Hi Lisa! Adding ice cubes or h2o to the oven can really help with crust growth (especially when baking sourdoughs!). Though It's not necessarily Definitely essential, it may also help generate a good looking loaf. Here is a tad more information on the process: Baking bread with steam Delighted Baking! https://theme-decoration25790.thechapblog.com/27822282/an-unbiased-view-of-sourdough-bread