My BIL routinely treated his toilet for mineral stains with diluted CLR
(phosphoric and oxalic acid). Now it's pitted. A wet pumice stone has
long been recommended as a safe way to remove mineral stains from
porcelain, but I've read that it can ruin some toilets.

Are there different qualities of porcelain for toilets, sinks, and tubs?
Are there some that can't be cleaned safely? How can you tell if
you're buying a good one?

I've read that bathtubs can be restored. Are some methods better than
others? Do any work on toilets?

E Z Peaces wrote:
My BIL routinely treated his toilet for mineral stains with diluted
CLR (phosphoric and oxalic acid). Now it's pitted. A wet pumice
stone has long been recommended as a safe way to remove mineral
stains from porcelain, but I've read that it can ruin some toilets.

Are there different qualities of porcelain for toilets, sinks, and
tubs? Are there some that can't be cleaned safely? How can you tell
if you're buying a good one?

I've read that bathtubs can be restored. Are some methods better than
others? Do any work on toilets?

Most tubs are given an epoxy type coating in the home for restoration. Tubs
are coated, toilets are porcelain clay with a glaze. Anything that can clean
the mineral stains can also damage the "glass" coating or glaze. You can
probably buy a new toilet for about the cost of restoration if it could be
done.

Best is to invest in a water softener and eliminate the minerals.