The heat-retaining ability of baking stones or unglazed quarry tiles helps significantly to recover lost heat more quickly after the oven door has been opened. A stone also serves to provide more even baking for flaky pie crusts and breads. It pulls moisture from the bottom crust, which helps to prevent a soggy bottom crust for fruit pies and to ensure a crisper bottom crust for bread. The added benefit for bread is the initial heat boost, so vital for maximum oven spring. An oven stone is usually placed on the bottom rack or on the floor of the oven before the oven is preheated and the pan, or bread dough set on parchment, placed directly on the stone itself. It also serves to maintain even oven temperature for other baked items.