Strip-Lining, Or How To Stretch A Canvas Which Has Been Painted To The Edges
Every now and then bring people me canvases which have either damaged edges or have been painted with insufficient space around the artwork to wrap it around stretcher bars, as in the picture below.
As you can see, particularly at the top left and bottom right corners, the edge of the painting is very close to the edge of the canvas. To get a good wrap around the stretcher bars it's best to have about 50mm of canvas around the image but in this case it was around 20mm. While smaller canvases may be framed behind glass like works on paper, this is not an option for larger paintings, but they can be still be stretched using a process called strip-lining.
In brief, strip-lining involves extending and reinforcing the edges of the existing piece by affixing additional strips of canvas to the edges using a heat-activated adhesive.
I generally use strips of canvas five inches wide for strip-lining; two inches for the new perimeter and the other three to bond to the existing piece. My preferred fixitive is BEVA 371 film, which is an archival, heat-activated adhesive film. It's expensive, and not always easy to find, but it's the best thing for the job, easy to use and, even better, reversible. BEVA 371 is sold in rolls and comes with a paper backing on one side and a clear plastic covering on the other. Always start with the paper-backed side first and, if you get lost (the paper has a tendency to fall off, particularly once the film has been cut) the side with the adhesive exposed has a slightly dull, matte appearance compared to the protective plastic.
I cut three inch strips of BEVA 371, remove the backing paper and place the film face down on the rear edge of the artwork. Using an iron at a low setting (mine is set to "polyester" in the picture below) and using the backing paper removed previously to insulate the film from the surface of the iron, I make several passes across the length of the strip until it is completely adhered.
With one side of the film now fixed to all four rear edges of the artwork, I now peel the protective plastic from the other and begin to attach the canvas strips. Since I will be heating the adhesive through a layer of canvas this time, I set the iron to a higher temperature suitable for linen or canvas. Much the same as before, I work in a series of passes until the canvas strip are firmly fixed to the artwork with no peeling at the edges.
Now the painting has the additional canvas required to wrap it around the stretcher bars, though it's a good idea to let the adhesive cool before moving on to stretching. I'm not a fan of stretching pliers in general, but I strongly advise against using them when a canvas has been strip-lined. Although the bond created by the BEVA 371 is strong, it's still best to be careful, particularly if the strip-lining has been carried out to repair a damaged canvas. When a canvas is being stretched for display, I see little sense in putting too much tension into it anyway.
One downside of strip-lining, is that you are inevitably left with a fairly obvious join between the artwork and the lining since canvas is quite thick. I have tried to make this less obvious by lining with black strips in this case but I always recommend that strip-lined canvases, once stretched, be displayed in a float frame where the edges can be concealed.