You should look into paper based substrates, they let the heat from UTH's through really well. They don't look as nice but they are much easier to keep clean and handle temperatures better.
The paper based substrate options include:
Paper towels, butchers paper, newspaper, and corrugated wrap.
I personally use corrugated wrap, it looks the best out of the paper based substrates in my opinion
This is where I get mine:
http://www.papermart.com/Product%20P...x?GroupID=4608