Porcelain/Enamel surface eaten up in bathtub...
I have a good old cast iron tub. Recently I notice there is a trail of the porcelain/enamel surface eaten up -- perhaps by chemical?
It's right below the tub shower door.
I think that trail line goes 1/16" under the rest of the tub surface.
The surface at the bottom of the tub is pretty rough already--probably from harsh cleaners roughing up the surface over the years.
This trail however is quite obvious. I wonder how to repair this surface section (repair that lasts) so it's flush again w/ rest of the surface or not noticeable again.
Or it is too eaten up to be fixed? Time to get a new bathtub?
PS: Actually, is this an enamel or porcelain surface?