Here is a quote from Chapter IX of Solomon J. Solomon's book, The practice of Oil Painting, a book on the list of the American Society of Classical Realism
Quote:
Now, we will imagine that you have neglected to scrape off your paint while the study was wet, and desire to continue with it although it has dried. If the work is only partly dry, and too set to be removed with the palette knife, you had best not continue with that study until it is thoroughly set. It is better to start something else meanwhile.
If, however, it is practically dry, how shall we proceed? First of all, take your "plush mat" and erase some of the dark colour from your shadows and background, right up to and even over the outline, not forgetting to place a thick cardboard immediately behind the canvas, between it and your stretcher. This will give you a firm ground to scrape upon, and will prevent abrasions. Repeated covering of already dark paint will lead to muddiness ; but by erasing somewhat, you will be able to preserve the requisite transparent quality. If, at the same time, the light passages are over-encumbered, use your plush mat so that the scraping undulates across the modelling, from side to side of the study, pressing but slightly on the mat. Any uneven pressure may result in ugly ruts, in which eventuality you had best scrape till the immediately surrounding canvas is altogether bare.
|
The pertinent sentence is buried in the middle of all this. I suppose it's not a really big biggie, today, since few people try to preserve depth or luminosity in shadow. Perhaps I'm crying wolf, too. Who knows. It's just that painting is such hard business, and I try to find good sources who have "learned" things to say about it, so I read as many of the old guys as I can uncover.
Harold Speed, another favorite of classical realists, also speaks of making dark areas dull and dead by repeated painting of them.
Just a thought.