I actually have 2 questions. First of all, how do I remove hardened resin that has attached to the back of the bezel? Secondly, if it turns out that I haven’t put enough resin in the bezel, can I add more after it hardens, or do I have to start all over.
For a sandpaper choice, try to start with the finest grit possible. If it’s a big/thick drip, you may need a 400 grit, otherwise, a 600 grit may be able to do it.
If you work with the resin within 48 hours of its curing, you may be able to (1) ply it off. (If you wait longer it will be too hard); too early and the resin is too stretchy and won’t come off in one piece).
(2) rub it off with nail polish remover, but this will leave a dull finish so I usually put a layer of resin on the back, intentionally this time. (3)Carefully use a heat gun on the back only enough so it is easier to pry off. Too much heat will ruin the whole thing!