SUPPORTS AND GROUNDS
The physical material you paint or draw on is called the "support." It may be made of glass, plastic, wood, paper, hardboard, concrete, canvas, etc.
A "ground" is a kind of coating put on the surface of the support before you paint or draw on it. "Gesso" is a mixture of various products and is used as a preparation to apply to your painting surface.
Paper is made from wood pulp. Paper contains natural acids that, after time, become brittle and discoloured. These acids can be removed or neutralized and in turn last longer.
Cotton fibre is made from cotton fabric mixed with water and chemicals and beaten to a pulp. The fluid-like cotton material is formed into sheets and, when dried, this becomes "rag" paper. Papers derived from cotton can be made acid free. Some papers can be made from a combination of cotton and wood or cotton and synthetic fibres.
When choosing paper, the most durable papers for painting and drawing are 100 percent rag and pH-neutral or acid-free. The next best choice would be papers that have at least some rag content and are rated as pH-neutral or acid-free.
Canvas is a fabric woven from a variety of natural or synthetic fibres. This support is very good for oil and acrylic painting. The fibres most commonly used for an artist's canvas are linen, cotton and synthetics. Linen is the best choice --but it can be very expensive. Cotton is the second best choice and the cost is a little more reasonable. Synthetics are becoming popular as well. With proper care and handling all three will work well. The weave of the canvas differs from tight-to-loose and fine-to-coarse. A course weave would be suitable for an impressionistic work or rough knife work, whereas a fine weave is suitable for smooth and more detailed painting.
Canvas board is simply canvas glued to a sheet of cardboard. There are two problems with canvas boards. First, the cardboard may absorb moisture from the back, causing the board to warp. Second, there is no acid-free cardboard available these days, which means that, in time, the board may become brittle and flaky. Coating the back with acrylic gesso will slow the process of disintegration.
Hardboard is made by subjecting wood pulp to high pressure and heat --so that the fibres form a hard, compact mass. Masonite is by far the best variety of hardboard and is preferred by many artists (myself included). Use only "untempered" or "standard" masonite board. There are two common thicknesses: 1/4" and 1/8". Use the thinner stuff only for small paintings, as it tends to flex and bend under its own weight. I like to purchase my masonite in 4'x8' sheets at a local lumberyard. It is usually priced far cheaper than at my local art supply store, and if you are prepared with your dimension requirements, you can convince the lumberyard guy to cut the 4'X8' sheet to the sizes you need on the big tablesaw. Keep in mind though, that depending on the size of surface you require, the board is quite heavy and a large painting is considerably heavier than canvas.
To prepare the surface for either acrylic or oil painting, first sand the surface with fine sandpaper to remove any oiliness and to provide some "Tooth" in the hard surface. Rub both sides with a damp cloth and then dry with paper towel until no brown comes off onto the towel. Then, paint both sides and all edges with undiluted acrylic gesso. Paint the back first, then turn the board over and rest it on some thin strips of wood to keep the board's surface from the tabletop. The wet gesso on the back will tend to make the board warp, so paint the front surface quickly to equalize the pull. When completely dry, sand the front to the smoothness you want and wipe clean. Apply a second coat if you wish. Use acrylic gesso straight from the jar for the first coat. For the second coat, dilute the gesso with a little water. The manufacturer's instructions should indicate exactly how much to dilute it by, but about 10 percent water is a common guestimate. You may use as many coats as you wish --but two are usually quite sufficient.
For a large painting you may need to stiffen the hardboard. Lay the board face down on a flat surface and glue wood strips 2" wide and 1/2" or 3/4" thick to the back along each edge. If the board is longer than 36", glue an additional strip halfway between the two shorter edges. Use smooth, straight strips of wood and Elmer's glue. Add some weight to the board such as books (or clamps), and leave until thoroughly dry.
A NOTE ON ACIDITY
Most substances are considered to be neutral, alkaline or acidic. For example, vinegar is acidic whereas Alka-Seltzer is alkaline. If you mixed the two together the result would be neutral. Papers are treated in various ways to counteract the destructive effects of acids. When we buy paper that is "pH-neutral " or "acid-free" keep in mind that many things can effect paper and change its acidity. For example, backing your paper with acidic cardboard or using a mat that is acidic, or even exposure to air (which contains acids) can affect the paper.
True gesso - A mixture of glue, pigment and a chalky filler used as a ground for egg tempera and other paints. This is not the same as acrylic gesso.
Acrylic gesso- A form of acrylic paint suitable for use as a ground for many paints.
Latex Paint- Latex paint actually makes a good ground for hardboard and comes in any colour. The other good thing about this alternative is that it is a cost-effective solution when working on a large painting.
This page was last updated on 09/17/02.