Hardware collectors tend to have a favorite method of cleaning and polishing their finds. Mine involves removing paint and dirt by soaking the piece in a mixture of hot water and Arm & Hammer Super Washing Soda, followed by Twinkle Copper Cleaner if the tarnish is particularly heavy, and then polishing with a metal-safe polish such as Nev’r Dull.
Some people spray the hardware with a clear coating, such as shellac (the remnants of which can be removed easily with denatured alcohol prior to re-spraying). I prefer furniture wax, but my hardware is not used, just exhibited, so the wax is unlikely to be worn off through frequent contact.
However cleaned and polished, antique hardware is unlikely to end up looking new, but collectors greatly appreciate a good patina. Whatever you do, don’t polish pieces with rouge and a buffing wheel, because that will round and blur details in the casting.
Allen Joslynis a director of the Antique Doorknob Collectors of America, and the editor of its newsletter, The Doorknob Collector.