the black iron pan, use a green (or black, which is rougher) nylon scourer and a bit of WUL. Rub the inside with oil when clean enough. It will rust if left with water and powder in it. You can also get rust off with the scouring pad.
enamelled pans, you can put in the dishwasher or use a scouring pad with WUL.
Both my le Creuset frying pan and my stainless steel frying pan had a layer of carbon on the bottom where ex didn't wash up the outside (he often fried himself a full English) and I dealt with them as follows:
Le Creuset - soaked in hot detergent for some time, chipped off with knife over several sessions, scrub with one of those stainless steel squiggly things.
Stainless steel - same, but layer was quite thick. So heated pan, quenched in cold water, as figured pan would contract more than carbon - which it did, it kind of crazed. Then attacked it over several sessions with the knife, plus a hammer, at a v shallow angle. (This coated the kitchen worktop and floor with a layer of black specks )
The le Creuset I tackled while Ex was still in residence, the other pan I did after he had finally moved out, when I finally had the time, space, and inclination Plus looking at it kept bringing back my annoyance at him And the chiselling was very satisfying!
I have the black cast iron frying pan and shallow casserole dish. I put them (dirty) in the oven when someone dropped in the other day and then preheated the oven with them still in there. There are badly marked with burned in residue.. What's best to do please?