Bread baked on a baking stone. John Loo / flickr / 2009 / CC BY 2.0
Baking stones are used as a baking aid in modern gas and electric ovens. They are porous, and so absorb condensation from what is baking on top of them, causing a crisper crust. They can make oven-baked fries crisper, and puff pastry crispier and puffier.
They come as flat, square, unglazed quarry tiles about 25 to 30 cm (10 to 12 inches) large. The thicker they are, the better, because thicker ones will hold more heat. Some are around 1 cm (½ inch) thick, but ideally, they will be 2 cm (¾ inch) thick.
They must be unglazed, not only because the glazing contains lead that isn’t food safe, but also because you need them to be porous in order to absorb condensation.
They can be awkward to work with, as several are required and you have to move them around. Some stones will have metal lifts on them to help you put them into and take them out of the oven.
Some feel that because baking stones retain heat, they can help your oven to run more efficiently and lower your energy costs. They forget, though, that they can be expensive to heat up in the first place. Many people recommend to run your oven at 260 C (500 F ) for one hour first to heat up the stones before even cooking on them. Though, as some compensation, pizza put on heated baking stones will only take about 10 minutes to cook.
Large baking stones are made for cooking pizza on. See separate entry on Pizza Stones.
Cooking Tips
Clean new baking stones first with a baking soda solution, rinsing well (don’t use soap, it can be absorbed in.)
When putting them on an oven shelf, leave a 10 cm (two inch) space all round on the shelf, to allow air to rise and circulate. They will likely smoke the first time you use them.
Don’t leave wide gaps between the tiles. Dough tends to harden the instant it hits heated tiles — including in any gaps.
Put baking stones in the oven when you start heating the oven. A sprinkle of water on the stone should evaporate immediately if the stone is hot enough to cook on.
You put what you are baking right on top of them.
A stone can stay hot long after the oven is off; always use oven mitts. Don’t remove a baking stone from the oven until it is totally cool; some say that even the shock of sudden cooler air can crack it. Though, some may have flaws in them that will cause them to crack when cooling, no matter how careful you are.
To clean, allow the stones to cool completely, then remove, scrape off any food or drippings, then rinse with warm water. You can scrub with baking soda if you wish, but never soap: soap will go into the stone.
Eventually, over time, oils will go into the stones and make them non-stick, shiny and dark.
Some baking stone fans say you don’t have to remove them from the oven, ever.
Baking stone heating in oven. Thomas van de Weerd / wikimedia / 2010 / CC BY 2.0