In article ,
"Nodge" writes:
I fitted a new enamel bath a couple of months ago and I've noticed the first
traces of scale forming around the plughole. I checked on the instructions
for both Viakal and Cillit Bang, both of which say not to be used on enamel.
Can anyone recommend something safe? I thought vinegar possibly? - or would
this attack the metal plughole?

It might attack the enamel same as the commercial descalers.
Enamel may be hard, but its surface is easily attacked by acids,
which takes off the shine which in turn makes it harder to
clean. Use a bathroom cleaner designed for the job which
claims to be safe on enamel.

--
Andrew Gabriel