I cleaned mine several months ago with nothing more then #0000 steel wool and some 303 Aerospace cleaner, but you can use soapy water as a lubricant.
They literally look good as new and I did not use any form of darkening treatments or the like. No back to black or anything like that.
#0000 Steel Wool and a soapy lubricant. Took me about an hour for both, and lots of elbow grease.