This journal article, translated from French, discusses ethical and controversial considerations regarding cleaning and varnish removal of oil paintings at the Louvre Museum between 1937 and 1950. Many artists, particularly of the Romantic and Classical periods mixed or overpainted varnishes with paint, or applied tinted lacquers (e.g. Robert Lacquer ) or thin glazes (scumbles) to achieve certain values, tones, shading, modelling, shadows and other effects (e.g. darkening to express linear perspective). Aggressive solvents such as alcohol and acetone may strip or damage varnish-containing layers. Milder solvents (toluene, xylene, benzene) should be considered. Recipes are no substitute for a sensitive and experienced restorer. Reference is made to artists Veronese, Gricault, Delacroix, David, Velazquez, Gros, Rubens, Van Dyck, Watteau, Gozzolli, Courbet, Manet and Bazille, and paintings Marriage of Cana , Light Cavalry Officer , Raft of the Medusa , The Sabines , Liberte Guidant le Peuple , Sardanapalus , Battle of Eylan , Madonna dell' Unilta , Plague of Jaffa , L'atelier , Les Cerfs Dans La Fort , Lola de Valence and The Family Reunion . This is a reference for techniques, preservation, and early conservation treatments of European master paintings. The original French article is attached. -- CCI