• Michael Skalka

"... as Clear and Transparent as a Piece of Coal" Part 1


Summary: When it comes to painting mediums used by artists, the debate about their merits or problems becomes a source of heated discussion. The use of a favorite medium like Maroger can take on a spiritual quality and the practitioners employing this medium will express a reverence for the material and techniques related to its use that is almost religious in nature. A well-researched article by Lance Mayer and Gay Myers, “Old Master Recipes in the 1920s, the 1930s, and 1940s: Curry, Marsh, Doerner and Maroger,” reveals the damage done by this type of leaded-oil/varnish medium.


Arguing about the problem associated with Maroger is akin to playing the part of Clarence Darrow against William Jennings Brian in the Scopes Monkey Trial in 1925. To drive home your point, you will have to resort to an argument that is akin to denying the existence of a Heavenly Creator.

If readers of this website recall previous essays on questionable mediums, you will know the argument is never resolved. Leaded, boiled oil advocates will pop up out of their proverbial mole holes to fight again and again. Perhaps the heated oil and lead have finally seeped into their nervous systems and they just cannot process information anymore! (Seriously, handling dry lead pigment and boiling it is not a trivial safety issue. It can cause life-threatening, chronic health problems.)

For those of you who have ever followed the online art forum, Wet Canvas, this is a rehashing of a very old posting I made about Maroger medium. No levity can be expressed with the Wet Canvas group when it comes to discussing mediums. For some, this essay will be the first time they have read the debate on the use of Maroger medium. For others, it bears repeating because Maroger medium and other paint modifiers can cause problems. For me, arguing with Maroger advocates is a lot like seeing the movie, "Groundhog Day." Only the people I had the discussion with on Wet Canvas about Maroger medium in the past don’t look anything like Andie MacDowell.

The most damaging evidence against Maroger medium is revealed in a brilliantly researched article. “Old Master Recipes in the 1920s, the 1930s, and 1940s: Curry, Marsh, Doerner and Maroger,” by Lance Mayer and Gay Myers. (JAIC, 2002, Vol 41, No. 1) It provides a wealth of information on the history and effects of the use of painting mediums, especially, Maroger medium. If after reading it you are not convinced that this medium has hostile intentions for your painting, you have missed the point of this well-documented article and you should ignore the evidence and continue to use Maroger medium, often, and copiously.

The paintings of Reginald Marsh and John Stuart Curry suffered to a notable and extensive degree. Initially, both artists were enthusiastic advocates of Maroger and his mediums. (The use of mediums, plural, is not in error and a point that will be addressed later in part 2.)

No information on the percentage of paint to medium used by the two artists is cited in the article but notes on their studio practices do exist and were quoted. Both Marsh and Curry were liberal with their use of Maroger’s formulations. Mayers and Myers who are conservators, examined paintings in various museum collections and made note of the cracks and wrinkles in the paint surface as evidence of the signs of accelerated drying caused by Maroger medium. Curry and Marsh had paintings that nearly self-destructed shortly after they completed them. Desperate to believe that Maroger held the "The Secret of the Old Masters," they smeared paint with medium all about hoping it would work but shortly thereafter saw the results “unfold” figuratively and literally.

Some contemporary oil painters appear to advocate a “moderate” approach to the use of Maroger Medium. Using 10 percent or less gives them the paint handling characteristics they desire while "feeling" that the volume of medium will do no lasting harm. Advocates argue that moderating the inclusion of Maroger medium will not cause any of the ill effects of the formulation in the medium. This is akin to saying that ingesting only a little bit of radioactive plutonium will not kill you. Trust me, it will.

Research has proven that small amounts of harmful material in an oil film will have a long-term impact on its aging. The addition of natural resin into oil paint will change the nature of the dry film. Drying oils like linseed, actively oxidize to form molecular links to create a paint film. Foreign substances like Maroger alter the film formation, leaving it vulnerable on many levels.

First, it is known that natural resins used in varnishes, aid in making paint more glass-like over time. Oil paint become glass-like on its own without any additional help from natural resins, so the adulteration with resin only serves to worsen the problem.

Second, natural resins create more soluble paint films. This is compounded with both the resins and oil darkening over time so that when a surface applied varnish needs to be removed because it has become discolored and cloudy, the paint containing the infusion of natural resin will react with the solvent mixture used to remove the varnish. The best a conservator can do is to thin the varnish to remove at least some of the discolored varnish coating.

Third, the appearances of paintings with added resin mediums suffer from cracking, flaking and discoloration to a greater degree than paintings with unadulterated oil colors. The other enemies of paintings are shock and vibration from transport, high temperature and humidity conditions around a painting, exposure to light levels and natural or artificial disasters (floods, fires, etc.) In all these cases the incorporation of natural resins in paint, that help to make the paint more brittle serve to accelerate the effects of shock and temperature exposure.

On many occasions, Maroger medium zealots blame conservators for looking only at a painting’s faults rather than their virtues. A conservator, viewed as a “doctor” of paintings, is trained to find the “sickness” in paintings. However, conservators in museum practice see many paintings in good condition. The examination of pictures slated for exhibition and a review of the state of paintings on view in galleries in good condition comprise a greater number than those that need treatment.

It is fortunate that some conservators have the time to write articles about treatments. Conservation literature is filled with articles on how paintings are stabilized and restored. Conservators treat paintings to earn a living. They must work efficiently to support their business. Few conservators have the luxury of being able to study materials and do experiments on the stability or longevity of art materials for the sake of helping artists.


So, if conservators are viewed as “painting doctors,” it stands to reason that many journal articles in their field are devoted to how to treat the “illnesses” in artworks. It is not difficult to find in the literature multiple references to paint that has been compromised by the addition of resin and metallic-oil components. What they have found about incorporating questionable painting mediums is consistent. In general, they diminish a painting's longevity and stability. End of Part 1.


Title quote: "The new medium is as clear and transparent as a piece of coal." A note from John Steuart Curry to Jacques Maroger. June 17, 1942, on viewing the medium Maroger was promoting.

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