anders zorn canvas chemical synthesis chemistry claude monet cotton drying oil early netherlandish painting fat over lean francisco goya frankincense fresco gesso glaze history of painting impressionism jacques-louis david jan van eyck johannes vermeer john singer sargent la velata leonardo da vinci linen linoleum linseed oil mineral spirits miniver molecule mona lisa oil paint oil sketch palette knife panel painting paper paper marbling paperboard peter paul rubens pierre-auguste renoir poppyseed oil pressed wood raphael rembrandt renaissance roger of helmarshausen slate tempera the blue boy theophilus presbyter titanium dioxide titian turpentine underpainting venice walnut oil water lilies water miscible oil paint wet-on-wet wikibooks wikimedia commons