Simply put, it has to do with the starch in flour. As bread bakes, its outer layer (crust) eventually reaches 180°F. At that point, the starches on the surface burst, become gel-like, and then harden in the oven's heat to a crackly consistency. Steam hitting the bread's surface facilitates this process.

Why is my bread not crusty?

Baking your bread at the proper temperatures is important to create the correct cust initially. If the crust will not be thick enough, it will never be crusty after cooling. There is always moisture escaping the bread when cooling. ... The longer you have steam in your oven while baking the thicker your crust will be.

What makes bread soft or crusty?

Breads that have soft crusts are breads that are higher in fat, like challah, brioche and sandwich breads. Almost any amount of fat added to a dough will soften the crust, whether it is from eggs, whole milk, butter or oil. ... I don't know any bakers who will turn down a good tip when it's about getting a great crust.