Materials and Supports

Supports
In painting, canvas is still the most widely used foundation or support. Stretched-and-primed canvas is taut but flexible, and has a unique receptiveness to the stroke of the brush. The two most common fibers for making canvas are linen and cotton. Each of these fibers can be founding a range of durability, evenness of grain, ease of stretching, and costs.
Cotton Duck is the popular, inexpensive support. It is made of cotton fibers and comes in a many densities/textures.
Linen is a more long lasting support and also comes in a range of densities and textures. Artists often prefer the tooth of the linen canvas. However, it is expensive and sizing and a primer are recommended.
Canvas Boards are pulp cardboard covered with acrylic gesso and tend to be inexpensive but not very durable and may warp, especially in sizes larger than 9x12”.
Prestretched Canvas is created from cotton duct canvas (usually of a light weight ≤ 9 oz) wrapped over pine stretcher bars and primed with acrylic gesso by the manufacturer.
Paper or Cardboard can be lightweight and fast supports once they are sized.
Wood Panel was the traditional support for painting for centuries, but now warping is an issue for untreated wood. It is also heavy, but provides a stiff support.
Masonite is inexpensive, fairly strong, and lightweight. The tempered variety is necessary for painting but it still needs to be sized. It is prone to warping, but priming the back of the board can reduce this risk.
Metal can be used as a stiff support. Artists have historically used copper for coloristic qualities, but contemporary artists also use aluminum and others.

Sizing seals porous fabric and isolates it from ground or paints. Otherwise the oil paint will rot the support. Rabbitskin glue made from animal hide is the traditional size.
Grounds or primers provide a strong foundation upon which to build up a painting. The traditional, and best, primer for oil painting is oil-based lead white, which can be made from flake-white.
Acrylic Gesso is an acrylic primer is flexible, durable, water-thinnable, fast drying and inexpensive. It can be used to prime canvas, board, paper, and other surfaces and can be applied directly to the support without the need of an isolating layer of size. The term is confusing because it is not a gesso at all: traditional gesso is prepared with animal glue and chalk, and is very absorbent.

Other Materials
Palette Knives are used for mixing colors on the palette, scraping palettes clean, and for scraping into or adding wet paint on the surface of the picture. They have a straight, flat, flexible blade with a rounded tip.
Palettes come in a variety of shapes, sizes, and materials designed to suit the artist’s individual requirements. A larger palette is better than a smaller one, because you need space for mixing variations of color. 14x18” is a good size. Materials can include glass, plexiglass, disposable tear away sheets, and wood. Wood panels must be treated with linseed oil before use but establish a middle tone upon which to base paint values.
Solvents are used to thin oil paint, for cleaning purposes, and for mixing mediums. The traditional solvent is pure turpentine, which dries without leaving any residue. However, it is extremely unstable, flammable, and toxic. Substitutes such as turpenoid or mineral spirits are slightly less dangerous but still very harmful and can be absorbed through the air, skin, or ingested. Environment friendly paint thinners are poor substitutes for these other solvents. Proper ventilation is necessary when using solvents as well as proper disposal of liquids or rags in fire-proof bins.
Mediums are variously formulated to improve the flow of paint, alter its consistency, and produce either a matte or a gloss finish. Some increase drying time while others speed it up. Many manufactured mediums exist but artists can mix their own mediums. For oil, Liquin and Galkyd improve the flow and transparency of oil paint while speeding up the drying time. For acrylic, an even greater range is available.

Recommended reading
The Artist's Handbook of Materials and Techniques by Ralph Mayer is considered the bible among art handbooks. It contains detailed, formulaic explanation of materials and processes but tends to be a little dry.