scumble
Concise Oxford English Dictionary © 2008 Oxford University Press:
scumble /ˈskʌmb(ə)l/ Art
▶verb give a softer or duller effect to (a picture or colour) by applying a very thin coat of opaque paint or a layer of light pencil or charcoal shading. ▶noun a coat of paint or layer of shading applied in this way, or the effect thus produced.
'scumble' also found in these Oxford entries:
