bubble type corrosion on outside of clawfoot tub

[csweihe]

Today my clawfoot was released from a 30 year imprisonment behind a cheesy DIY tub surround. Under the curled lip (top edge) there is weird rusty type bubbles. ??? odd. a bit of crumbling around faucet hole but, not rusty in appearance. The tub IS 103 years old (as is the house). I would like to mosaic tile around the outside of the tub for decorative purposes.

I have only laid ceramic tile onto CBB counter tops and floors.

Any idea how to prep the iron surface? Steel wool and oil? wire brush? no oil? Would oil create a barrier and interfere with mastic? should I use mastic?

help, please.

 

[glennjanie]

Hello CSWeihe:
I would use a wire brush head on an electric, portable grinder for the clean-up. Use no oil, it will interfere with the bonding.
Use tile mastic to stick the tile to the tub and make sure it is sealed well with grout and, maybe even a top coat of clear sealer.
Glenn