There aren’t too many people who don’t have a dishwasher these days. Not only do they save water and energy, they get your dishes cleaner than hand washing. The final rinse temperature is typically 150º F, guaranteeing a 99.99% reduction in bacteria. However, as great as the dishwasher is, it shouldn’t be your only cleaning method. That’s because some items just can’t take the heat.
Delicate and Fragile Items: Fine china, usually hand-painted, can chip or fade, and crystal glasses can develop clouding or cracking due to detergent and heat.
Wooden Cutting Boards and Utensils: Water, heat and detergent in a long dishwasher cycle can warp wood and strip it of essential oils. Instead, clean cutting boards by hand and allow them to fully dry before storing. For stubborn stains, scrub them with lemon and salt.
Cast Iron Pans: Never put your cast iron pans into the dishwasher, as they can easily lose their seasonings and can develop rust. Instead, hand-wash with a little dish soap and water (yes, it’s okay), then dry thoroughly. Protect the seasoning with a thin layer of oil.
Non-Dishwasher-Safe Plastic Utensils: Do not put plastic utensils that aren't dishwasher-safe into your dishwasher, as thin or soft plastics may warp from high heat. Dishwasher-safe plastic utensils should be placed on the top rack to prevent damage.
Knives: Go ahead and run your butter knives through the dishwasher, but leave all other knives out. The detergents can dull sharp (and often expensive) kitchen knives. Plus, the sharp points can damage your dishwasher baskets if you slide them in facing down. Of course, face-up knives are a safety hazard, so it's better to hand-wash them.
Nonstick Pots and Pans: While nonstick cookware may be labeled as dishwasher-safe, frequent exposure can wear down its coating, so hand-washing is often a better option.
