I'm in the process of finishing a box with shellac and have a question about achieving a smooth surface on the top. The French polish method of padding the shellac on in multiple thin coats is working well for the exterior sides of the box and I'm really happy with how they're turning out. However, the top panel is recessed by about a quarter of an inch from the top of the sides so I can't slide the pad off of the edge like I'm doing on the sides. This is making it tough to get into the corners while keeping everything smooth. Is there some trick to getting an ultra smooth application on a piece that has raised edges? Can I thin the heck out of the shellac so it self levels or will I have to sand the finish level then work up through pumice and rottenstone?