scumble

transitive verb scumbled, scumbling

1. 1. to soften the outlines or color of (a painting) by applying a thin coat of opaque color
   2. to apply (color) in this manner
2. to soften the outlines of (a drawing) by rubbing or blurring
3. to make by either of these processes

noun

1. a coat of color added in scumbling
2. the softening of outline produced by scumbling