The trick to restore your beloved baking sheets — without having to spring for replacements — is to wet them and sprinkle on Bar Keeper's Friend's powdered version. If your cookware is made of anodized aluminum, Bar Keeper's Friend could damage its hardened coating. If the water-and-powder paste leaves a smudge behind, you'll want to consider another affordable cleaning hack to revitalize your cooking sheets. Bar Keeper's Friend can also leave scratches on coated, non-stick aluminum cookware. If you're looking to avoid cleaning your baking sheets altogether, consider using protective liners (baking mats, parchment paper and aluminum foil) when you cook and always wash up.