Artists’ oil colours are made by stirring dry powder pigments with special refined linseed oil until the mixture reaches a stiff paste consistency and then grinding it under powerful friction in steel roller mills. The smoothness of the colour is important. The common standard is a smooth, buttery paste, rather than stringy or long or tacky. When a more flowing or mobile quality is required by the artist, a liquid painting medium such as pure gum turpentine has to be added with the mixture. To accelerate drying, a siccative, or liquid drier, should be occasionally used.
Top-class brushes are sold in two kinds: red sable (hair from varying members of weasel) and chemically whitened hog bristles. They are available in numbered sizes for the four regular shapes: round (pointed), flat, bright (flat shape but is shorter and less supple), and oval (flat but bluntly pointed). Red sable brushes are widely utilised for a smoother, more delicate kind of painting. The painting knife, a thinly tempered, thin version of an art palette knife, is a common item for using oil colours in a robust manner.
The common support for oil paintings is a canvas manufactured of pure European linen of stable close weave. This canvas is cut to the desired size and cast over a frame, mostly wooden, to which it is then secured by use of tacks or, since the 20th century, with staples. If the artist desires to reduce the absorbency of the fabric itself and achieve a smooth surface, a primer or ground may be applied and left to dry first. The most often employed primers have been gesso, rabbit-skin glue, and lead white. If rigidity and smoothness are preferred over elasticity and texture, a wooden or processed paperboard panel, sized or primed, can be utilised. A number of other supports, like paper and some textiles and metals, have also been experimented with.
A layer of picture varnish is commonly set on to a completed oil painting to protect it and prevent atmospheric attacks, minor abrasions, and injurious accumulation of dirt. This film of picture varnish may be taken off without damage by experts with isopropyl alcohol and other such household solvents. Varnishing also sets the surface to a consistent lustre and sets the depth of tone and colour intensity virtually to the look initially formed by the artist in wet paint. Some modern painters, in particular those who do not favour deep, intense colouring, and prefer a mat, or lustreless, finish in their paintings.
Most oil paintings dating before the 19th century were built up in layers. The first would be a blank, uniform field of thin paint called a ground. The ground graduated the white gleam of the primer and established a base of gentle colour on which to build images. The shapes and items in the painting would then be roughly blocked in with shades of white, along with gray or neutral green, red, or brown. The eventuating field of monochromatic light and dark were known as the underpainting. Forms would then be defined with either solid paint or scumbles; non-uniform, thinly applied layers of opaque pigment that imparts a range of effects. In the last stage, transparent layers of pure colour known as a glaze then would be employed to display luminosity, depth, and brilliance to the objects, and highlights could be defined with thick, textured patches of paint known as impastos.
Oil as a painting medium is recorded as early as the 11th century. The technique of easel painting with oil colours, however, came directly from 15th-century tempera-painting styles. Essential improvements in refining linseed oil and the availability of volatile solvents after 1400 coincided with a need for some medium other than pure egg-yolk tempera, in meeting the contemporary requirements of the Renaissance (see tempera painting). At first, oil paints and varnishes had been utilised to glaze tempera panels, painted with their usual linear draftsmanship. The technically brilliant, crystal-like portraits from the 15th-century Flemish painter Jan van Eyck, for example, were perfected in this new style.
In the 16th century, oil paint became established as the basic painting material in Venice. At the beginning of the 17th century, Venetian artists had grown proficient in the exploitation of the essential characteristics of oil painting, notably in their employment of many layers of glazing. Canvas, after a long period of growth, replaced wood panelling as the most popular support.
A 17th-century master of the oil technique was Velazquez, a Spanish painter in the Venetian tradition, whose highly economical but informative brushstrokes have frequently been emulated, particularly in portraiture. The Flemish painter Peter Paul Rubens challenged tradition in the style in which he loaded the light colours opaquely, to juxtapose the thin, transparent darks and shadows. Another notable 17th-century master of oil painting was the Dutch painter Rembrandt. In his work, a single brushstroke can effectively depict form; cumulative strokes created great textural depth, by combining the rough and the smooth, the thick and the thin. A technique of loaded whites and transparent darks was finally enhanced by glazed effects, blendings, and highly controlled impastos.
Other notable influences on the later easel painting techniques are the smooth, thinly painted, deliberately planned, tight appearances. A great many admired works (e.g., from Johannes Vermeer) were completed with smooth graduated blends of shades to achieve shadowy forms and delicate colour variations.
The technical requirements of some schools of modern painting cannot be attained with traditional genres and/or techniques, however, and many abstract painters – including to some extent contemporary traditionally-geared painters – have demonstrated a desire for a plastic flow or viscosity that cannot be formed in oil paint and its conventional additives. Some require a wider range of thick to thin applications and a speedier rate of drying. Some artists mix coarsely grained substances with colours to create texture, some of them apply oil paints in greater volume than usual, and many have begun using acrylic paints, because they are more versatile and dry speedily.
Interested in oil painting? For art supplies Brisbane, including canvas art supplies and artists supplies, visit or call the Discount Art Warehouse.