Hi Lisa! Incorporating ice cubes or drinking water in your oven can really help with crust improvement (specially when baking sourdoughs!). Whilst It's not at all absolutely necessary, it can assist build a beautiful loaf. Here is a bit more information on the procedure: Baking bread with steam Happy Baking! https://brazilian-wax-laser38159.blogdiloz.com/27723375/a-review-of-sourdough