Easy enough to find out if it is shellac or not regardless of age. Put some denatured alcohol on it and if it melts or softens up there you are. Any other finish such as varnish or dried out linseed oil can be removed easily with paint remover. Just don't leave it on too long as some forms of this can cause discoloration to the metal. To me it still seems to have more of a metalic look to it BWDIK ?
Robert