What makes an ideal support for an oil painting? In Virgil’s opinion: a rigid panel rather than stretched canvas or linen. The reasons are explored on this page.
Editor’s Note: See Virgil’s discussion of cloth supports and rigid panels in his book (pages 115-119).
Once asked what his favourite surface and support would be, if cost were not a factor, Virgil replied: “Nylon (it’s actually polyester) or Belgian linen, glued to honeycomb aluminum panels with a reversible conservation adhesive, primed with white lead in linseed oil.” Most of his work is done on lead-primed linen glued to rigid panels, mainly because he prefers that particular texture.
Why he prefers a combination support whereby canvas is attached to a rigid panel: “In addition to stabilizing the paint layer, and thereby reducing the likelihood of cracking, it allows the canvas to be more easily removed from the panel with the painting surface intact, should the panel itself ever develop problems and require placing.”
For a reversible conservation adhesive, Virgil recommends BEVA 371 Film. Please see the technical note at the bottom of this page.
Stretched Textiles: Cotton Canvas or Linen or Polyester
I continue to maintain that stretched textiles are not the best support for oil paintings, and that linen is better than cotton as far as long-term durability is concerned, if one insists on painting on stretched cloth. Polyester will probably outlast them all.
The drawbacks to stretched canvas as a support include susceptibility to damage from the rear, rotting, mold, mildew, and slackening, which increases the likelihood of the paint cracking after it has lost its flexibility.
With polyester canvas, some of these concerns are eliminated, but not susceptibility to damage. Polyester is less susceptible to changes in relative humidity (RH) compared to linen and cotton. They are likely the best choice for canvas.
The drawbacks to stretched canvas as a support include susceptibility to damage from the rear, rotting, mold, mildew, and slackening, which increases the likelihood of the paint cracking after it has lost its flexibility. With polyester canvas, some of these concerns are eliminated, but not susceptibility to damage.
Whereas conservators have had plenty of time to devise ways of treating the defects common in old oil paintings on stretched canvas, only a few paintings will find their way to a museum with a top-notch conservation department before they have begun to deteriorate. The rest will be in private collections whose owners might not know to whom to take their paintings for treatment, if they even realize that they need it or are willing to spend money to get the work done, or in galleries whose owners are just as happy having the cheapest local hack restorer make the pictures look good enough to sell, with no concern for the consequences of it after the check clears.
I know of no pre-stretched, pre-primed canvas that I can recommend for any serious painting that’s intended to last as long as an oil painting should last. Canvas glued to panel is much better.
Gluing the canvas to a rigid support is a good idea, and if a reversible adhesive is used, even better. The painting then has a better chance of lasting much longer.
When asked what wood he uses for stretchers, Virgil replied: “For stretching canvas, the very best stretchers I have found are Museum Bars from John Annesley Company, in Healdsburg, California. They’re made from basswood, and have adjusting hardware in the corners and at the ends of the crossbraces for precise adjustment of canvas tension.”
Gator Board or Foam Core
Gator Board isn’t a suitable substrate for fine art oil paintings. Aluminum composite or wood panels are a better choice.
The problems I see with Gator Board are the plastic foam being subject to denting and breaking down over time, and the rotting of the paper covering it. Knowing, as I do, that many excellent painters are not up to speed on the current level of scientific knowledge regarding oil painting materials, the fact that X number of top-notch painters use a given material is not a reliable testament to the actual quality of that product.
Additional notes: Virgil concurs with George O’Hanlon (of Natural Pigments)’s advice: “Gatorboard and Foamcore are products with low density cores with cellulose fiber veneers which do not make stable supports for mounting canvas. Avoid supports containing materials that are responsive to the environment, such as wood or paper (cellulose fibers)”
Masonite and Hardboard Panels
The main drawback to Masonite and other pressed-wood panels [Presdwood is another brand name] is their susceptibility to damage at the corners if they are dropped. This is why I think it’s a good idea to glue wooden braces to the back along the edges.
There are different kinds of hardboard on the market in tempered and untempered varieties, so we can’t realistically expect a simple answer to suffice for all types of hardboard that are referred to colloquially as masonite. Masonite is actually one brand among several companies who offer hardboard. I’ve painted on some that were tempered, as far back as 1980, and so far no problems have shown up, but that was only 37 years ago.
[Some perspective: these panels are a better choice than stretched cotton canvases.] There are panels available in varying degrees of quality, and even the worst of them are probably better than the average pre-stretched, acrylic-primed cotton canvases sold at art supply stores. Or you can make your own by buying pressed-wood panels, cutting them to the desired sizes, and applying the ground of your choice. These, too, would most likely be better than the aforementioned store-bought cotton canvases that most people use.
The substrate’s purpose is to keep the paint layer stable, so it will be less susceptible to cracking when it reaches the age when it’s no longer flexible.
Seal the wood with polyurethane before gluing canvas to it. The polyurethane helps protect the canvas from the acidity of a wood substrate. Unless isolated from the canvas, the acids will accelerate the rotting of the linen or cotton canvas.
Virgil does not recommend painting directly on wood or hardboard. “I wouldn’t recommend painting directly on hardboard sealed with polyurethane. There are several varieties of hardboard, some tempered and some untempered, so we may reasonably expect there to be differences in acidity, hardness, and absorbency. Untempered wood can be primed with a glue-chalk ground without needing to be sealed, and tempered can be primed with an alkyd ground or white lead in linseed oil with good results if it’s done right.
Unreinforced hardboard panels are vulnerable to damage at the corners if they’re dropped, but once secured in a frame, that danger is essentially eliminated. I’ve found 1/8-inch thick hardboard suitable for sizes up to 16 or 20 inches, but larger than that they are less rigid unless there is a bracing framework glued to the back around the edges. 1/4-inch thickness works better in 18-inch and larger sizes, since it’s not as flexible as the thinner panels.
Re: Plywood. Don’t paint on bad plywood with splinters. The top ply will probably continue to detach. I wouldn’t trust this to stay together. I would remove all the loose bits, then fill the low spots with automotive body putty, sand it smooth, then glue a piece of canvas to it using a reversible adhesive. That way the painting can survive beyond the deterioration of the plywood.
Remember: Water causes wood to swell and sometimes warp. PVA is water-based. The top veneer of plywood is thin and reacts badly to water. Some plywoods are better than others for this application, but I doubt any of them are ideal as supports for oil paintings unless canvas is glued to them, and the painting is done on the canvas.
Painting in oils on plastics has to be considered experimental, essentially a gamble on the future condition of your paintings.
Plastics are not made with long-term durability in mind.
Plastics are complex in their chemistry, and my understanding is that among the ingredients are hardening agents and perhaps other things that cause the material to change over time. I’ve seen enough old plastic that had grown brittle and crumbled to cause me to be leery of plastic as a support for oil paintings.
Aluminum Panels (aka ACM panels)
I like the idea of honeycomb aluminum as a substrate for canvas, but not for painting on it directly.
The advantage: its lighter in weight compared to wood and insects don’t eat it.
The disadvantage [besides cost and limited availability]: Aluminum can oxidize underneath paint, and will shed the paint at some point, as can be seen in junk yards where old automobile or motorcycle parts made of aluminum reside. There might be ways of treating it, perhaps anodizing or some other, but until it has been tested for long-term performance, I’d consider it risky. Canvas glued to an aluminum panel would be less risky, in my opinion.
The only metal I’d have confidence in as a painting support would be copper.
Historically, oil paintings on copper have been done using an oil ground of white lead in linseed oil or painted on in oils directly on the copper. These paintings have generally held up quite well. I would be leery of applying any water-based ground such as acrylic to copper, because it has no long-term history to assure me of its soundness. Thus it’s essentially a gamble with the future condition of the painting at stake, and unnecessary.
Remember Ockham’s Razor: Essentia non sunt multiplicanda praeter necessitatem, which translates roughly to “It’s best not to make things any more complicated than they need to be.” Copper has a great affinity for oil paints. Why introduce a layer of a different chemistry between the copper and the oil paints?
Adhesives: BEVA 371 Film
BEVA 371 film is a heat-activated adhesive that was originally developed for relining old deteriorating or torn canvases with a new structurally sound canvas. It can be applied to paper, canvas, textiles, films, wood, metal, plaster, and panels. It comes in rolls of 27″ and 54″ wide and 1 mm or 2.5mm thicknesses. It can be applied to a support using a household iron. The adhesive becomes activated at 150 degrees Fahrenheit (65 degrees C). The adhesive can be reversed with heat or solvents.
You can use 2 pieces of 27-inch BEVA 371 film to cover a larger area easily. As for the choices of thicknesses of the film, heavier canvasses would probably be better served by the 2.5 mm, and possibly the 1 mm would be adequate for lighter weight, tighter weave canvas, provided one 1 mm film is attached to the panel, and another 1 mm sheet of BEVA 371 film is attached to the back of the canvas before being bonded together by heat.
Basic instructions on how to use BEVA 371 film
A video demonstration on how to adhere linen to a panel using BEVA 371 film
Backing Boards for Paintings on Canvas
As noted above in the Stretched Textiles section: “The drawbacks to stretched canvas as a support include susceptibility to damage from the rear, rotting, mold, mildew, and slackening, which increases the likelihood of the paint cracking after it has lost its flexibility.”
For these reasons, the reverse of paintings on canvas or linen should be protected.
“One drawback that is often associated with flexible supports is that they are more susceptible to being damaged by physical contact (e.g. tears, impact cracks, punctures, etc.) In addition, flexible supports are more likely to respond to changes in the environment, giving rise to draws in the corners, an overall loss of tension, and other planar deformations. Such damages can lead to both short and long-term condition issues and can affect the stability of the paint and ground layers. Because of these issues, artists are highly encouraged to affix protective backing boards to the reverse of their paintings.”
2) The Canadian Conservation Institute (CCI) offers some excellent notes on how to apply a backing board in this online document. It offers some solid reasons why artists should make an effort to do this:
All paintings should have backing boards as a preventive conservation measure. Installing a sealed backing board on an auxiliary support (stretcher or strainer) will:
- protect the painting from mechanical damage (e.g. puncture and tear) from behind
- prevent dirt and debris from falling between the lower bar of the auxiliary support and the canvas
- buffer fluctuations in relative humidity (RH) by enclosing the back of the painting (e.g. reduce the risk of cracking caused by RH fluctuations [day–night cycles] and by low RH conditions)
- decrease the painting’s response to shock (e.g. reduce the risk of cracking if the painting is dropped)
- reduce the vibration of the canvas in transit
- block airborne pollutants that can damage and thus weaken canvas supports
- discourage the practice of attaching labels to, or writing on, the back of the canvas