I'm a little confused. The seasoning of a cast iron pan, if done right, is polymerized. That's when the fat is converted into a polymer, which is more like a plastic, and doesn't wash off without scraping/scratching, burning or a chemical reaction. I have a pretty sensitive nose, but I don't know that I've ever smelled the difference between oil burning and oil polymerizing, but you can burn fat. I'm guessing that that's what you were smelling, with all that fat in the duck. That would definitely affect the flavor of the meat.

Some use an intermediate term for fat that's starting to burn but not to the point of smoking and breaking down--they say "scorch". Others talk about the "smoke point". The smoke point of duck fat is 375° F. Broiling is usually done at that temperature or higher, so maybe it wasn't the best choice to do with duck confit. Good news is your pan should be fine. :)

I'm familiar with the seasoning process, and it absolutely smells different to me. the process of polymerizing smells like plastic. I kind of hate it when it's time to re-season the pan, it makes me want to leave the house.

my husband has cooked with the skillet in the oven dozens of times, but this was the first time it produced that plastic smell. that's why I find it so weird.

my best guess is this: between seasonings, we keep the pan oiled. maybe the raw oil around the edges, handle, etc, polymerized while the duck was cooking. maybe this is the first time my husband actually broiled rather than baked, and the high heat was the difference. I'll ask him.

I should probably add that I'm sensitive to chemical smells. things that bother me are the same things other people don't really care about (like artificial fragrances). so maybe that's the difference, LOL.

Okay, I get it now about what you mean. Leaving your pans oily is totally unnecessary if they're properly seasoned. Spread a thin layer of oil after washing and heat up to make sure it's 100% dry, and add the new layer to the seasoning base. Thin layers work much better, and will be less smell for less time. I still think the likely culprit was the fat from the confit scorching, but I could be wrong. I wasn't there. :) Good luck running down the mystery. There's no reason not to use cast iron in the oven--it's what's on/in it that'll be the issue.

you could be right. the duck meat didn't burn (in fact we agreed it could have been a little crispier). but the fat "puddle" around it -- maybe the very thinnest edge could have scorched. maybe the taste wasn't in the meat, but just because I was smelling it in the air.