Every expert artist knows that if you want to create a painting with longevity, you must begin with high quality canvas. On the flip side, every seasoned artist also knows that even the most splendid and well-protected canvas can begin to weaken after years of transport, display, and exposure to elements such as interior humidity and dust. And then there are those “freak” accidents that may result in tears or holes in the canvas. Depressions in the paint film (known as “cupping) or other dents can also occur when a large canvas has been stacked next to a slammer one that has pushed against it says Ray Smith, author of The Artist’s Handbook.
Although it might be a good idea to leave major repairs to a conservator, many artists may attempt to do the repairs themselves. If you have the time, a steady hand, a little patience, and the right tools and techniques, it is possible to complete a successful DIY repair. Fortunately, Smith offers a range of repair applications that can be used to fix varying degrees of damage. Let’s start with repairing small holes.
Repairing Small Holes
1. Prepare the canvas by moistening the back of the wounded area slightly and flattening it with weights. This allows the damage to be assessed more easily and any wounded areas to be brought together, says Smith.
2. Neatly cut off any loose threads or frayed edges of canvas.
3. Cut a patch of canvas larger than the area of the hole.
4. Feather the edges of the patch to assists its invisibility when seen from the front.
5. Attach the patch to the back of the canvas using BEVA adhesive. This adhesive is available in film form or as thick, viscous liquid.
Tip: If a hole is evident from the front, it must be filled to the level of the rest of the canvas with a proprietary, fine-surface filler paste incorporating PVA, which gives flexibility. This can be sculptured to the texture of the surrounding canvas, and primed and painted by the artist to match the rest of the work.
Resolving Depressions or Other Surface Deformations
According to Smith, artists tend to sponge water onto the back of the canvas in the area affected. This can cause shrinkage and result in pulling out the bulge. However, modern canvases woven on power looms have a very tight weave and are therefore more prone to shrinkage, so too much water on the back of the canvas will shrink it to the point where, ultimately, the ground will begin to flake off. The answer, says Smith, is to use moisture as sparingly as possible.
1. If possible, lay the canvas on a low-pressure lining table. This helps to relax and flatten canvases than have been deformed.
2. Dab the canvas with a moist “squeezed-out” sponge only.
3. Protect the surface of the painting by laying a sheet of clear film.
4. It may be helpful to place a book under the horizontal canvas up to its surface level, where the bulge has been treated.
5. Put another book on top to help flatten the bulge.
Tip: Did you know that conservators used small amounts of refined sturgeon’s glue to stabilize the detaching paint from Van Gogh’s A Wheat Field, with Cypresses? They also used a low-pressure lining table, which provided suction, humidity, and warmth during the process.
Treating Degraded or Weakened Canvas
There are a number of methods that can be used to treat degraded or weakened canvas. Let’s start with the “striplining” method.
The most common treatment for a very degraded or weakened canvas is full or partial lining, says Smith. Because a weak canvas may only be weak around the edges where there is stress at the edge of the stretcher bar, he says, only the edges are strengthened. This is known as “striplining.” This process does not involve any major treatment to the center of the painting.
1. The method uses ethylene vinyl acetate copolymer adhesive—incorporating microcrystalline waxes, such as BEVA 371. A lining that uses such an adhesive requires heat and is normally applied on a flat, heated metal surface known as a hot table, says Smith.
2. The painting is pre-stretched, as is the lining material, which may be the traditional linen, a glass fabric, or polyester sailcloth.
3. The BEVA adhesive is available as a thin, uniform film that can be peeled away from the backing sheet and placed between the back of the painting and the lining material.
4. The hot table activates the adhesive and a vacuum pressure brings the surfaces together.
Tip: In the early years of the process, too much pressure was used, says Smith, resulting in paintings with a corrugated texture. Since this was first noticed, the pressures have been considerably reduced.
During the relining process, the front surface of the painting is faced with tissue paper and glue to protect it, says Smith. In the case of relining (where the old degraded lining has to be taken off the back of the canvas), this facing is essential for its cushioning protection. It also holds the paint in the correct place on the painting in the event of delaminating.
An old lining is removed by being pulled off by hand in narrow strips. All traces of the old glue are removed from the back of the old canvas, either by very careful washing with warm water or by scraping with a utility knife.
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Mayer, Ralph. The Artist’s Handbook of Materials and Techniques. 5th ed. New York: Viking, 1991. Print.
Smith, Ray. “Conservation and Framing.” The Artist’s Handbook. 3rd ed. New York, NY: DK Pub., 2009. 330-31. Print.