wrote in message
...
On Sunday, 5 August 2018 22:52:01 UTC+1, lopt wrote:
"newshound" wrote in message
o.uk...
On 05/08/2018 10:19, lopt wrote:

Have you tried conc nitric acid ? That should get it off, but isn't
that easy to get.

what does that do9 to carbon?

Dissolves it.

No, it doesn't. Even fuming nitric doesn't.

Yes it does with boiling conc nitric.

There are limits to what I'll use as a cleaning chemical. Boiling strong
fuming acids are a good 2 steps beyond that point.

But there isnt anything else except molten potassium nitrate
that will get that carbon off without damaging the enamel.