Permanence of Oil Paints

(Excerpts from ART HARDWARE: The Definitive Guide to Artists’ Materials, by Steven Saitzyk © 1987 revised 1998)

The whole idea of permanence raises as many philosophical issues as it does practical matters.  Philosophically, the only thing that is permanent is impermanence.  Practically speaking permanence is relative.  One thing can only be more or less permanent than another.  By this standard, oil paints, when used as designed, is an extraordinarily permanent medium.  It weaknesses lay in the area of the lightfastness and compatibility of the pigments, which is discussed extensively in the chapter on pigments, and the maintenance of the protective coating that each particle of pigment possesses to prevent chemical interaction between pigments.  It could be argued that oil colors are not permanent because as oil ages it tends to darken and yellow, particularly if it is comprised primarily of linseed oil.  However, there are few things in this world that could last several hundred years without a small shift in color.

The permanence of oil paint is also affected by atmospheric pollution, such as the sulfur dioxide and hydrogen sulfide present in city air.  Unprotected (unvarnished) metal‑based paints like the chrome colors, such as chrome yellow, and chrome green, white lead, cremnitz white, cinnabar green, as well as colors like ultramarine blue and permanent blue, can discolor when they come in contact with these acidic pollutants.

Such colors as alizarin crimson, brown madder alizarin, indigo, permanent green, and purple madder alizarin are not as permanent when used in thin glazes.  BON arylamide and arylamide yellow commonly used to make colors like Scarlet lake and various shades of orange are particularly sensitive to pale tints with white.  Mixing white, or any color of greater permanency, with colors of lesser permanency does not improve the permanency of the latter and often reduces it.

(Excerpts from ART HARDWARE: The Definitive Guide to Artists’ Materials, by Steven Saitzyk © 1987 revised 1998)