Well, I have some of those things I was told to mix into a paste...

The two worst pans actually yielded to Cillit Bang overnight and a light scrape with a very blunt knife, then scotchbrite pads. Those were deposits.

THere are a couple of others that are discoloured but seem to ahve no deposits. I'll try teh pastes in them.

I also have an old Sunbeam powered frying pan - glorious historic artefact - but while the inside was fair the outside was patchy black. It is currently soaking in a bucket of a household cleaner with ammonia (but you can't immerse the electrical controls or connections).

Also running dishwasher loads of old partial dinner and tea services. All bar one is incomplete - but they were good china in their day...

I know I can't regularly run them in dishwasher or they will bleach, but one run should be OK.