Even though pizza stones and irons all look the same – just a slab of hot stuff – a few things can affect how well they work. Here’s what we considered as we searched for the best:
Stone against metal
We specialized in non-glare cordierite ceramic baking stones and baking irons.
Cordierite Ceramic, a material commonly used in bakery ovens, is ideal for baking stones because, as materials science professor William Carty tells us, “It is insensitive to rapid changes in temperature.” So it won’t crack when you drop the cool dough in the hot place.
Ceramic stones are great for baking not only pizza and bread but also biscuits, scones, and tarts. Compared to metal, ceramic transfers heat moderately and will not burn the bottom of delicate baked goods. Susan Reid, senior chef at King Arthur Baking Company at the time of our interview, does a lot of baking on her stone, especially pies. “The ‘oomph’ of the low heat helps keep the bottom crust from sticking,” she said. (Note: Use only ceramic or metal pie plates. A hot stone can cause glass plates to crack from the heat.)
Baking trays, made of solid steel, deliver much more heat than ceramic. They are also much denser than a baking sheet or even a cast iron pan, so they hold a lot more heat. Thin-crust pizzas, such as New York-style and Neapolitan-style pies, bake best with a cast iron because high heat is essential for proper browning and oven spring in a short time. But the heat of the iron is too strong for butter cakes, as evidenced by a batch of dark croissants. The iron was burning the bottoms of the bread we were baking.
Size and shape
Size options are just as important as what the baking stone or metal is made of, because ovens vary. You want as large a baking area as possible, while still allowing for air flow around your stone.
Rectangular stones are more flexible than round ones. A stack of baguettes or a baking sheet will fit into the rectangle. But in a 14-inch-diameter circle? It’s not that simple. Even if you are interested in making pizza, you want as much space as possible to rotate and stack the pie to bake evenly. That said, if you have a small oven and your only option is a round stone, that’s fine. Better than nothing!
When choosing a size, just make sure there is a 1-inch gap between the stone and the oven walls on all sides, because that is important for air flow in the oven. Good airflow not only promotes even baking but also improves your oven’s longevity and performance. If too much heat is trapped in the lower part of the oven, you run the risk of damaging electronic components, such as the ignition unit of the gas oven.
Size
There is a sweet spot when it comes to the durability of stone and metal. If it’s too thin, it won’t hold enough heat, especially for back-to-back pizzas. It is very thick and will take more than two hours to heat first (and hard to move). Depending on the season, that means you could be stretching the dough in an unbearably hot kitchen while the stone is ready. We found the ideal thickness for stone to be 0.5 to 0.75 inch, and 0.375 inch for steel.
A very efficient baking stone or iron is a great piece of cookware. If you are worried about lifting it, stone is a good choice because it weighs much less than steel.
Local texture
In our tests, we found that pizzas baked on stones with rough surfaces were browner, crispier, and puffier than those we made on smooth stones. The pizza we made on the glazed stone turned out amazingly golden, but the crust was loose and had the mouth of a burnt bun. We hypothesized that craggier surfaces provide more avenues for steam to escape, promoting more browning and crispiness.
The surface texture of the cast iron is probably not important as it has higher conductivity than ceramic. But the cast irons we tested, while not as heavy as our favorite cast irons, have the rough texture of the Lodge cast-iron skillet.