Sanding off gunk from Cast Iron Pots -- under built up oil, skillet is orange
I've inherited some cast iron pieces, and I've read quite a few threads on CH about how to deal with them. Armed with that info, I've set to work scrubbing off the gummed up stuff that was layers thick on these skillets, and under all that I'm finding an orange layer. I'm assuming this is rust? I didn't realize it could grow under the oil. Do I need to scrub until all the orange is gone? Or am I just scrubbing till the surface feels flat, and then oiling and heating them to re-season? Thanks!
Is there a way for you to post a pix? If is is and enamel coated cast iron pot, like Le Creuset or Staub, oven cleaner can work wonders. If it is poorly treated plain cast iron you can run it through the self cleaning cycle of your oven. You will end up with some orange residue, wipe it out and reseason. It will be great.
I second the self cleaning cycle in the oven for plain cast iron, I've done it before. It leaves you with perfectly bare cast iron. There will be zero seasoning left, it's exactly like seasoning a brand new pan.
But I did this to pans that were orange with rust inside and out. If you have some rusty spots, sometimes a good scrub with an SOS pad and light reseasoning can fix it quite well.
I third this! :)
For pans that are really rusty:
Tossed onion chopped into quarters in a blender with enough white vinegar to blend it in to a smooth pasty puree.
Slather puree all over the rusted areas - be generous.
Absolutely carbonize the onion into black crust on your gas grill or (if you have GREAT ventilation) in your oven. The black carbonized puree will flake off to reveal a rust-free surface that is ready to season.
(In theory [though I have never done this] I suppose you could simply run the pan at that point through the self-cleaning cycle.)
Here is the "sciencey" part explained:
You've gotten good advice already. If you want to be sure you're starting with non-oxidized cast iron, after the oven cycle, take the pans to someone who has a bead blast cabinet (a lot of car mechanics do), and then immediately wipe with oil until you can start your seasoning. Not necessary, of course, just certainty you've got no oxides under your seasoning.