I always place my cup in the middle of the microwave. I do only cook the plastic in short bursts. No more than a minute each time. Then as I'm getting close to desired temp I only cook in seconds, and check temps. Never had an issue . Except this past time I guess. I also don't have a powerful 1000 watt microwave. Mine is 650 watt I believe. I'm wondering if the mica had more to do with the burning rather than placing cup in the middle.