A dishwasher can save time and effort, but not everything in your kitchen belongs inside it. High temperatures, strong detergents, and powerful water jets can damage certain materials over time. The safest rule is to check the manufacturer’s instructions and follow any “hand wash only” recommendation.

Sharp knives and wooden utensils are two common examples. Repeated dishwasher cycles can dull knife blades, especially when they knock against other items. Wooden spoons, cutting boards, and handles can absorb water and heat, which may cause them to crack, warp, or lose their finish. Hand washing with warm, soapy water and immediate drying can help them last longer.

Delicate crystal, fine china, and cast-iron cookware also require extra care. Crystal and decorated porcelain can become cloudy, chipped, or damaged, while decorative finishes may gradually fade. Cast iron can lose its protective seasoning in the dishwasher, increasing the risk of rust. Gentle hand washing and thorough drying are generally better choices.

Nonstick cookware is another item worth treating carefully. Although some manufacturers make dishwasher-safe nonstick pans, repeated exposure to heat and detergent can shorten the life of the coating. Unless the manufacturer specifically says otherwise, hand washing with a soft sponge and mild dish soap is a simple way to help preserve the surface. Allow the pan to cool before washing to reduce the risk of warping.

Finally, be cautious with containers that have adhesive labels and insulated travel mugs or thermoses. Heat and water can loosen labels, leaving sticky residue behind, while excessive heat may damage the vacuum seal of some insulated containers. When in doubt, check the care instructions before loading an item. A few extra minutes of hand washing can help protect your favorite kitchen tools—and your dishwasher.