I rub off the cosmetic tin flash overlay to expose the lead/tin layer. The flash overlay is an electroplated layer of tin on new bearings that only serves as a dry lubricant during assembly. Some bearing manufacturers calls it a "sliding layer" on their tri-metal bearings. Instead of using Scotch Bright, you can also dip the bearings in lacquer thinner and wipe them with a micro-fiber towel.
Last edited by MouseFink; 12-07-2012 at 01:56 PM.