A traditional oil painting is created in layers from the raw canvas to the final highlights. While newer materials (including acrylic gesso) have shortened the steps for many artists, some still prefer the time honored way of creating an oil painting that will survive the centuries.

1. The canvas, stretched over wooden supports, is traditionally a heavy linen or cotton. Heavy linen canvas has been in use for centuries as a painting support. The tightness of the weave will determine the smoothness of the surface. The canvas is stretched evenly around well squared wood stretcher bars and attached with brads or staples . Solid boards or panels are also traditional surfaces but the subsequent painting layers are the same.

2. The raw canvas is sealed with a sizing made of rabbit skin glue. The glue comes in a granular form and must be carefully dissolved in hot water. (The sizing has a quite unpleasant odor.) After disolving, the glue is allowed to cool and form a jelly after which the strength of adhesion is tested. The size is then reheated slightly and painted on the canvas while warm. The glue sizing makes the canvas less absorbent by sealing the pores between fibers.

3. Priming, also known as ground, is traditionally a lead white paint that is the base for the painting. (Lead bearing paint is dangerous and must be used very carefully) The ground must be absorbent enough to provide a ‘tooth’ for the paint, so that the paint adheres well but not too much that it drains oil away from the surface and cause dull spots in the painting. The artist may use several layers of priming, sanded between layers for a smooth painting surface (for portraits).

4. A toned ground is a stain over the white priming. This provides the artist with a warmer color under the painting and sets the tone for the painting. The stain is usually a diluted earth color such as raw sienna or burnt umber thinned with turpentine. A transparent ground is called imprimatura and allows light to reflect through paint layers making for more luminous colors in the finished painting. A toned ground must be very dry before painting over it.

5. The underpainting is a toned drawing in oil that is the beginning of the painting itself. The artist uses an underpainting to develop the relationships of dark and light in the composition and balance warm and cool areas. Sometimes the colors used are unrealistically intense in order to influence the colors of the next layers. This is especially true when the artist is painting in transparent layers (glazing). These first steps are painted with colors thinned with turpentine.

6. The artist continues to build on the underpainting in subsequent layers to complete the painting. Renaissance artists used thin layers of transparent colors carefully layered to build luminous color effects. Each layer will have a little more oil in the paint mixture so that the painting will not crack as it dries.

7. When the painting is finished and has dried at least six months, the artist will protect the surface of the painting with damar varnish in two thin coats. This layer of varnish can be removed years later when the surface needs to be cleaned.