The fact that antique finishes (shellac and laquer) are able to be cleared up like new when you introduce the proper solvent is the main reason people cringe when someone puts polyurethane on an antique. Unlike the two oldies but goodies polyurethane can not be “reactivated”. That means the only way to fix damage would be to strip and redo. That means if it had original paint or an original label that would be lost with any refinishing. However if it still has (or someone redid it with period ap

DIY - Shellac - From Flakes to Wood Finish - Easy