Sargent’s portrait of his teacher (above) is in the collection the Clark Art Institute in Williamstown, Massachusetts. The paintings below are by Carolus-Duran
Here’s a firsthand account of what was taught in Carolus-Duran’s atelier:
“The model was posed on Monday, always in full light, without shadow effect, and against a strongly-coloured backround, which we had to imitate exactly in its relations to the figure. The figure was drawn in in charcoal, then we were allowed to take a sable and strengthen the outline with some dark colour mixed with turpentine, but not to make any preparation, nor put in conventional dark brown shadows.
The palette was set as follows: Black, verte emeraude, raw umber, cobalt, laque ordinaire, brun rouge or light red, yellow ochre, and white (the colors being placed on the palette in this order from left to right).
We were supposed to mix to or three gradations of yellow ochre with white, two of light red with white, two of cobalt with white, and also of black and raw umber to facilitate the choice of tones.
We were not allowed any small brushes, at any rate not for a long time—many months or years.
On Tuesday Duran came to criticize and correct the drawing, or the laying in of painting if it was sufficiently advanced. We blocked in the curtain first, and then put in the figure or face in big touches like a coarse wooden head hewn with a hatchet; in fact, in a big mosaic, not bothering to soften things down, but to get the right amount of light and the proper colour, attending first to the highest light.
The hair was not smoothed into the flesh at first, but just pasted on in the right tone like a coarse wig; then other touches were placed on the junctions of the big mosaic touches, to model them and make the flesh more supple.
Of course these touches were a gradation between the touches they modelled. All was solid, and there were no gradations by brushing the stuff off the lights gently into the darks or vice versa, because Duran wished us to actually make and match each bit of the tone of the surface. He came again on Friday to criticise and on that day we finished off.”
Carolus-Duran’s teaching was considered progressive among academic instructors because of its painterly, direct handling and its emphasis on form and color rather than line. He was an ardent admirer of Velazquez and a friend of Manet.
The essence of Carolus-Duran's method, according to one of his students, is to “seek first of all for absolute truth of tone and colour, and getting this truth in the simplest and most obvious way.”
Sources: John Collier, A Manual of Oil Painting, London 1891, 5th Edition, page 57-59.
Barbara Weinberg: The Lure of Paris: Nineteenth Century American Painters and Their French Teachers. New York, 1991.
More on Carolus-Duran at Art Renewal Center, link.
Lines and Colors on Carolus-Duran, link.
A Manual of Oil Painting by John Collier on Google Books, link.
Ciudad de la Pintura, link.