Originally Posted by
McCreed
re: sand-through on edges
This a common area for sand-through to happen. Especially with right angles that only have a very slightly rounded edge.
IMO this is due to a combination of two reasons. One, simple physics. a liquid finish (particularly hand-applied) just doesn't build up on the tight narrow "point" of the edge the way it does on a flat horizontal surface. Two, most people don't think about reason one when they're applying the finish, whether wiping on or spraying.
When I spray a body, I make sure that I concentrate on the edges with a couple passes with the gun (or rattle can) to ensure an adequate layer of material is going on there. Even with wipe-on poly or Tru Oil I take extra care to target the edges.
The other thing I do is during the sanding process. Whether dry or wet, I barely kiss the edge with the paper with very minimal pressure. More like just dragging the paper over it. Just the polishing process alone will be enough get gloss on a small rolled edge and significantly minimise the risk of sand-through.