Flemish Maroger is an oil varnish painting medium discovered by Jacques Maroger, painter and former curator of the Louvre in the early 20th Century, who claimed to have found the secret formulas used by Old Masters such as Titian, Rubens, Van Dyck, Velasquez, as well as others. Consisting of Black Oil and Mastic Varnish, this medium comes in the form of a soft jelly, and is used for its great versatility in oil painting.

"The jelly is of an amber color ... It is like a liquid glass with which the painter invests his pigments. It possesses the extraordinary property of congealing in the air and of becoming ductile again at the touch of the brush. Drawn by the brush, it moves fluently over the canvas. As soon as the brush is removed, it becomes firm and congeals immediately - ready, again to become every bit as ductile at the next touch of the brush.*"