From what I understand from chrome shop guys is that the chrome plating over the nickel and copper is so thin, you should never use an abrasive polish or cleaner. At least not to bring back the shine. Not unlike paint, every time you abrade the chrome (or paint) you remove some of the material. With any metal coating, that usually allows the elements to attack it more as there is less of it to resist oxidation. If you must polish, I am a fan of using a cleaner type wax or 3m Finesse It. The abrasives in these products is super fine. It is kind of telling I think, that chrome shops don't polish the chrome before it leaves their shop...it is as shiny as it's going to get right out of the tank. They rely on the highly polished finish of the acid copper and copper to make the reflection, not polishing the chrome. Also, chrome is so hard it is practically impossible to polish it (with material available to the average person) but not to remove it by using abrasive products.