So what can this bread teach us about ovens and heat? How does bread baked in a regular oven get such a nice, open crumb? First of all there’s the wetness of the dough, which means more steam and more expansion. However you need heat penetration to create that steam, and more than that rapid heat penetration so the steam can expand the loaf before the crust hardens. How to achieve such rapid heat penetration in a home oven? Why, the tricks I showed you, of course, combined with a small loaf size. That’s a surprisingly important factor when trying to achieve artisan-style, open-holed crumb at home: keep your loaves small. That’s part of the trick of the Pugliese bread I did before the holidays. Those loaves are no more than a pound. 14 ounces, in fact. And that lets the heat soak in before the crust firms up to the point that it holds any additional rise in like a girdle.