That's a hard question. It's glacis in French, with no word per se for scumble except frottis, which is more of a rub. I think the term is vague because so many artists don't know how to glaze.... it's more in the thinness of application than in the transparency of the paint, made that way with extra medium. I'll think about it. Bouguereau did this rubbing, frottis, all over. After a few layers, the paint looks quite solid. It's the only way I know to get those gentle gradations.
