Case Size: 1/13 oz. WINDMILL Potato Starch is a fine, white starch perfect for thickening sauces, soups, and gluten-free baking. WINDMILL Potato Starch (13 oz) is perfect for creating smooth, lump-free sauces, gravies, and soups. It's also a great gluten-free option for baking, adding structure and moisture to cakes and other treats.