8 Things You Should Never Put in Your Dishwasher

Many of us, myself included, would have a hard time thriving without a dishwasher. Sure, we’d survive, but buried under an overflowing, never-ending pile of cooking tools, dishes, and food containers to wash. (It seems pretty never-ending even with a dishwasher.)

Though a dishwasher is perfect for most everyday plates, bowls, cups, and utensils, its high water temperature can wreak havoc on certain kitchen items. Also, high-alkaline dishwasher detergents can “dissolve many things, including human tissue.” (Yikes.) To extend the lifespan of your kitchen essentials, always hand wash these items.

Don’t put wood in the dishwasher

Cutting boards, wooden spoons, and wood-handled knives have no place in the dishwasher. The hot water can warp it, detergent can scratch it, and the drying cycle may crack it. Instead, simply wipe it down, hand wash in warm soapy water and dry immediately, or use this baking soda and lemon juice method.

Don’t put china, hand-painted glass, or crystal in the dishwasher

If I could give one piece of advice to the naive domestic singleton who put together my wedding registry more than a decade ago, it would be this: Don’t get anything you can’t put in the dishwasher. While gorgeous and elegant on the rare annual occasion I use the china, crystal, and silver-plated utensils I was gifted, entering the kitchen afterwards is an emotional lampoon of deflation and regret. Hand-painted designs, gold filigree, and an easily-chipped surface are no match for the harsh conditions inside your dishwasher.

Likewise, the lead oxide in crystal wine glasses and champagne flutes will be damaged by the alkali in dishwasher detergent, leaving their once-gleaming surface with a dull and cloudy residue.

Don’t put cast-iron and copper cookware in the dishwasher

When a cooking tool gives you well-seasoned, naturally nonstick, evenly-distributed heat, you need to treat it right. And that means not putting anything cast iron into the potentially corrosive, rust-inducing climes of your dishwasher. Instead, wipe it down with a soft cloth or wash it in mild soapy water, towel dry, and immediately re-season it. Using soap is OK, but keep it brief — don’t let it soak in suds.

Copper offers superior heat conduction — and a penchant for tarnishing. As such, don’t put this high-end material in the dishwasher or it will become dull and discolored.

Try to avoid putting nonstick pots and pans in the dishwasher, too

The coating on nonstick pots and pans easily flakes away under the high heat, water pressure, and general chaotic jostling of the dishwasher. Harsh detergent can further damage the surface, shortening your nonstick cookware’s lifespan. When you can, stick to a paper towel wipe down, a brief “steam clean” or a gentle lukewarm soap bath.

Don’t put your “good” kitchen knives in the dishwasher

While your basic, nightly dinner knives will hold up fine in the dishwasher, your bespoke steak knives and sharp food-prep knives are verboten. The abrasiveness of detergent will dull the knives’ blades, increasing the chances you’ll put yourself on the hamster wheel of endless sharpening. Additionally, hot water loosens the handles and causes rust over time.

Don’t put cheese graters in the dishwasher

If you already knew cheese graters (and garlic presses!) were best kept out of a dishwasher, why have you been keeping this knowledge a secret? First, just like those of sharp knives, the dozens of tiny blades can dull over time in the dishwasher. Secondly, the small holes trap food particles that even your dishwasher’s water blasts may not be strong enough to dislodge. For both reasons, soak and wash by hand with a scrub brush.

Don’t put thin plastic containers in the dishwasher

The plastic of some containers (for example: takeout, sour cream, margarine tubs) is simply too thin and soft to withstand the dishwasher’s heat — many will melt, warp and otherwise become un-closeable after one cycle.

Other plastic items are a toss-up. While many plastic bowls and plates are dishwasher-safe (and will say so on the underside), they are almost certain to become rough and scratchy over many dozens of washes. It’s always best to place them on the top rack, away from your washer’s heat source.

Don’t put sticky labels in the dishwasher

If you’ve ever looked a dirty glass jar with an already peeling adhesive label and thought, “Oh, perfect, I’ll just let it go through the washer, the heat will get it right off,” two things: 1) You’re not alone, I’ve totally done this, and 2) We are wrong. The pieces that come off in the washer can clog the filter or drain, causing a potential need for repair down the road. And nobody wants a broken dishwasher.