FP shellac can be used to re-seal nearly any type of damage, if the aim is to seal the wood to prevent it from getting stained from dirt. Whether it will show or not depends on the degree of damage and the original finish. If there's no damage to the wood, a shellac original finish usually repairs quite well, provided the tint is matched, which is one of shellac's strong points, since the new finish blends—bonds chemically— into the original finish, though older an original finish (on the order of many decades old) might not take the new finish quite as well. If there's a ding in the wood, a repair will likely show, though it could be made to stand out less with filling, depending on the damage and the wood, since repairs can be more easily made invisible or nearly so on dark woods. If the original finish is lacquer or a synthetic, it's a toss-up, depending on the damage and its location, but FP shellac will not blend into those finishes like it does on an original shellac finish. There's kind of an art to it. I think Frank Ford's site, frets.com, has some information.