You can use a cold black oxide refinisher like Creswel’s black oxide concentrate. Caswell’s black oxide refinishing system works perfectly to exactly duplicate the black finish Lionel used on die cast pilots, freight car side frames, and steel wheels and axles. You have to follow some specific steps when working with black oxide. It is an acid, but it’s a low, low, grade acid. So after the dipping process, you must neutralize, and treat the dipped parts. Caswell’s black oxide concentrate is available in small quantities, and is very inexpensive for the DIY crowd wanting to refresh blackened antique model railroad parts……I use Caswell’s system in the shop almost religiously for both automotive, and model railroading use. Somewhere in the archives of this forum, I did a before and after, and pretty’s sure I did some pilots, pilot trucks, etc,…if it can’t be found, and you guys would like a quick overview and tutorial, I’d be happy to do it, ….it literally takes only minutes to get professional results…..
Pat