To the exasperation of the beginner, who wants only to get down to the actual painting, manuals often start with a discussion of what is called the support — the wood, canvas or hardboard to which the paint is applied. Then comes another disquisition on the painting ground, the priming layer that needs to separate the support from the overlying paint.
Ground and support have to be firm enough to support the painting, but not so rigid as to cause cracking. The surface has to be porous enough to allow the paint to adhere, but not so absorbent that all the oils are sucked out. How is this balance achieved? By using traditional approaches of preparing art canvases — they're easy to apply and will save money — or by modifying the commercial article.
In fact both support and ground are important matters. Paint is a reactive substance and will gradually eat into and destroy its support unless protective measures are taken. And not only do supports vary in their resistance to the chemical action of oil paint, they create very different surfaces on which to paint. There is a world of difference between applying paint to a well-prepared linen canvas, and coping with the slippery surface of the pre-primed artist canvas from a local art store. The local product may be cheap and readily available, but all too often it doesn't allow the paint to be handled properly, particularly if that paint comes from a tube. Pushing runny toothpaste around a sheet of glass might be an apt description of the sort of nightmare that the beginning painter faces.
Why don't artist canvas suppliers provide good products to begin with? They do. In general the artist materials companies offer an excellent service, conscientiously balancing general requirements against what customers will pay for. Every years see improvements to old lines, the launch of new products and of free notes to get the best from them. No, the problem lies with the customers — many of whom are hobbyists rather than craftsmen, and so place convenience first.
To repeat: when paint, support and ground have all been prepared to the artist's requirements, then painting becomes a delight, one that has to be experienced to be believed. Effects that are otherwise difficult or impossible to achieve become the everyday skills of the journeyman painter.
Types of Support
Supports need to be solid, durable and stable: they are generally grouped as follows:
Fiberboard (masonite or hardboard) is better than wood, which is better than plywood.
Linen is better than cotton, which is better than hessian. Supports entirely made of cotton will stretch and crack, besides not holding the priming well. Prepared canvases are of variable quality.
Handmade cotton paper is better than handmade paper, which is better than card, which is better than cartridge paper glued to panels.
Stretching a Canvas
Fiberboard (either the rough or smooth side) needs to be sized and primed. Flimsy materials have to be mounted on board. Canvases provide the best surfaces, but have first to be stretched.
1. Purchase the stretcher pieces in the size required, and assemble them, if necessary tapping the corners into right angles with a hammer. Check the angles are square.
2. Cut the canvas or linen to the right size, sufficient for an inch or two of overlap onto the stretcher bars behind. Make sure that the grain of the canvas is parallel to the stretcher bars.
3. Stretch the canvas over the frame — tightly, but not sufficient to pull the stretcher frame out of true. (Canvas pliers will help.)
4. Fasten the canvas at intervals of a few inches on the back of the stretcher bars, either by tacks or (better) by staples. Do this methodically so that an even tension is maintained throughout the canvas.
5. Fold and tack/staple down the overlapping canvas at the back corners of the stretcher bar.
6. Tap the wedges into place, tightening the canvas a little.
7. Check again that the stretcher corners are square and that the grain of the canvas is parallel to the stretcher edges. You can't adjust these (or use the wedges) once the canvas is sized.
Unless acrylic priming is to be used (which not all artists trust, but which can be applied directly to the untreated board or canvas), the surface first needs to be sealed and given the right porosity. Rabbitskin glue is the most popular. Directions are given in the packet, but run something like this:
1. Use one ounce of rabbitskin glue to one quart of water.
2. Heat water and glue over low heat in a container, but do not boil.
3. Cool to room temperature when the glue has completely dissolved: it will have the consistency of jelly.
4. Reheat the size until liquid.
5. Apply the size liberally so that it penetrates the canvas or wood fibres.
6. Allow to dry thoroughly: canvas will shrink a little and be pulled taut in its stretcher.