I inherited a pretty great cast iron skillet from my mother when I moved into my first apartment this year. I've been cooking with it for several years, and know the general rules when it comes to cast iron. The seasoning on this particular skillet was functional but not great, so I decided to give it a boost by reseasoning it. I cleaned the pan thoroughly with soap (which I would ordinarily never do), coated it with a layer of olive oil, and then baked it upside-down on a baking sheet at 400 degrees for one hour. I let it cool down in the oven. When I took it out and turned it over, I discovered that the part of the bottom surface of the skillet was very sticky and bubbly. Not wanting an uneven cooking surface, I tried to smooth the bubbles. Instead they popped and shed horrible dark brown flakes everywhere, and underneath, I could see that there was a perfect layer of seasoning. However, when the pan cooled off completely, the sticky layer became hard and almost glass-like.
I figured I messed up, so I would just strip the pan and start over, but this glassy surface is impossible to remove. I've tried everything - scrubbing with salt and potato, soap, vinegar... nothing will get this weird seasoning layer off, and the rest of the pan is going to become irreparably damaged if I keep this up. Has anyone heard of anything like this before? What is it, and what's the best way to strip and reseason this pan?