Engineered baking stones can be made from a variety of materials, including certain types of concrete, with heat transfer properties similar to clay stones. Commercially, they are used to line pizza and other baking ovens.
In baking, stones are best used in making crispy breads. Stones impart high, even heat, that quickly cooks the outside of the dough, and seals the moisture inside, for more tender and more even baking.
On Using Pizza Stones
Do not use stones to bake items that have a significant fat content, like cookies and turnovers. The stone would absorb the fat which, during subsequent use, will burn off, causing smoke and an unpleasant and possibly noxious odor.
Rough edges on stones can be smoothed with sanding paper, an old grinding stone or piece of brick.
Before first use, wash the stone with water and a brush; do not use detergent, which would permeate the surface and alter the taste of subsequently cooked foods.
Breakage of stones will not generally occur under normal use unless dropped or subjected to thermal shock.
Thermal shock occurs when objects of substantially different temperatures come in contact with each other. Thermal shock causes breakage that is not covered under any warranty, so never do things like put a frozen pizza on a hot stone, or plunge a hot stone in water - you get the picture, I'm sure.
Staining is normal with regular use. You can minimize it by spreading coarse corn meal over the surface before placing dough on the stone for absorption. You can even sand down the surface, by hand, or with a belt sander on larger stones.
To keep pizza or bread dough from sticking to the stone, sprinkle lots of coarse corn meal on the preheated stone.
Using mitts, you can transfer the entire stone to heatproof trivets (to protect the surface) right on your dinner table. The pizza or bread will stay hot, and you can cut right on the surface.
There are differences between different brands of pizza stones. The thicker it is, the more heat mass it produces, which results in more uniform and somewhat quicker baking. The thinner stones are lighter, and, to some extent, make up for their thinness with concentric or other strategically placed feet, to redirect and store heat.
The best way to get a pizza onto a stone in the oven, to check its underside while baking, and to get the pizza out of the oven after it's cooked, use a Pizza Peel (Pizza Paddle) that is the same size, or slightly larger, than the pizza or bread you'll be transferring to the oven. To care for a wooden peel, just keep it dry, floured while in use, and brush cleaned. Avoid leaving wooden peels on hot surfaces. It it warps, leave overnight with the warp facing up and it should flatten out. If you want to seal the wood, use only food grade mineral oil.