stretchers expert about your next project