Oil painting is one of the world's most popular artistic mediums due to its flexibility in working methods and applications as well as its durability. Pigment is dispersed in a drying oil, such as linseed, safflower or walnut, and applied to a prepared surface in one of numerous methods. Artists working in oil paint can achieve various effects in their work through the use of methodical, as well as quick and expressive, painting techniques.
Glazing is an oil painting technique where multiple thin, transparent layers of pigment are applied successively to create color, shading and form. The glazes are prepared from oil paint mixed with a large amount of medium, such as linseed oil and varnish, sometimes with a drying agent added. Typically, the glazing layers are painted over a highly refined charcoal drawing or a monochrome underpainting. Developed by Flemish artists in the early Renaissance, this approach to oil painting results in vivid, jewel-like colors and startling realism.
The impasto technique takes the opposite approach to oil painting as glazing. For impasto painting, color is applied thickly with a heavily loaded brush, such that the painting surface retains the shape and expression of every brushstroke. The viscous quality of oil paint makes it suitable for this technique, where paint is typically applied directly from the tube with the use of little if any medium. Impasto paintings can have a strong sense of immediacy and emotional character.
Alla prima is also known as direct painting and refers to a painting completed in one session while the paint remains wet on the canvas. Colors in alla prima painting retain a freshness although it is difficult to achieve the degree of detail and realism possible with glazing and layered approaches. Oil paint is ideal for alla prima work because of its typical slow drying time, allowing an artist to work the paint for several hours or even days before becoming too dry to manipulate.
Sgraffito is a traditional technique of drawing in a wet layer of oil paint to reveal either bare canvas or an earlier layer of paint below. A painting knife, pencil or other tool can be used to create detailed line work or patterned effects. The slow drying time of oil paint again makes this approach possible as an artist has the time to work methodically and carefully to produce detailed line drawings.
Knife painting is similar to impasto except that a painting knife is used to apply the oil paint instead of a brush. A painting knife produces expressive textural effects as it can be held in many different ways, horizontally and vertically, and create both bold and lighter strokes. Knife painting can give an oil painting a nearly three-dimensional appearance and is generally completed with wet-into-wet opaque paints.