The dishwasher feels like the easiest solution in the kitchen.

Dirty dishes go in.

You press a button.

A little while later, everything comes out clean.

But there’s one mistake that can quietly cost you money:

Assuming that anything from the kitchen belongs in the dishwasher.

Some items can warp.

Some can rust.

Some can lose their finish.

And a few can become damaged so gradually that you don’t realize the dishwasher is responsible until it’s too late.

The good news is that you don’t need to memorize dozens of complicated rules.

There are a handful of kitchen items that are much better treated gently.

1. Wooden cutting boards

Wood and dishwashers are a bad combination in many cases.

The combination of hot water, moisture and drying heat can cause wood to swell, warp, crack or lose its finish.

That doesn’t mean every wooden product is identical. Some manufacturers may specifically approve certain treated wooden items for dishwasher use.

But unless the manufacturer says otherwise, hand washing is the safer choice.

Whirlpool specifically advises against putting wooden cutting boards, wooden salad bowls and knives with wooden handles in the dishwasher.

After washing a wooden cutting board, dry it thoroughly rather than leaving it sitting wet in the sink.

2. Wooden spoons and utensils

That wooden spoon you’ve had for years may look tough.

But repeated dishwasher cycles can gradually change its shape and surface.

Wood can absorb water, expand and contract as it heats and dries, and eventually develop cracks.

Once a wooden utensil starts cracking, food and moisture can get into those damaged areas.

For something that takes only a few seconds to wash by hand, it’s usually not worth the risk.

3. Your good kitchen knives

This is one of the easiest mistakes to make.

A knife may technically survive a dishwasher cycle, but that doesn’t mean the dishwasher is the best place for it.

High-pressure water, detergent, heat and contact with other objects can dull or damage the blade.

Sharp knives can also damage the dishwasher’s racks if they are loaded carelessly.

Whirlpool recommends hand washing kitchen knives, while its guidance also warns that sharp knives can become dull or nicked in the dishwasher.

And if you own an expensive chef’s knife, there’s even less reason to risk it.

A quick hand wash, rinse and dry is usually the better routine.

4. Cast-iron cookware

Cast iron is another classic example.

The seasoning that gives cast iron much of its cooking performance can be damaged or stripped away by dishwasher detergents and washing conditions.

Once the protective seasoning is compromised, the iron can rust.

Whirlpool’s guidance specifically states that dishwasher washing can remove the seasoning from cast iron and lead to rusting.

So that heavy cast-iron skillet may be one of the dirtiest-looking things in your kitchen after cooking, but it’s still better cleaned according to the cookware manufacturer’s instructions rather than automatically thrown into the dishwasher.

5. Nonstick cookware

Nonstick pans deserve some extra caution.

Dishwasher detergents, heat and repeated washing can gradually affect certain nonstick coatings.

The important word here is certain.

Not every nonstick pan has identical construction, and some manufacturers specifically label their cookware dishwasher-safe.

That’s why the manufacturer’s instructions should win.

Whirlpool recommends checking the manufacturer’s guidance and generally lists nonstick cookware among items for which hand washing is recommended.

If a nonstick pan is expensive, hand washing is a small price to pay for extending its useful life.

6. Copper cookware

Copper looks beautiful when it’s polished.

Unfortunately, dishwasher detergent and high temperatures can change that appearance.

Copper and some other reactive metals can become discolored or develop surface damage during dishwasher cycles.

Whirlpool lists copper among cookware materials that generally should not be put in the dishwasher.

If you have copper cookware that you actually want to keep looking beautiful, follow the manufacturer’s care instructions rather than treating it like an ordinary dinner plate.

7. Fine china

Your everyday ceramic plates may be perfectly fine in the dishwasher.

But that’s very different from antique, hand-painted or decorated china.

High water pressure, detergent and heat can gradually affect delicate finishes and decorative details.

Whirlpool advises checking manufacturer recommendations and specifically warns that antique, hand-painted and certain decorated china may fade or be damaged.

If a plate is valuable because it has been in your family for generations, hand washing is usually the safer choice.

8. Crystal and delicate glassware

Not all glass belongs in the same category.

Ordinary dishwasher-safe glassware can generally handle a dishwasher.

Delicate crystal is different.

Repeated exposure to dishwasher conditions can cause damage or clouding in some types of delicate glassware.

Whirlpool notes that some crystal can become etched with repeated dishwasher washing and recommends checking the manufacturer’s instructions.

If it’s your everyday drinking glass, check the label.

If it’s a delicate heirloom wine glass, I’d give it the gentler treatment.

9. Insulated travel mugs

That insulated coffee mug may look like the perfect dishwasher candidate.

But the heat and water can potentially affect seals and insulation.

Some travel mugs are dishwasher-safe, while others specifically require hand washing.

So don’t guess.

Check the manufacturer’s instructions, especially if the mug is designed to keep drinks hot or cold for hours.

Whirlpool specifically lists insulated mugs and containers among items that may be damaged by dishwasher washing.

10. Thin or disposable plastic

This one is especially important.

Some hard plastic containers are perfectly fine in the dishwasher, particularly when they’re clearly marked dishwasher-safe.

Thin plastic and disposable containers are another story.

High temperatures can cause them to warp or deform.

Whirlpool recommends checking the markings and placing dishwasher-safe plastic on the upper rack, while disposable plastics should not go through the dishwasher.

If you’re unsure, don’t gamble with a container that could melt or change shape.

11. Items with glued handles

Here’s one people often overlook.

Some knives and kitchen utensils have handles attached with adhesives.

The heat inside a dishwasher can weaken certain adhesives over time.

Whirlpool specifically warns about hollow-handle knives whose handles may be attached with adhesives that can loosen during dishwasher washing.

The item might survive dozens of cycles without a problem.

Then one day the handle starts moving.

That’s why the manufacturer’s care instructions matter more than simply asking whether an object is made of metal.

12. Gold-colored or gold-trimmed items

Gold decoration and aggressive dishwasher conditions aren’t always a good combination.

Gold-colored flatware can discolor, and gold leaf or decorative trim on china can fade or lose its finish.

Whirlpool specifically recommends keeping gold-colored flatware out of the dishwasher and warns that gold leaf on china can discolor or fade.

If you have a special set that only comes out for holidays, hand washing is a much safer habit.

13. Silver and silver-plated pieces

Silver is another material where dishwasher rules can get complicated.

Some silver and silver-plated items may technically tolerate dishwasher washing under specific conditions, but detergent, food residues and contact with other metals can contribute to tarnishing or other reactions.

Whirlpool generally recommends hand washing silver and sterling silver to protect the finish.

If it’s something valuable or sentimental, don’t let convenience make the decision.

14. Pewter, brass and bronze

These older-looking metals can react badly to dishwasher conditions.

High temperatures and detergent can discolor or pit the surface.

Whirlpool specifically lists pewter, brass and bronze among materials that should not go into the dishwasher.

So that decorative serving piece from your grandmother’s kitchen?

Keep it out.

15. Antique or hand-painted decorations