I read a good number of threads here on cast iron maintenance, but I still can't seem to find an answer. I recently got a brand new cast iron griddle. It came pre-seasoned, and I just followed the instruction that came with it. In other words, I started off by boiling water in it, drying it, putting some oil in it, and then heating it back up.
Anyway, I've only cooked a few things in it, including chicken breasts (next to no fat), and a couple of steaks (decent amount of fat). The food came out great, but what got me worried was that I noticed that some discolouration/greying started to happen in a circular shape. That shape seemed to be directly in relation to the coil element of the cooktop. Is direct contact to extreme high heat bad for a new cast iron griddle?
Also, the way I've been cleaning it is to boil water in it, wash it out with more water, brush it, and repeat. Then I'd dry it on the stove or in the oven. Since the discolouration started to happen, I tried to put some more oil on it and bake it, but still no luck.
To make matters worse, I just happened to look at the bottom, and noticed rusting! How could this happen? It's only a couple of weeks old, and I've been making an effort to take care of it, never leaving it wet. Fortunately, I was able to get rid of it by scrubbing it with salt and paper towels.
Right now, my canola oil-coated (inside and out) griddle is baking in the oven at 500F.
PS - As much as I love those "grill marks," cleaning between the ridges is a huge pain! Hard to get into, and bits of paper towel tear off and get stuck.