Editing Jacques Maroger (section)

== Critics of Maroger ==
Maroger has been criticized by some modern writers on painting because of his bold assertions about having found the secret formulas of the Masters. The current proprietary Maroger's Medium is in fact the jelly-like medium also known as Megilp (Macgilp, McGuilp, etc.). This material, made by mixing heavy mastic varnish with a linseed oil that has been cooked to blackness with litharge or white lead, was introduced in the late 18th century and employed extensively during the 19th, and therefore is not of centuries-old pedigree.<ref>Mayer, Ralph, and Smith, Edwin (editor). ''The Artist's Handbook of Materials and Techniques (4th edition, revised and expanded)  ''. London, Boston: Faber and Faber. pp. 192, 223, 226. {{ISBN|0-571-11693-0}}.</ref>

The archival quality of the medium itself is controversial in art circles, in part because its documented use dates back less than a century. This is from Michael Skalka, Conservation Administrator, National Gallery of Art, Washington, DC.:

{{blockquote|[Our convervators] know that Maroger and other media do not betray their bad characteristics for a long time. (60 years is not enough time – oil paint isn't even fully dry in 60 -80 years on a typical thickly painted painting) Maroger (1884–1962) did not influence artists until the early 20th century so 19th century works are not affected by his practices. However, recently, two conservators in a museum in New England examined and studied the work of John Stuart Curry who was an avid fan of Maroger. Many of his works have suffered through the use of the medium. Granted, Curry was a zealot who followed Maroger's early and late formulations. Curry's work employed an early Maroger formula that involved leaded oil, resin and in early versions incorporated water based additives. These have suffered the most.}}See the work of Lance Mayer and Gay Myers for more information on Curry and Maroger.

Maroger medium which is not made properly may contain a large amount of dirt and impurities from improperly filtered mastic varnish, or the black oil may be overcooked, both of which would contribute to darkening and weakening of the work.  In addition the overuse of megilp media (or any medium for that matter) tends to create weak paint films. Conservation science has shown that the presence of natural resins like mastic in the paint film causes embrittlement, darkening, and continued solubility. See the work of Leslie Carlyle or Joyce Townsend for problems related to 18th-century painting that contain megilp.