Hi Lisa! Introducing ice cubes or drinking water in your oven can really assist with crust advancement (specially when baking sourdoughs!). Though It's not necessarily Certainly required, it might help create a good looking loaf. Here is a little more information on the process: Baking bread with steam Pleased Baking! https://byd-auto69369.bloggactivo.com/27887363/a-review-of-sourdough-pancakes