I found out something interesting recently when I called a company that specializes in redoing cast iron fixtures. I was told that when a claw foot tub went home with a new buyer, the outsides were never painted...they were bare cast iron. He said the homeowners didn't like that bare metal so they painted them. I NEVER knew that. His recommendation to me was once I had the outside blasted, not to paint it. I told him, "but it will rust". He said it will still rust with paint on it, it will just take longer to come through the paint. He said that it was cast iron and there would always be rust in it...you can't get away from it. He said I could put one light coat of a clear sealer on it. I said won't it still rust since it's being sealed like you mentioned with the paint. He said it wasn't the same...had something to do with the fact that paint has pigment in it and the sealer won't. Has anyone ever heard this? Has anyone ever redone a clawfoot tub (outside surface) and not repainted it?!!! If so, I'd be curious to know how it has held up?