According to the very knowledgeable folks on the pizzamaking.com forums, the best surface to bake pizza and/or bread is between 0.5 and 1" of cordierite, which is the kind of ceramic you find in pottery kilns. That's what I use with excellent results.
Well, ORMs are useless if you're of the opinion that string interpolation and concatenation are a good way of composing logical units. Many of us prefer a proper API for doing that, and good ORMs like SQLAlchemy provide us with one.