Over-cleaning cannot be undone. Remove dirt, grease, and moisture from the surface. Vacuum the item to remove dirt. If the condition of the finish is so bad it cannot be saved, fine bronze wool or very fine emery cloth can be used. To remove rust use an abrasive softer than the iron itself.
Light rust is removed by rubbing the item with very fine bronze wool and mineral spirits.
Strong abrasives are not recommended for historical iron objects. After the outer layer of rust has been removed, the object should be protected as formation of new rust will result. Some experts recommend avoiding the use of commercial rust removers on valuable items as they can cause pitting or etching of the metal surface. If used, follow directions and remove all residue of the rust remover. Power grinders and wire wheels leave scratches on the surface.