Mastering Impasto Mediums: Techniques for Oil Painting

Impasto mediums for oil painting consist of oil, sometimes resin, and an extender pigment. Extender pigments are white inorganic minerals that essentially become transparent when added to oil paint.

Impasto mediums, or paste mediums, are ideal for thickening oil paints. One benefit of using impasto mediums is that they dry evenly without cracking or wrinkling.

Most artists do not know that paste mediums are also the best for glazing. They do not increase the drying time of oil paint, as do most glazing mediums or oil. Because they contain extender pigments, they do not increase the ‘fat’ of the oil paint layer.

Oil makes a slow-drying paint consisting of pigments in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by adding a solvent, such as turpentine or mineral spirits (white spirits), and alkyd to increase the glossiness of the dried film.

What is the appearance of impasto mediums when dried?

Impasto mediums dry to a satin or matte sheen like most oil paint when used in recommended amounts.

What is the recommended ratio of oil paint to impasto medium that can be used safely?

Impasto mediums have a high pigment load, so apply them to your painting the same way you would oil colors. Since they are both essentially oil paints without driers, solvents, and resins, no reasonable maximum amount of paste mediums can be used. However, because they are essentially colorless, as the oil yellows and darkens, they should not be used alone, and depending upon the color mixed with them, a sufficient amount of oil color must be added.