Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums General Petroliana Discussion Cleaning rust that is 'on top' of porcelain

Muriatic acid will not cause additional porcelain loss on a damaged area. If applied enough times, it will completely remove all rust residue and after drying, that area is prone to flash rusting again in a short time. It will just be a surface rust, but will give problems with an area that will be painted, so additional metal care is warranted if the area is to be left bare for a period of time.
Get a piece of rusty metal out and experiment! Then you'll know what happens in most situations! You don't want to always rely on the experience of others, as there are too many variables!!