Polymer clay (Fimo) isn't clay. It's a polymer that turns to plastic when cured in the oven. It cooks at 275 for 30 minutes. I usually cook it for 45 to 60 minutes because some of the pieces I do are a little thicker. Never had any problems.

Yesterday I opened the over, smoke poured out, and I ended up with this:



An hour at 375. Oops. I wanted to be really pissed, but just couldn't get there. Luckily I was able to salvage all the metal parts.

Hopefully the batch I have in now will do better.