07. After about 10 minutes in the sun, the filler was dry enough for Robert to sand using 80-grit sandpaper, first with the buffing wheel, then by hand. Next, he used 150-grit sandpaper to shape the body filler with the curves of the fender. Robert emphasized the importance of feathering/tapering the edges of the body filler. You don’t want to leave a noticeable edge when priming or painting, otherwise it will clearly show.