Don't understand this black shit. I bought my grips powdercoated black. Spent $50 bucks for black powder coated pointed grips. Striped the coating and polished on my buffing wheel, no black shit after a day's ride.
Maybe you guys need to polish and really rub hard for a while to fully remove the oxidation. I use this stuff called Hot Flash, works really well. I do get the black shit while polishing, but after the initial polish and rubbing with a few different rags, no black shit and no black transmittion to the hands.