On 21/04/2019 11:15, Another John wrote:
Having a mug of tea with a mate the other day, I bemoaned the fact that
my beautiful mug (on the outside) had acquired brown stains (on the
inside) which can't be removed using the normal nylon scouring sponge.

He said his Mum used to bleach their cups on a regular basis. I'd heard
of this before, but I've never gone near the idea, for fear of poisoning
myself.

What does The Team Think, please?

Cheers
John

Back in the '90s a work colleague at an engineering company used to
drink strong coffee throughout the day and only ever rinsed the mug,
never washing it. After a while someone nearby would get fed up of the
state of it and nip down to the shopfloor and stick it in one of the
pickling baths. It used to come out sparkling.

SteveW