Artists' oil colours are put together by mixing dry powder pigments with selected refined linseed oil until the substance reaches a stiff paste consistency and grinding it by strong friction in steel roller mills. The smoothness of the hue is fundamental. The common standard is a smooth, buttery paste, rather than stringy or long or tacky. When a flowing or mobile aspect is desired by the artist, a liquid painting medium like pure gum turpentine needs to be added with it. To speed up drying, a siccative, or liquid drier, could be sometimes used. Top-class brushes are produced in two types: red sable (with hair from different members of the weasel family) and chemically whitened hog bristles. Both can be purchased in numbered sizes for four regular shapes: round (pointed), flat, bright (flat shape but shorter and not as supple), and oval (flat but bluntly pointed). Red sable brushes are generally preferred for a smoother, delicate kind of brushstroking. The painting knife, a declicately tempered, limber version of the palette knife, is a convenient utensil for using oil colours in a robust manner. The usual support for oil paintings is a canvas of pure European linen of sturdy close weave. This canvas is cut to the required size and stretched over a frame, commonly wooden, to which it is secured with tacks or, in the 20th century, by staples. To lower the absorbency of the fabric itself and to achieve a smooth surface, a primer or ground might be applied and allowed to dry before painting begins. The most generally used primers have been gesso, rabbit-skin glue, and lead white. If density and consistency are preferred rather than springiness and texture, a wooden or processed paperboard panel, sized or primed, might be utilised. Many other supports, like paper and different textiles and metals, have been experimented with. A polish of paint varnish is often put on to a completed oil painting to protect it from atmospheric attacks, minor abrasions, or injurious accumulation of dirt. This varnish might be taken off without damage by experts with isopropyl alcohol and other household solvents. The painting varnish also takes the surface to a consistent lustre and takes the depth of tone and colour intensity really to the levels originally formed by the artist in the wet paint. Some modern painters, particularly those who do not favour deep, intense colouring, keeping a mat, or lustreless, finish in their oil paintings. Most oil paintings from previous to the 19th century were done in layers. The first layer was a blank, uniform field of thinned paint known as a ground. The ground lessened the gleam of the primer and formed a gentle colour base on which to build images. The shapes and objects in the painting would be roughly blocked in by using shades of white, as well as gray or neutral green, red, or brown. The resulting field of monochromatic shades were termed the underpainting. Forms would be further defined with either ordinary paint or scumbles; irregular, thinly applied layers of opaque pigment that imparts a variety of visual effects. For the last point, transparent layers of pure colour known as glazes were used to display luminosity, depth, and brilliance to the objects, and highlights could be imparted with thick, textured patches of paint known as impastos. Oil as a medium of painting is chronologised back to the 11th century. The technique of easel painting with oil colours, however, stems directly from 15th-century tempera-painting methods. Basic improvements in refining linseed oil and the availability of volatile solvents after 1400 coincided with a requirement for some medium other than pure egg-yolk tempera, meeting the developing desires of the Renaissance (see tempera painting). Initially, oil paints and varnishes would be utilised to glaze tempera panelswhich had been painted from the typical linear draftsmanship. The technically gleaming, crystal-like paintings of the 15th-century Flemish artist Jan van Eyck, for example, were perfected in this new style. In the 16th century, oil colour became established as the basic painting material in Venice. At the end of the century, Venetian artists had grown proficient in exploiting the essential characteristics of oil painting, particularly in their employment of successive layers of glazing. Canvas, after a long time of growth, replaced wood panels as the most commonly used support. One of the 17th-century masters of the oil technique was Vel?zquez, a Spanish artist in the Venetian tradition, whose supremely economical but sure brushstrokes have frequently been copied, notably in portraiture. The Flemish painter Peter Paul Rubens challenged the norm in the style in which he loaded the light colours opaquely, in juxtaposition to his thin, transparent darks and shadows. Another great 17th-century master of oil painting was the Dutch painter Rembrandt. In his art, a single brushstroke would effectively depict form; cumulative strokes give great textural depth, with a combination of the rough and the smooth, the thick and the thin. A field of loaded whites and transparent darks is finally enhanced by glaze, blendings, and highly controlled impastos. Other particular influences on the techniques of later easel painting are the smooth, thinly painted, deliberately planned, tight appearances. A great many admired works (e.g., like those of Johannes Vermeer) were executed with smooth and graduated blends of shades to create subtly modeled forms and delicate colour variations. The technical requirements of some schools of modern painting cannot be realized by traditional genres and techniques, however. Many abstract painters - as well as to some extent modern painters who use these traditional styles - have demonstrated a need for a plastic flow or viscosity that cannot be formed from oil paint and its conventional additives. Some desire a larger variation of thick or thin applications and a speedier rate of drying. Some have mixed coarsely grained substances with their colours to create texture, some of them used oil paints in much greater volume than usual, and a large part have started to use acrylic paints, as they are more versatile and dry quickly.Interested in oil painting? For art supplies Brisbane, including canvas art supplies and artists supplies, visit or call the Discount Art Warehouse.