Stale bread isn’t necessarily spoiled bread. If a loaf has simply become hard, dry, or chewy but has no mold, strange odor, or slimy texture, it can generally still be eaten. Staleness happens mainly because of a process called starch retrogradation, in which starch molecules reorganize as the bread sits, changing its texture and causing the crumb to become firm.

The important distinction is between stale and moldy. If you see fuzzy green, white, black, or otherwise unusual mold, throw away the entire loaf rather than cutting off the affected section. Because bread is porous, mold can spread beneath the surface even when you can’t see it. Sourdough may stay pleasant longer because its acidity can slow some of the changes associated with staling, but it isn’t immune to mold.

Luckily, hard bread can often be brought back to life with a little water and heat. For a whole loaf, lightly wet the crust, wrap it in foil, and warm it in a 300°F (150°C) oven for roughly 15 minutes, then unwrap it and heat it for a few more minutes to crisp the crust. For individual slices, a light sprinkle of water followed by toasting can restore some softness while keeping the edges crisp.

And if your loaf is simply too far gone for sandwiches, don’t throw it away just yet. Stale bread is actually perfect for croutons, breadcrumbs, French toast, and bread pudding. So the next time you find a rock-hard loaf in the kitchen, check it carefully for mold first—if it’s clean, you may have the perfect ingredient for your next recipe.