This is a term which does not exist in any artist journal or book; however, artists use the technique to drop a heavy wash on to a receding one. Background layer wash as it should be called, has part of its hard edge removed by wetting the edge with clear water then lifting out the colour with either a dry brush or a dry soft tissue. The process is repeated until all trace of the layer, up to that point is removed, or nearly so. When the surface is completely dry, the next darker wash is applied sweeping over the area which was removed. By this application, the previous layer should not show or penetrate through subsequent layers.