What is the best support for painting?

A. The support in the strict sense

Before beginning to paint, the first point to be considered is to determine which support to utilize. A support can be nearly everything, e.g. a canvas, a piece of furniture, a cave wall, a sheet of paper, a wooden plank, etc. Contemporary painters (of the 20th century) have tried every sort of support, without caring much about their intrinsic quality, so that it’s a pity to see the poor state of many masterpieces in the museums of modern art.

But in the old times (e.g. the “Quattrocento” in Italy), the apprentice-painter spent many years in the workshop of a Master, struggling with the materials, before he might even risk one single stroke of a brush on a painting. So he knew perfectly well what was a good support for painting.

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The supports of the Ancients

Everybody can state the striking fact that the best preserved old paintings are not made on supple canvas, but on rigid wood panels. Nevertheless, those panels, particularly when large, presented many drawbacks.

Ordinary logs cannot furnish broad planks. In consequence, relatively narrow planks had to be glued together to make a wide surface. But butt-joining those planks suitably is not an easy task and the joins always remain a weak point of the painting, even when reinforced with dowels, pegs or wooden butterflyes.

The Ancients also tried to reinforce and hide the joins by sizing on them hemp- or linen-tow or linen canvas. This last system proved to be the best one. Even better was to size a linen canvas on the whole surface of the panel.

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Well-seasoned wood

The planks for making panels have to be thoroughly dry, but the difficulty is to find well-seasoned planks. Unsufficiently dry wood leads to splitting and cracking of the panel. For this reason, the Ancients paid a particular attention to getting perfectly well-seasoned planks for their panels.

Another disadvantage of wood, owing to the unsymmetrical arrangement of its fibers, is that it warps easily when drying. And worse: any wood panel is liable to warp, even made from old and thoroughly dry wood, after that it has been recently cut or planed.

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How to prevent warping

Sometimes, the Ancients tried to prevent warping by backing or cradling the wooden support with other wooden pieces. This technique had for immediate effect to produce a very weighty support, but that wasn’t a problem in the churches of the Renaissance.

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Modern supports

Canvas

Canvas is the lighter of all possible supports, but it’s too supple for preventing cracking of a completely dryed oil film. It becomes particularly evident if you go in a museum and compare the masterpieces of the Ancients, painted on wooden panels, and the more recent ones, painted on canvas.

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Solid wood

Solid wood is very heavy. It splits and warps easily when not well-seasoned. But in our century, it’s nearly impossible to find perfectly well-seasoned wood.

To prevent warping, after being made, any wooden panel has to wait several years before being prepared for painting. It’s no use to take old wooden panels like tables, floors, etc. for painting because such materials must necessarily been reworked before making a panel suitable for painting. And this operation makes them as liable to warping than a panel made of fresher wood.

The surest manner to prevent warping is to cradle the panel, but this operation makes it heavier yet.

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Plywood

Plywood is not so heavy than solid wood, but can very easily warp too and, for this reason, has to be cradled, except for quite small panels.

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Chipboard

Chipboard seems not to be prone to warping. But it is a very heavy support. It's corners and edges are fragile and crumble easily; to prevent this crumbling — and because it’s a very absorbent surface too —, it has to be copiously sized and, yet better, covered by a sticked canvas that is folded over for hiding and protecting its edges and corners completely. Because of its weight, it has to be reserved for small paintings.

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Hardboard

Hardboard is not very heavy. Like chipboard, it’s very absorbent and it's edges and corners are fragile and crumble easily. It has thus to be copiously sized too — particularly its embossed face — and it’s better to stick on it a canvas before painting for making it more solid. It warps easily, but this tendency can easily be counteracted in three ways:

1. Sticking a canvas on both faces of the panel. If necessary, putting two coats of cloth on the bulging face of the panel ¹. One has to paint the back of the panel with as many coats of the same size, the same gesso and the same paint as its front so that these coats work the same way on both sides of the panel.
   
   
   1. Why? Simply because a linen (or cotton) cloth got wet by a watery glue shrinks when drying, what exerts a mechanical traction on this face of the panel, like a string that bends a bow.
   
   
2. Because hardboard is supple, a not too large panel can be prevented to warp simply by embedding it into a frame, even before beginning to paint in oils on its front. Nevertheless, in the case of a larger painting, this can be sufficient for the borders of the panel, but not for the center, which can all the more bulge out as the panel is larger. Then the third remedy becomes necessary.
3. Cradling the panel with battens, as I will explain below.

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What should be the ideal support for oil painting?

The ideal support for painting in oils:

1. shouldn’t be too supple for preventing cracks in a completely dry oil film;
2. shouldn’t split, crack, nor warp;
3. shouldn’t be too heavy, particularly for large paintings.

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Canvas?

Except for point #1, canvas is the best support. Nevertheless, if you utilize an alkyd medium for your paintings, the paint film will possibly remain supple for ever, and never begin to crack. But these mediums came too recently on the market for being absolutely sure of it: only with the passing of time our descendants will be able to better judge.

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A good compromise

For preventing future cracks in the oil film, one of the better compromises could be a supple support combining the hardness of wood and the suppleness and elasticity of canvas, without being too weighty.

For small works, plywood could be a good solution but larger formats warp very easily, what prevents the painting to be normally and correctly framed, making soon necessary to cradle it, but this makes the painting very heavy. That’s why I consider hardboard to be better than plywood because this latter, on the contrary, stays gently enough supple for easily adapting to a rigid frame, even after warping. So I stick very carefully linen canvas on hardboard.

Besides, the association linen canvas/hardboard has two advantages: the board prevents the canvas from becoming slack and the canvas prevents the edges of the board from folding and scratching and its corners from chipping.

The artistic viewpoint

And yet, from an artistic viewpoint, canvas has an unique advantage on every other painting support: the structure of its surface presents an extraordinary receptiveness to the matter of the oil colors and to the strokes of the brush.

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When cradling becomes necessary

Sometimes, in spite of every precaution, a panel begins to warp. Then, the only solution is to size a framework of crossed battens on the back of the panel.

The figure below shows how to make this cradling.

• “A” is the panel to be painted.
• The first layer of battens is “B”; they are sticked on the panel. Never use nails nor screws because these can rust (brass or other metallic ones can corrode too), what can lead to discoloration of the gesso. And if you retire the screws after drying of the glue, they leave after them holes in the panel, wich remain weak spots for ever, even if you fill the holes with wooden paste or something else. Furthermore the nails or the screws create unequal tensions on the panel, what can be dangerous for the paint film.
• “C” is the second layer of battens. These can be nailed or screwed on layer B”. Even if you use nails or screws, it’s wise to size every layer to the preceding one.
• For each layer, the number of battens depends on the size of the painting.

The battens are made of plywood about 1 cm thick (about 0.4 inch) and 7 to 10 cm (3 to 4 inches) wide. It’s probably better not to stick the first layer “B” on its whole lenght on the panel ¹:

One can make use of little wooden squares — preferably the same plywood as the batten, but it can be thinner (about 0.5 cm or 0.2  inch) — as shown in next figure. One can use e.g. 3 little wooden squares per batten (this depends on the size of the work). The squares (“D” on figure below) are to be sticked (without nails nor screws) on the panel. Battens “B” can be nailed or screwed on the squares, at least until the glue is completely dry (48 h).

The glue to be used is ordinary synthetic wood-glue (white glue made up of a dispersion of vinylic resin in water). When completely dry, this glue is so strong that it becomes even more solid than the wood: if you try to break it, the wood will break, not the glue.

Advantages of this solution

Even after cradling, provided you use for it not too thick plywood ¹, the panel will not be too heavy.

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B. Preparing the support before painting

After the choice of the support, the first and most important problem is to know how to prepare it before painting.

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Sizing

It's necessary to size every wooden or canvas support for preventing the oil of the color to undermine the support — particularly canvas. This sizing plays the role of an isolating layer between the color film and the support.

The Old Masters employed organic natural sizes (e.g. “goat-skin” glue). I consider that the modern resin dispersions/emulsions have the best chances to be much more stable in the curse of the centuries than the natural products of the Ancient Masters, which were subject to many hazards: melding, rottenness, insects, etc. The modern resins are almost chemically inert and beyond every alteration of that type.

Besides, the natural sizes have a tendency to become more rigid, even breakable, with the time. On the contrary, modern resins stay absolutely supple, what is very important to prevent splitting and cracking of the picture film.

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Gessoing

After sizing, it’s now necessary to apply a “gesso” on the primed support. “Gesso” is the Italian name for gypsum. In the old times, gesso was a kind of plaster which presented the inconvenient of being very easily broken, but had the advantage of being very lean (= without fat), when it was prepared by dispersion in an organic size. It was thus necessarily applied on a rigid support.

When the painters began to paint on supple canvas, they abandoned the too rigid gesso for an ordinary white oil paint, with the disadvantage of constituting a more fragile, brittle and yellowing support for the further layers of paint, owing particularly to the fact that it was a fat surface.

The centuries experience has shown that works painted on lean gesso stand better the test of time than those which were painted on a fat support. The rule of “fat over lean” is the fundamental rule for an oil painting that will stand the test of centuries (see “painting”).

Since the advent of acrylic colors in the second half of the XXth century, there have appeared canvases prepared with lean acrylic gessoes.

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10 years or some centuries?

The tradition has maintained the word “gesso” for any sort of coating for artistic paintings. Today, for “gessoing” their panels or canvasses, many painters utilize lean industrial products made for house painting. This is a cheap solution and the results may like excellent but we must keep in mind that these paints are conceived for lasting 10 or maximum 20 years; who can guarantee they can stand the test of time for a longer period?

Since some years, more often than not, I use a “gesso” which I prepare myself with white pigments of the best quality, dispersed in an watery emulsion of modern synthetic resins (quality “for artists”) that stay supple when drying. Before, it were commercially prepared acrylic gessoes of the best brands, or even already gessoed canvases, sometimes even already stretched on a frame. In any case, these were lean supports: the best possible for the further paint layers.

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