High-pressure water jets can crack or shatter delicate glass against other porcelain. Harsh cleaning agents and high temperatures can permanently etch the crystal surface, leaving it dull no matter how hard you polish it. Additionally, delicate gold or silver details can fade, flake, or completely wear away.
Here’s how to care for them: Line the plastic bowl with a towel to prevent slipping, and gently wash the parts with a mild detergent and lukewarm water. Rinse thoroughly and allow to air dry on a rack or gently dry with a lint-free cloth. Never place heavy objects on delicate parts.
3. Cast iron cookware
Cast iron pans are undisputed kitchen tools, but they don’t stand up to the dishwasher.
Harsh detergents and high temperatures completely remove the polymerized oil layer—known as seasoning—that gives cast iron its natural non-stick properties. Without this protective layer, iron quickly rusts when exposed to moisture and air. Over time, repeated dishwasher washing significantly weakens the iron’s surface.
Here’s how to care for them: Hand wash with warm water and a stiff brush (soap is rarely needed). Dry the pan thoroughly on the stove over low heat, and lightly oil it after each wash to maintain the nonstick coating. Never soak cast iron for extended periods.
4. Cookware with non-stick coating
This may seem counterintuitive, as non-stick pans are designed to be easy to clean, but they are not dishwasher safe.
Harsh detergents and high temperatures damage nonstick coatings (such as PTFE or Teflon), causing them to peel and lose their effectiveness. This accelerates wear, meaning you’ll need to replace your expensive pans much sooner.
How to care for them: Hand wash with a soft sponge and mild detergent. Avoid abrasive cleaners, such as steel wool. Always allow the pan to cool completely before washing to prevent cracking. Although some newer ceramic pans are advertised as dishwasher safe, hand washing will always extend their lifespan.
5. Anything with self-adhesive labels
We’ve all tried to remove a burnt-on sticker from a plate after washing it in the dishwasher – it’s a nightmare.
Under the influence of heat and water, labels disintegrate, leaving a stubborn, sticky residue on your plate and in your dishwasher. Worse still, paper fragments and melted glue can clog dishwasher filters, drastically reducing cleaning efficiency. You’ll spend more time scraping off residue than you save by using the dishwasher.
How to care for them: Always remove all labels and stickers before applying them. To loosen the adhesive on stubborn labels, soak them in warm, soapy water, then carefully remove any remaining adhesive with a razor blade or scraper.
6. Thermal mugs and thermoses
Thermal mugs are great for keeping drinks at the perfect temperature, but washing them in the dishwasher can damage their mechanisms.
Intense heat can damage the vacuum seal between the double walls, reducing the cup’s ability to retain temperature. Additionally, plastic lids and rubber seals can warp or crack, leading to leaks, and harsh cleaners can leave a residual chemical taste or odor inside the container.
