Oil on canvas; tempera on panel; watercolor on paper. Those and similar phrases are on the labels of nearly any painting in a museum or art gallery. Different painting mediums yield different visual effects because of the paint's overall properties and because of how the paint works with the surface being painted. Whether of completely natural or man-made ingredients, all painting mediums are composed of pigments (color) added to a vehicle (or base).
Acrylic paints are a combination of pigments added to an acrylic resin solution. Pliable and easy to work with, acrylics offer brilliant hues and quick drying times. First developed in the 1940s, today's acrylic paints are water-soluble. They are among the more-frequently used artist's painting mediums and, for many artists, are an alternative to the slower-drying medium of oil.
Enamel paints are most often oil- , latex- or water-based paints with varnish added to them. In use since the 1930s, enamels can be applied by traditional fine-art utensils, spray can or air brush. Used for painting such objects as porcelains and cars, enamels are prized for their ultra-glossy appearance and finish.
Used most often in the Middle East and Northern Africa, encaustic is an ancient practice that combines pigments with a hot wax such as beeswax. Encaustic artists apply the paint to a prepared surface of panel or canvas. Unlike other mediums, encaustic does not yellow over time and temperature changes and moisture do not significantly affect it.
If you've ever taken an art history class, the term "fresco" might seem familiar. Used widely during the height Italian Renaissance by such painters as Giotto, Raphael and Michelangelo, fresco is a sensitive and painstaking medium. Meaning "fresh" in Italian, fresco is the process of painting images directly into the wet plaster on walls. In true fresco, or buon fresco, pigments (often of tempera) are applied to small working sections of wet plaster. Once dry, the pigments become a permanent part of the wall. Noted examples of fresco include Giotto's Arena Chapel, Raphael's Stanze at the Vatican and Michelangelo's Sistine Ceiling.
For most people, painting with latex paint involves brushes, rollers and moving furniture. While it is the preferred medium for painting building interiors and exteriors, this water-soluble medium is also good for such artistic applications as murals. Don't confuse the latex paint used for house painting with Liquid Latex, however. Liquid Latex has a higher rubber content than house paint and is suitable for deliberately placing on the skin. Modern latex house paint, while non-toxic and safe for skin contact, contains polymers and little to no rubber, despite its given name.
Oil Paint & Alkyds
Used widely since the 15th century, oil paint is perhaps the most used medium. It's made from combining pigments to such oils as linseed, flax, hemp or nut. Oil paints are quite pliable and allow artists to work with quick or broad brushstrokes and even build up layers of paint. The properties of the oil allow for a rich, bright finish even when dry. Rembrandt is one artist known for his mastery of the medium.
Modern and contemporary artists often use alkyds--a synthetic cousin of the traditional oil paint. Alkyds are a mixture of pigments and an alkyd base that is composed of a synthetic resin made of oil-modified poylesthers (polybasic acids) and a polyhydric alcohol such as glycerin. Alkyd is prized for its quick drying time and, for some artists, superior workability to traditional oil paints.
Most people are probably familiar with tempera, and may not even realize it. If you went to kindergarten in the United States, chances are excellent that you have used it for finger painting and crafts. In its truest form, tempera paint is made by adding pigments ground to a fine powder with egg yolks and mixed to a uniform color. Most commercially-made tempera paint is composed of various non-toxic and water-soluble chemicals. Tempera paint is bold, adheres well to nearly any surface and is nearly permanent once dry.
Quite probably the oldest painting medium, pigments added to water create watercolor paint. Known for its transparency, watercolor layers well and the ratio of water to pigment modifies color intensity. It is not an easy technique to master, as it can be difficult to overcome its aqueous--and sometimes runny--nature. Modern watercolors contain some additives to ease work and watercolor's cousin, gouache, includes chalk to create a more opaque consistency.