OIL PAINTING
WHILE THE HISTORY of paints made from vegetable drying oils goes back to the Middle Ages and oil paints were known to painters of the fourteenth century and earlier, they were not widely adopted for use in easel painting until the fifteenth century. By the middle of the sixteenth century, the method was in full swing in a rather well-developed form, and ever since, oil painting on canvas has remained the standard technique for artists' easel painting.
Although all the other techniques are practiced for certain advantages they have over oil painting, the latter remains standard because the majority of painters consider that its advantages outweigh its defects and that in scope and variations of optical quality it surpasses watercolor, tempera, fresco, acrylic, and pastel.
From the viewpoint of permanence, however, the accepted and time-tested methods of painting may be considered to be of equal merit. They all possess certain inherent defects which the careful painter does the utmost to minimize, and each presents peculiar difficulties which can be overcome. Materials for each must be carefully selected; oil paint, tempera, and fresco must be correctly manipulated and applied if they are not to deteriorate; and the fragility of watercolors and pastels requires that they be carefully preserved. Although the newer synthetic resin paints, such as acrylic polymer, have not stood the test of time, they may prove to be extremely permanent paint mediums.
In the past, oil painting dominated the field to such an extent that from the standpoint of public acceptance, the other methods of painting relegated to the status of minor techniques. With the development of art., especially in modern practice with so many facets of art being appreciated in the same era, there is now not so wide a gulf between the leadership of oil painting and the secondary use of other techniques, and many of our greatly admired artists create their major works in techniques other than oil.
The basic points of the oil technique's superiority over the other accepted methods of permanent painting are:
Its great flexibility and ease of manipulation, and the wide range of varied effects that can be produced.
The artist's freedom to combine transparent and opaque effects, glaze and body color, in full range in the same painting.
The fact that the colors do not change to any great extent on drying; the color the artist puts down is, with very slight variation, the color he or she wants.
The dispatch with which a number of effects can be obtained by a direct. simple technique.
The fact that large pictures may be done on lightweight, easily transportable linen canvases.
The universal acceptance of oil painting by artists and the public, which has resulted in a universal availability of supplies, refined, developed, and standardized.
Its principal defects are the eventual darkening or yellowing of the oil, and the possible disintegration of the paint film by cracking, flaking off, etc. The former may be eliminated or reduced to an acceptable minimum by correct selection and use of the highest quality materials, and the latter by correct handling of the technique.
PAINT
Paint consists of finely divided pigment particles evenly dispersed in a liquid medium or vehicle; it has the property of drying to form a continuous, adherent film when applied to a surface for decorative or protective purposes.
The surfaces any be colord or decorated by applying the pigment directly in pasted painting the protective function may be applied by a fixative, the application of which is separate from the decorative color application and in fresco the ground itself applies the adhesive or binding property.
However, paint, in the commonly accepted meaning of the term, usually implies a material that combines these functions as typical oil or tempera paint.
When drying oil is used as a medium for painting, it performs the following:
- Executive. It allows the colors to be applied and spread out.
- Binding. It locks the pigment particles into a film, protecting them from Atmosphere or accidental mechanical forces and from being disturbed by the application of subsequent coats of paint.
- Adhesive. It dries and acts as an adhesive, attaching the colors to the ground.
DRYING OILS
A number of vegetable oils have the property of drying to form tough, adhesive films either by themselves or when assisted by the action of added ingredients. These oils do not “dry up” in the ordinary sense of the evaporation of a volatile ingredient, but they dry by oxidation or absorption of oxygen from the air. The drying process is accompanied by a series of other complex chemical reactions, and the dried oil film is a new substance which differs in physical and chemical properties from the original liquid oil; it is a dry, solid material that cannot be brought back to its original state by any means.
The increase in weight or volume of the oil through the absorption of oxygen is compensated for to a variable degree by the loss caused by the passing off in gaseous form of certain by-products of the reaction. These changes may be measured in the laboratory and from such figures we gain considerable knowledge of the properties of our oils.