Looking at the Vintage cymbal guide, I saw that they posted a flyer from Zildjian where they mentioned how to clean Zildjian cymbals. I was surprised to see that they listed using Comet, Copper Bright, Samae, or any popular brass or copper household cleanser. Here's the link:
http://www.vintagecymbalguide.com/images/literature/zildjian/zildjian_repair_flyer-1.jpg
I know they weren't talking about cleaning vintage cymbals, but I did find it strange/funny that they were so vauge in what to use.