Alkyd Resin Medium

Some products [Win-Gel, Oleopasto impasto medium, and Liquin oil-painting medium, made by Winsor and Newton, Ltd., London, New York, Sydney.] containing oil-modified alkyd resins compounded for artists' use as oil paint mediums have appeared on the market. These are in the form of either liquid mediums or gels which are added to oil colors to impart their brushing quality to the paint. These media tend to allow fluid handling when they are mixed or brushed out, but when left undisturbed they thicken and gel quickly. This quality, called a thixotropic effect, allows some handling and brushing qualities not easily obtainable in other media. These alkyd additions also accelerate the drying of oil colors.

In 1976 artists' paints ground in the alkyd medium were put on the market by Winsor and Newton Company. The list of colors contains 24 standard pigments and 6 new synthetic pigments, rated as having class A permanence. The painter can thin the colors with turpentine or mineral spirits in the same way that standard linseed oil colors are diluted, or the artist can alter their brushing quality by adding one of the alkyd liquid or gel painting mediums mentioned before. The alkyd paints are compatible with other oil painting mediums made of oils, resins, and turpentine or mineral spirits. Although the Winsor and Newton alkyd colors come from the tube in a consistency that is quite stiff, the Winsor and Newton London Alkyd colors are of a softer consistency, and they dry a little more slowly than do the other alkyds. [p. 199]

The colors set more quickly than do linseed oil paints, drying to a tacky surface within 4 hours and becoming dry to the touch within 8 hours. Most layers of average thickness will dry to a solid film within 18 hours and can be safely painted over on the next day. An interesting aspect of the alkyd paint's film-forming characteristics is that the paint dries throughout the paint film, rather than skinning over at the top of the film as linseed oil colors do while remaining soft underneath.

Alkyd paints behave very similarly to linseed oil colors that have had a percentage of resin added to the medium. They hold the stroke well, build up impasto effects easily, and provide effects of wash or glaze with great fluidity. All the alkyd colors take approximately the same time to dry. The surface of the dried film has a soft, even shine.

Compared to the water techniques, alkyd paints allow more fusion of strokes than do such paints as egg tempera, gouache, distemper, or acrylic emulsions. The alkyd paint remains wet longer than the water-thinned paints, can be altered or painted into easily, and permits a wide variety of calligraphic possibilities. Because the alkyd paint remains wet on the palette, the artist can make tonal and chromatic mixtures of color with the great precision and ease that is one of the principal advantages of the oil technique.

After the alkyd paint film has dried for more than a day, it is not easily dissolved by turpentine or mineral spirits. In this regard it differs from the acrylic solution paints, which remain soluble in turpentine no matter how long they have dried. No isolating varnish is necessary between layers of alkyd paint to prevent the turpentine in the overpainting from disturbing or picking up the underpainting. [pp. 199-200]

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