Hi Lisa! Introducing ice cubes or drinking water towards your oven can really help with crust growth (particularly when baking sourdoughs!). While It's not at all Totally necessary, it can assist create a wonderful loaf. Here is a little more information on the process: Baking bread with steam Happy Baking! https://mapengineoptimize71481.madmouseblog.com/8676323/the-definitive-guide-to-sourdough