Support for your paintings
Support For Your Paintings
A painting, like a house, needs a good foundation. If you are a professional artist or are interested in permanence, you need to consider that what you paint on is the first concern for insuring that your expressions will last. To my knowledge there are no commercially made canvases or panels for artists painting in oils and acrylics that are permanent - you have to prepare them yourself. The following Questions & Answers will help you decide what is best for your needs.
Q: What does “permanence” mean?
A: If a painting maintains its original appearance for 100 years without cracking, fading, sagging, and so on, it is considered permanent. If the canvas or panel that you paint on deteriorates, the painting itself will also suffer.
Q: Should I paint on a flexible or rigid support?
A: Oil paint becomes harder and more brittle with age and is therefore more prone to cracking. For this reason a rigid support is a good idea for oil paintings. Acrylics have not been around for hundreds of years like oils but scientific analysis and accelerated aging tests show that it will likely remain flexible indefinitely, like most plastics. For permanent results, acrylics can be painted on a rigid or flexible support, like canvas or paper. For sizes larger than about 20x30" rigid supports made of wood or wood fibers are quite heavy and more subject to warping. It is recommended that you glue a wooden frame (cradle) to the back of large panels to prevent warping.
Q: Do I need to size the canvas or panel before putting on the gesso ground?
A: Yes. Except for painting with acrylics on canvas or paper where it is not essential for permanence. Wood or wood products are acidic and the fibers will swell when a water based ground (gesso) or paint is used on them. A coat of sizing is designed to create an isolating barrier between the wood and the paint or ground and to regulate the absorbency of the wood. It is a good idea to put a coat on both sides. For any type of painting or collage on panel a thin coat of white shellac (diluted 3:1 with Methyl Hydrate) is a good size. You must be careful not to put it on too thick or the surface will become too smooth and the ground will not stick well. Oil Paints are also acidic and will cause canvas to deteriorate if it comes in contact with it. Here again the size acts as a protective barrier. The best material for sizing canvas for oil painting is hide glue. For Acrylics a coat of acrylic gloss medium is best and a coat on the back of cotton canvas will protect the fibers and make them less absorbent.
Q: Why is the ground important?
A: The ground, called a “Primer” for oil paintings, provides the ideal surface and absorbency for the paint to adhere to. The white surface of the ground ensures that the colors retain maximum luminosity as well. This is particularly important for oil paints which become darker and more transparent with age.
Q: Is acrylic polymer gesso a good ground for oil paintings?
A: It is difficult to say if the oil used to make the paints and the acrylic resin in the gesso will form a permanent bond since they are so different in their chemical and physical properties. When used on a rigid support like hardboard the oil paint will probably stay put. On canvas that moves it is more risky. Imagine how dried oil paint would react on a plastic bag that gets stretched. Because the acrylic gesso is more absorbent the oil in the paint seeps through to the canvas and will cause it to rot. The oil deprived paint also becomes more brittle and dull looking. This principle also applies to the common practice of painting in oils over an acrylic underpainting. For permanent painting on a flexible support the best choice for oils is linen canvas with the traditional hide-glue size and an oil based lead primer.
Q: What is the difference between the traditional gesso and the new acrylic polymer gesso?
A: For hundreds of years artists painted on panels using a simple gesso made of hide glue and calcium carbonate. It is the same hide glue used to make the size. This gesso is very absorbent and can be applied in very thin layers and sanded between coats to achieve a very smooth painting surface, more so than with acrylic gesso. The traditional gesso is very absorbent and needs to be sized before applying paint or it will absorb too much of the binder from the paint. The acrylic gesso substitute is made of acrylic polymer emulsion with calcium carbonate and some titanium dioxide and zinc oxide to make it whiter and give it more covering power.
Q: How about using Latex house paint as a ground instead of gesso?
A: This is acceptable for any painting that you don’t want to last. Artist’s materials are made with artists’ purposes in mind and for permanence. Industrial or commercial materials are made for other purposes and will have unpredictable results. Most house paint is specifically engineered to deteriorate within a few years so that is can be replaced.
Q: What is the difference between cotton and linen?
A: Unbleached cotton for artist’s canvas is a cream color and has little brown flecks in it. Linen is a darker brown, burlap colored fabric. Linen is a much more durable fabric for a couple of reasons. The fibers that make up the material are longer and rounded, unlike cotton fibers that are short and flat. Because the linen has linseed (flax) oil in the fibers, this gives it the dark color, the fabric is protected from pollutants and moisture in the air. Cotton is composed of unprotected cellulose fibers so it readily absorbs moisture from the air that causes it to expand and contract more than linen. This is not good for dried oil paint. The absorbent cotton canvas is more prone to deterioration from any substance that comes into contact with it, like acidic oils, sizes, or oxygen and pollutants in the air.
Q: Can I paint in acrylics on cotton and get permanent results?
A: Yes. Acrylic polymer mediums, paints, and gesso will even act as a plastic protection for the cotton canvas. Because acrylic paints remain flexible they will move with the canvas. A good practice is to coat the back of the cotton canvas with gloss medium to protect the fabric and make it less absorbent.
Q: What is the best product for a rigid support?
A: Untempered Hardboard. Masonite is a brand name commonly used to refer to this product. It is inexpensive, very durable and easy to work with. Hardboard is wood fibers compressed under pressure with the natural glue of the wood (lignin) serving as a binder to hold it together. When properly sized it is very permanent. The tempered hardboard has oil added to make it water-resistant so it not recommended for use as a support because the ground and paint layers will not adhere well to it. To prepare the hardboard panel, sand the smooth surface and put a thin layer of White Shellac on both sides. Then at least 2 layers of gesso on both sides. Other wood products like Chip Board and Melamine are heavy. Plywood is likely to warp, crack and separate as the glue between the layers dries out and all of these products are more expensive than hardboard. Hardboard panels are easy to ship and frame as well.
Q: How about a summary of some good choices for permanent painting?
A: For oils, acrylics, tempera paints, collage and mixed media, hardboard panels are excellent. Size them on both sides with White Shellac and at least two coats of gesso. In sizes up to about 16x20 1/8" hardboard is good unless you are doing very thick acrylic paintings or collages. 1/4" hardboard will be stable without warping too much up to about 20x30.” For oil painting 24x30 or larger linen canvas sized with hide-glue and coated on with a lead white ground on the front only is the best choice. For acrylics or mixed media on canvas, use cotton, linen or synthetic fabrics sized on both sides with acrylic gloss medium and gesso on the front.
