Grease solvent?

the balls that are not solid but are coated are generally considered 'ker-app' by the well-read skateboarder. the reason is that the metal can expand or contract under heat and the ceramic coating can crack off with disasterous  results.

so if you go ceramic, go quality ceramic, with solid ceramic balls.

J

Now the guy that wrote that tackletour article is serious about his bearing cleanliness!