Oil Painting - Characteristics

Appearance Although earlier painting methods allowed artists to produce some opaque and transparent effects, oil technique permits painters still greater richness in these regards. Opaque passages can be thicker without a risk of cracking, and transparent effects can be controlled more easily since the thinned paint remains wet for a longer time. The resulting range of contrasts between transparent shadow and opaque light can develop a striking variety..... By applying transparent deep colors over opaque tones, the painter can produce rich modulations of darks and can give the picture a tonal depth not available in most other techniques. [pp. 55-56.]

Drying Qualities Because strokes of oil paint dry more slowly, they can be easily blended with each other, providing a softer merging of one tone into the next [and, increasing the medium, the oil and turpentine, one can work in a wet on wet manner creating great luminosity and color transparency.] The subtle changes of light in a Van Eyck interior or in a Giovanni Bellini portrait indicate that fifteenth century artists made enthusiastic use of this quality of the oil medium to produce a controlled softness of blended tones that was not usual in the egg tempera technique as it was then practiced.

As the paint stays wet for a long time, the artist can wipe out mistakes with a rag or scrape them away with a painting knife more easily and selectively. Painters can make many corrections and still keep the canvas looking fresh.

Since the oil medium remains workable longer, painters can mix exact color nuances on their palettes with greater thoughtfulness and precision than was allowed by the faster drying paints. Furthermore, the appearance of oil paint, when it is used with the appropriate painting medium, remains virtually unaltered as it dries, whereas fresco, tempera, and water paints tend to change tone during the drying process, making the judgment of color more difficult for the artist. The nature of their drying process makes oil paints more portable and convenient to use, both in the studio and for landscape and other motifs outside the studio, since, in contrast with the fast-drying fresco, tempera, and encaustic colors, oil paints can be ground and stored ready to use in containers for longer periods of time. [p. 55]

Film Quality The film flexibility of oil paint has several consequences. Oil paint can be used on flexible supports such as canvas, whereas the more brittle films of the older paints require a rigid support, such as a wood panel or a plaster wall. As canvas can be manufactured in larger sizes than wood panels, it became possible to produce oil paintings in larger formats than those that had been usual when tempera or encaustic was employed.

Because of the oil's flexibility, heavier applications of oil paint do not crack, as do egg tempera or distemper colors. Therefore a greater range of textural effects, from thick to thin and from rough to smooth, becomes possible in the oil technique.

The film flexibility of oil paint allows the building up of layers of paint, one over the other, permitting the artist to paint over parts of the picture, adding further subtlety or unifying the disparate elements in the painting. Oil paintings can become more complex than can pictures painted in older techniques, as the artist adds layer on layer of compositional modification.

Oil paint dries to a tougher, more scratch-resistant film than does egg tempera, distemper, or encaustic, and it is less likely to be damaged by water or moisture than is egg tempera, distemper painting, watercolor, or pastel. [p. 55]

Disadvantages Some of the disadvantages associated with oil painting should be mentioned here. Some painters require a paint that sets faster than oil paint does because they like to work over a dry underpainting with a rapid sequence of washes or overpaintings. For them the slow drying of oil paint is a disadvantage, and they turn to other media. In other cases, relying on the oil medium's latitude for repainting, an indecisive artist may postpone the solution of major problems in the picture's composition and drawing, causing the work to suffer from a lack of clarity and from insufficient firmness of expression. Similarly the ease with which oil paint can be blended sometimes encourages a soft muddy effect and a lack of clear color and shape definition. Finally, linseed oil paint films do become somewhat yellow and darker as they age, although the use of good materials and sound technique can reduce this darkening to a point at which it is scarcely noticeable. Many oil paintings by the old masters retain a high quality of chromatic and tonal intensity after more than four hundred years. [p. 56]

[Kay, Reed. The Painter's Guide to Studio Methods and Materials. Englewood Cliffs, NJ: Prentice-Hall, Inc., 1983.]

Pentimento
The technical term pentimento refers to a peculiar effect, examples of which are to be seen in galleries, where, because thin top coatings of paint have become more transparent with age, the underpainting or drawing originally concealed has become visible. Notable or striking examples of pentimento are seen in some of the works of De Hooch, where the bold black-and-white checkerboard of floor tiles occasionally shows through the figures and furnishings in the room. They are found also in early Italian paintings where the architectural lines of buildings may sometimes be discerned running through the figures that have been superimposed on them. Such effects also are commonly seen in more recent pictures where the artist has made changes during the painting and, in [p. 116] obliterating unwanted brushwork or altering contours by overpainting, has been so careless in making these changes that, on relatively short aging, the colors underneath have become visible or the texture of underlying brushstrokes has become more pronounced. Although it may take such notable examples to bring home the fact that paint is likely to become literally transparent with the years--because of the increase of the refractive index of linseed oil film with age or for other reasons--the general effect of transparency exists in all old paints. The lessons that careful painters have learned from this are several: that multiple layers of paint must be planned with this effect in mind; that when underpainting is to be concealed or obliterated, the top coat must be sufficiently opaque for the purpose; that distinctly dark or outstanding areas should be scraped away before overpainting them with paler tones; and that disturbing textures and brushstrokes should be taken down, using a sharp blade if the paint is too hard to be cut with a paletteknife. The underpainting and the ground will always have some degree of influence on the final painting except when the paint is applied in an extremely thick impasto layer. [pp. 115-116]