8 Things You Absolutely Should Not Put in the Dishwasher — And the Gentle Art of Caring for Your Kitchen Treasures

A dishwasher can feel like one of the greatest inventions in a busy kitchen. You load the plates, add detergent, press a button, and let the machine handle the mess.

But convenience has limits.

Not every kitchen item is designed to withstand the combination of hot water, powerful jets, steam, detergent, and prolonged heat inside a dishwasher. Some objects can become damaged, dull, warped, rusty, or even dangerous. In certain cases, broken glass or metal can also damage the dishwasher itself.

The good news is that avoiding problems doesn’t require complicated rules. Once you know which materials need special care, it becomes much easier to decide what belongs in the dishwasher and what should be washed by hand.

Here are eight common categories of kitchen items that deserve extra attention.

1. Sharp Kitchen Knives

Your expensive chef’s knife may look perfectly suited to a dishwasher, but putting it there repeatedly can shorten its useful life.

The combination of heat, moisture, strong detergent, and contact with other dishes can affect the blade and handle. Even stainless-steel knives can develop spots or corrosion over time, particularly around joints and handles.

There’s another issue: a dishwasher basket isn’t a gentle environment for a sharp blade. The knife can move around during a cycle and come into contact with plates, racks, or other utensils.

Why hand-washing is better

Wash quality knives by hand using warm water, mild dish soap, and a soft sponge. Dry them soon afterward rather than leaving them soaking in the sink.

This takes only a minute or two and helps preserve both the edge and the handle.

2. Wooden Cutting Boards and Utensils

Wood and dishwashers generally don’t make a good combination.

Wood is naturally porous and reacts to repeated exposure to water and heat. A dishwasher cycle can cause wooden boards, spoons, spatulas, and similar utensils to swell, crack, warp, or split.

A cutting board that becomes warped may no longer sit securely on the countertop. Cracks can also make the surface more difficult to clean properly.

How to care for wooden kitchenware

Wash wooden items by hand with warm soapy water. Avoid soaking them for long periods.

After washing, allow them to dry completely.

For wooden cutting boards, occasional conditioning with a food-safe board oil can also help maintain the wood, depending on the manufacturer’s recommendations.

3. Cast-Iron Cookware

A well-seasoned cast-iron skillet can last for generations—but the dishwasher is usually not the place for it.

Dishwasher detergent and prolonged exposure to water can strip away the seasoning that gives cast iron its familiar cooking surface. Once that protective layer is damaged, the bare iron can become vulnerable to rust.

That’s frustrating when you’ve spent time building up a good seasoning layer.

The better method

Most cast-iron cookware should be cleaned by hand according to the manufacturer’s instructions.

After washing, dry it thoroughly. Some cast-iron owners also apply a very thin layer of cooking oil after drying to help maintain the surface.

There are exceptions: certain enameled cast-iron products may be dishwasher-safe. Always check the manufacturer’s instructions for your particular cookware.

4. Nonstick Pans

Nonstick cookware is another category where repeated dishwasher use can be hard on the finish.

The combination of strong detergents, high temperatures, and repeated washing may contribute to the deterioration of some nonstick coatings over time.

Once a pan’s coating becomes scratched, peeling, or damaged, its cooking performance can suffer.

Protect your nonstick cookware

Hand-washing is often the gentler option.

Use a soft sponge rather than abrasive scouring pads, and avoid metal utensils if the manufacturer recommends against them.

Don’t assume that every nonstick pan is identical. Some modern cookware is specifically labeled dishwasher-safe, so the manufacturer’s instructions should take priority.

5. Crystal, Delicate Glassware, and Hand-Painted Glasses

The image above shows one of the more dramatic dishwasher failures: broken glass scattered across the door and floor.

While ordinary dishwasher-safe drinking glasses are designed to tolerate dishwasher conditions, delicate glassware is different.

Fine crystal, thin decorative glasses, antique glassware, and some hand-painted pieces may be more vulnerable to heat, detergent, vibration, and contact with other dishes.

Over repeated cycles, delicate glass can become cloudy, etched, discolored, or weakened.

And if two pieces strike each other during a cycle, breakage is possible.

When in doubt, wash delicate glass by hand

Use lukewarm water, mild detergent, and a soft cloth or sponge.

Hold delicate glasses carefully rather than twisting or squeezing the bowl.

For valuable or sentimental glassware, hand-washing is generally the safer approach unless the manufacturer specifically confirms dishwasher compatibility.

6. Items With Gold, Silver, or Decorative Finishes

Beautiful plates and glasses with metallic trim can be particularly sensitive to dishwasher detergents and heat.

Gold-edged plates, silver decorations, painted designs, and some decorative finishes may gradually fade, lose their shine, or become damaged after repeated dishwasher cycles.

That favorite dinnerware your family has had for years may not be replaceable.

Look for the manufacturer’s instructions

If an item is labeled hand wash only, take that seriously.

For heirloom dishes, antique pieces, or anything with precious decorative details, hand-washing is usually the more cautious choice.

7. Copper and Some Other Reactive Metals

Copper cookware is famous for its beautiful appearance, but that shine can change dramatically when exposed to harsh dishwasher conditions.

Dishwasher detergents and heat can cause copper surfaces to become tarnished, discolored, or dull.

Some cookware may also contain multiple materials—for example, copper combined with stainless steel—so the correct cleaning method can vary from one product to another.