Pigments and mediums
Oil paint is pigment suspended in oil, usually linseed oil. Painters thin oil paints by adding either more oil or a solvent, such as turpentine--or a mixture of both.
In addition to linseed, artists use walnut, poppy seed, and safflower oils when painting. Each has its merits, and artists hold different opinions on which oil is preferable. For example, many painters swear by walnut oil, but it is expensive, and others assert that poppy seed oil dries with the least yellowing. Linseed is the most common oil, but it is known to yellow noticeably as a painting ages.
In addition to turpentine, artists use mineral spirits and Turpenoid. Turpentine is made from a tree resin; mineral spirits and Turpenoid are petroleum products.
Other mediums used by painters include varnishes and resins. These mediums give paint a jewellike shine, allow for easy glazing of color layers, and protect the finished painting by acting as a hard shell.
Paintbrushes generally fall into two categories: soft-hair and bristle. Both categories feature natural hair or synthetic fibers.
Soft-hair brushes, which can be made from synthetic fibers, sables, squirrels, or oxen, allow smooth strokes and delicate marks. They are ideal for watercolor painting because they can hold a larger amount of thin paint. Bristle brushes, which are sometimes made with hog’s hair, are for scrubbing in a color or quickly blocking in an underpainting--or for adding texture to a piece. They are also useful for applying thick paint, and watercolorists occasionally use them to pull pigment off a surface.
|A variety of bristle brushes. Left to right: fan blender, round, bright, filbert, and flat.
Brushes come in several shapes. Rounds feature a cylinder of hair that usually comes to a point. Filberts are flat brushes with a rounded tip. Flats are flat brushes with sharp corners.
Artists also regularly use palette knives for moving paint around on the surface, sculpting edges in the paint, creating large, flat planes of thick paint, and applying large amounts of paint for highlights. The palette knife is also used to mix colors on the palette.
One chooses the appropriate canvas by considering the texture desired for the composition and the amount of money one wishes to spend. Canvas is primarily made from either linen fibers or cotton. Two examples: Portrait linen is very smooth--and expensive. Cotton duck has more texture and is more affordable.
Canvas can be purchased in a roll or prestretched over a frame. It can be bought primed with gesso or in its raw state. If canvas isn’t primed, the paint will bleed into adjacent areas, plus the archival quality of the canvas will be compromised. Artists can save money by stretching canvas themselves.
Bob Bahr is the managing editor of American Artist.