A dishwasher can be one of the most useful appliances in your kitchen. Load the dirty dishes, add detergent, press a button, and let the machine handle the hard work.
But there’s an important catch:
Not everything in your kitchen is dishwasher-safe.
Dishwashers combine hot water, powerful detergents, high-pressure spray, and heat during drying. That’s excellent for many everyday plates, glasses, and utensils, but it can damage certain materials surprisingly quickly.
Some items may lose their finish. Others can warp, crack, rust, become dull, or deteriorate after repeated dishwasher cycles.
And in some cases, putting the wrong object inside can create problems for the dishwasher itself.
Before loading your next cycle, here are 8 things that are generally better washed by hand.
1. Wooden Cutting Boards and Wooden Utensils
Wooden cutting boards, spoons, salad servers, and other wooden kitchen tools are usually better kept out of the dishwasher unless the manufacturer specifically states otherwise.
Why?
Wood absorbs moisture.
Inside a dishwasher, wooden items are repeatedly exposed to hot water and then heat during the drying process. Over time, that combination can cause wood to swell, dry unevenly, warp, split, or crack.
The dishwasher may also gradually strip away oils and finishes that help protect wooden kitchenware.
What to Do Instead
Wash wooden utensils and cutting boards by hand using warm water and dish soap.
Don’t leave them soaking unnecessarily.
After washing, rinse them and allow them to dry thoroughly.
Some unfinished wooden boards also benefit from periodic treatment with a food-safe mineral oil according to the manufacturer’s care instructions.
2. Cast-Iron Cookware
Your heavy cast-iron skillet may seem almost indestructible, but the dishwasher is not its friend.
Traditional cast-iron cookware develops a protective layer of seasoning through repeated cooking and oiling.
Dishwasher detergent and prolonged exposure to water can damage that seasoned surface and encourage rust.
You may open the dishwasher expecting a clean skillet only to discover that the finish has deteriorated.
What to Do Instead
Follow the care instructions provided by the cookware manufacturer.
For traditional seasoned cast iron, hand-washing is generally recommended.
Dry it thoroughly after cleaning because leaving cast iron wet can promote rust.
If necessary, apply a thin layer of cooking oil afterward to maintain the seasoning.
3. Good Kitchen Knives
Throwing your chef’s knife into the dishwasher may save a minute at the sink, but it isn’t necessarily good for the knife.
High-quality knives can be damaged by harsh dishwasher conditions.
The blade can knock against racks, utensils, and other objects during the wash cycle, potentially dulling or damaging the edge.
Certain knife handles can also deteriorate after repeated exposure to heat and moisture.
There’s another practical problem: a sharp knife hidden inside a loaded dishwasher can be a cutting hazard when unloading it.
What to Do Instead
Wash good knives carefully by hand soon after using them.
Use warm water, mild dish soap, and a soft sponge or cloth.
Dry them promptly before storing them safely.
And never leave sharp knives hidden beneath soapy water where someone could accidentally grab the blade.
4. Copper Cookware
Beautiful copper pots, pans, mugs, and utensils can be expensive, and their appearance is one of the main reasons people buy them.
A dishwasher may affect that appearance.
Strong detergents and repeated dishwasher cycles can cause copper surfaces to discolor or lose their polished finish.
If you want your copper cookware to maintain its characteristic appearance, hand-washing is generally the safer option.
What to Do Instead
Use the cleaning method recommended by the manufacturer.
Usually, gentle hand-washing with appropriate products is preferable to aggressive cleaning.
Remember that decorative copper pieces and copper cookware intended for cooking may have different finishes, so always check the specific care instructions.
5. Aluminum Items That Aren’t Labeled Dishwasher-Safe
Aluminum requires a little more explanation because not every aluminum product behaves the same way.
Some modern aluminum cookware may be specifically designed for dishwasher use.
Other aluminum items can react with dishwasher detergents and become dull, darkened, spotted, or discolored.
Bare aluminum is particularly vulnerable.
What to Do Instead
Check the manufacturer’s label.
If an aluminum pot, pan, baking sheet, or utensil isn’t specifically marked dishwasher-safe, hand-washing is the cautious choice.
This is also a good general rule for unfamiliar cookware materials:
When you’re unsure, check before putting it in the dishwasher.
6. Nonstick Cookware — Unless the Manufacturer Says It’s Dishwasher-Safe
This one isn’t completely black and white.
Many modern nonstick pans are marketed as dishwasher-safe.
However, that doesn’t necessarily mean dishwashing is the best method for maximizing the life of every nonstick surface.
Repeated exposure to aggressive detergent, high temperatures, and contact with other objects can contribute to wear on some coatings.
Older or already-damaged cookware deserves particular care.
What to Do Instead
Check the manufacturer’s instructions for your specific pan.
If hand-washing is recommended, use a soft sponge and ordinary dish soap.
Avoid abrasive scrubbers that could scratch the cooking surface.
If the coating is badly peeling, flaking, or otherwise deteriorating, follow the manufacturer’s replacement guidance rather than attempting to restore it with aggressive cleaning.
7. Delicate China, Hand-Painted Dishes and Gold-Trimmed Pieces
That beautiful plate inherited from your grandmother probably shouldn’t be treated like an ordinary dinner plate.
Fine china, hand-painted ceramics, antique dishes, and pieces decorated with gold or silver trim can be vulnerable to dishwasher conditions.
Repeated cycles may fade decorative patterns or damage metallic detailing.
Even if an item survives one wash, repeated dishwasher cleaning may gradually affect its appearance.
What to Do Instead
Wash delicate or sentimental pieces individually by hand.
Use mild dish soap, warm water, and a soft cloth or sponge.
Handle them carefully and avoid sudden temperature changes.
For antique or particularly valuable pieces, consider obtaining specialized care advice.
8. Insulated Travel Mugs and Vacuum Containers — Unless They’re Specifically Dishwasher-Safe
Reusable insulated bottles and travel mugs are another category where the manufacturer’s instructions matter.
Some newer models are completely dishwasher-safe.
Others aren’t.
Depending on the construction, repeated dishwasher exposure can affect finishes, seals, lids, or components designed to maintain insulation.
Water can also become trapped in complicated lid mechanisms.
What to Do Instead
Look for the dishwasher-safe symbol or check the manufacturer’s instructions.
If the item isn’t dishwasher-safe, wash the body and lid according to the recommended method.
Pay particular attention to removable seals and gaskets, where residue can accumulate.
Bonus: Never Put Ordinary Dish Soap in Your Dishwasher
This mistake deserves special attention.
Dishwasher detergent and ordinary hand-washing dish soap are not interchangeable.
Regular dish soap is designed to produce lots of suds.
Inside a dishwasher, the machine’s spraying action can create an enormous amount of foam.
That foam may escape from the dishwasher and spread across the kitchen floor.
If you’ve ever seen a picture of a dishwasher surrounded by mountains of bubbles, ordinary dish soap is often the type of mistake being illustrated.
What Should You Use?
Use only detergent specifically formulated for automatic dishwashers.
That may include dishwasher tablets, pods, powder, or gel, depending on your machine and its manufacturer’s recommendations.
What About Plastic Containers?
Plastic deserves its own mention because there’s no universal rule.
Some plastic containers are dishwasher-safe.
Others can warp or deteriorate when exposed to high temperatures.
Always look for the dishwasher-safe marking.
When the manufacturer recommends placing an item only on the upper rack, follow that instruction because the position of heating components varies among machines.
If there’s no information available and the container is important to you, hand-washing is the safer choice.
Can Stainless Steel Go in the Dishwasher?
Many everyday stainless-steel utensils and cookware items can be dishwasher-safe.
But once again, check the manufacturer’s instructions, especially for expensive cookware or items containing multiple materials.
For example, a pan may have a stainless-steel body but a handle or decorative component requiring different care.
What About Crystal Glassware?
Fine crystal can be more delicate than ordinary drinking glasses.
Depending on the manufacturer and type of crystal, dishwasher heat, detergent, or physical contact with other items may damage it or cause cloudiness over time.
If you’re dealing with valuable crystal, hand-washing is usually the more cautious approach unless the manufacturer explicitly approves dishwasher cleaning.
Why Dishwasher Detergent Can Be Hard on Certain Materials
Automatic dishwasher detergent has a difficult job.
It must remove grease, dried food, starches, and other residue without someone physically scrubbing the dishes.
The dishwasher also relies on hot water, spray pressure, and controlled washing and drying cycles.
Those conditions are perfectly appropriate for items designed to tolerate them.
But materials such as unfinished wood, seasoned cast iron, delicate decorations, and some specialty finishes require gentler treatment.
That’s why an item can technically become “clean” in a dishwasher while simultaneously becoming damaged.
The Dishwasher-Safe Symbol Matters
One of the easiest ways to avoid mistakes is also one of the most frequently ignored:
Read the label.
Manufacturers generally provide care instructions for cookware, storage containers, bottles, kitchen appliances, and utensils.
If an item says:
Dishwasher Safe — follow any additional placement instructions.
Top Rack Only — don’t put it elsewhere in the machine.
Hand Wash Only — keep it out of the dishwasher.
When there is no label and you aren’t sure, washing the item by hand is usually safer than experimenting with something expensive or sentimental.
Don’t Forget Small Appliance Parts
Blender jars, food processor bowls, mixer attachments, air-fryer accessories, coffee-machine components, and similar items can be especially confusing.
Some removable components may be dishwasher-safe while other parts from the same appliance aren’t.
Never assume that because one component can go into the dishwasher, every removable component can.
And electrical bases, motors, power cords, and other electrical components should never simply be submerged or placed in a dishwasher.
Consult the appliance manual for cleaning instructions.
How to Protect Your Dishwasher
Taking care of what goes into your dishwasher isn’t only about protecting dishes.
Before loading the machine:
Scrape large pieces of food into the trash or compost.
Make sure small objects cannot fall through the racks.
Don’t allow utensils to obstruct the spray arms.
Use the correct type and amount of dishwasher detergent.
Check that fragile items aren’t touching objects that could strike them during the cycle.
And don’t overload the machine.
Good loading allows water and detergent to reach the surfaces they’re supposed to clean.
A Simple Rule That Can Save Expensive Kitchenware
When you’re standing in front of the dishwasher wondering whether something belongs inside, ask yourself three questions:
Is it labeled dishwasher-safe?
Could heat, moisture, or strong detergent damage it?
Would I be upset if its finish, shape, or coating changed?
If you’re uncertain about any of those questions, spending a minute washing the item by hand may save you from replacing it later.
The Bottom Line
Dishwashers are incredibly convenient, but they’re not designed for every object in your kitchen.
Wooden utensils, traditional cast iron, quality knives, delicate china, copper, certain aluminum products, some nonstick cookware, and some insulated containers are generally better candidates for careful hand-washing unless their manufacturers specifically state otherwise.
And one rule deserves repeating:
Never substitute ordinary hand dish soap for automatic dishwasher detergent.
A few extra minutes of proper care can help your cookware, knives, dishes, and kitchen tools last much longer.
Before putting an unfamiliar item into your next load, check its care instructions.
Your dishwasher — and your favorite kitchenware — may thank you.