Cure for Burnt Bottoms?
I hope I have found the cure for burnt bottoms on my sourdough boules.
I found a table of the heat conductivities of various materials. I had been using metal vessels to bake, and the bottoms of things kept getting burnt in my electric oven.
Not surprisingly, glass is a worse conductor of heat than metal. Air is an even worse conductor. This suggested a remarkably simple solution.
I took two 9" Pyrex pie plates and nested/stacked them. Once stacked, there is an air gap of 1/8" to 1/4" between the two pie plates. This air gap acts as an insulator. To prevent sticking, I sprayed the bottom of the top pan with cooking spray. I then baked some Pillsbury canned biscuits just to test the efficacy of my solution. It worked! No burnt bottoms! Parts of the biscuits were just a little darker on the bottom, but they were nice and golden, not burnt. I think I'm onto something.
A little about my baking setup: I'm using a modified Waring TCO600 6-slice toaster oven and I like it a lot. I modified it by removing the upper heating elements. These caused the tops of things to burn so out they came. Now it just has the lower elements like a full-size oven's bake element. I use a toaster oven because it seems wasteful to use a high-wattage full-size oven for something as small as a boule or six biscuits which use just a fraction of a big oven's interior volume. The toaster oven has a much smaller interior and with my modification draws only 750 watts when the heating elements are on. I had been using a metal "heat shield", the toaster oven's metal baking pan, over the heating elements, much like a gas oven, but found this to be energy inefficient. The insulator only needs to be under the food, not over the heating elements. I had been using a "baking stone" made of Teflon and it worked quite well indeed, but opted for a non-Teflon solution due to (possibly unfounded) health concerns about the toxicity of Teflon. I have ordered a small silicone rubber cake pan to be placed inside the top pie plate as a sort of liner to prevent sticking and eliminate the need to use cooking spray.
Wood would make a great insulator but I don't think it could withstand the oven's 400 - 450 degree heat.
Next I have to adapt this solution to work with a muffin pan.