I've been lurking here for a bit, but this is my first time posting.
I've cleaned up quite a few pieces of rusty, crusty old cast iron, but this one has me tearing my hair out. These pictures were taken after two rounds of baking in the oven's self cleaning cycle, each followed by sitting in a vinegar solution and some vigorous scrubbing. This stuff will not budge, and I'm not even sure what it is!
When dry, the red just looks like a light coat of rust, but it feels smoother than rust does. When wet, it turns that bright red color and no amount of scrubbing seems to remove it. I use a greenie pad, and the water I'm using turns red, but the color on the pan isn't noticeably reduced.
The second issue is a bit harder to see in the pictures. On the inner wall of the pan, there's some black crust. It looks just like the build up you see on a pan before you burn everything off, but this just doesn't seem to be affected.
I'm trying to avoid using the chemical oven cleaner route, but I will if I must. At this point, though, I'm not entirely convinced it would work anyway. This stuff is extremely stubborn.
Any tips? Any ideas on what this stuff even is? Any insight would be much appreciated.