Cleaning

15 Things You Should Never, Ever Put in the Dishwasher

Read this before your next cycle.

September 11, 2019
Photo by Rocky Luten

My motto when shopping for home goods is, “If it doesn’t go in the dishwasher (or washing machine), it doesn’t go in my house!” Washing dishes is one of my least favorite chores, so I do my absolute best to keep hand wash-only items out of my cabinets.

But despite my efforts, there are still a number of kitchen essentials I end up hand-washing, typically because I didn’t read the fine print when I bought them. (Seriously, who knew box graters shouldn’t go in the dishwasher?)

If you’re guilty of skipping the fine print, too, you might not realize a few core kitchen items are supposed to be hand-washed. To keep your tableware, cookware, and other kitchen accessories in top shape, make sure to keep these 15 things out of the dishwasher:

1. Cast Iron

Hopefully this doesn’t come as a shock, but your cast iron pans should never go in the dishwasher. In fact, you shouldn’t even use soap on them when you can help it. Soaps and abrasive sponges can damage the finish and seasoning of your precious pan, so stick to using coarse salt to scrub it down.

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“I have never experienced or heard of this. I wonder what strange mix of dishwasher type, soap choice, and water characteristics make that happen!?”
— M
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If you do accidentally wash your cast iron pan with soap (my roommates have done this to me before), don’t stress. It’s easy enough to reseason cast iron—you just need to oil it up, and bake it in the oven.

2. Nonstick Pots & Pans

The reason it's said you should never use metal utensils on nonstick pans is that they can damage the finish, ruining the effectiveness of the nonstick surface. The same thing can happen if your pots and pans get banged around in the dishwasher—the surface can get scratched, shortening its lifespan.

3. Crystal

Crystal glasses are delicate, and the high heat and/or water jets in your dishwasher can cause chips or cracks. Even if they do make it through the cycle, your glasses may develop a cloudy residue over time—so stick to hand-washing crystal and fine wine glasses.

4. Wooden Cutting Boards & Utensils

Wood and dishwashers just don’t mix. The heat of the dishwasher can cause wood to warp, and the drying cycle can make it crack. So please, keep your wooden cutting boards and utensils out of the dishwasher.

5. Insulated Travel Mugs

Most travel mugs have a special vacuum seal between the inner and outer shells, and this seal can be ruined if you put the cup in the dishwasher. Not only will this compromise the effectiveness of your favorite mug, but you may also get water in the walls that sloshes around as you drink.

6. Copper Pans

Copper is prone to tarnishing, and the harsh conditions of the dishwasher can ultimately ruin the shine of your beautiful copper pots and pans. Given that they’re typically quite pricey, I think it’s worth hand-washing to protect your investment.

7. Your Best Knives

Of course you can put your butter knives in the dishwasher, but you might want to think twice about putting good kitchen and prep knives through the cycle. Why? The harsh conditions of the appliance can dull the edges of blades, forcing you to sharpen them more frequently. It can also cause carbon steel and other materials to rust.

8. Graters

There are two reasons to wash graters by hand. First, similar to with knives, the dishwasher can dull graters' blades. And second, chances are, a dishwasher won’t be able to get all the particles out of their little holes, so you’re better off doing it by hand anyway.

9. Aluminum Pans

Both aluminum cookware and disposable aluminum trays will become discolored when put into the dishwasher, if not sealed in some way. The metal can react with water and air in a process called oxidation, and becomes covered in a dark film that then rubs off on other items.

10. Pressure Cooker Lids

While technically the top of your Instant Pot is dishwasher-safe, it’s not the best cleaning option, as there are a number of important components in the lid of a pressure cooker. For instance, there are values that can get clogged with food particles, as well as seals that may be damaged by the dishwashing chemicals—both of which will shorten the lifespan of your appliance.

11. Milk Glass

The pure white hue of milk glass makes it a treasured collection piece for many, and it’s important to learn how to care for this material properly if you want it to last. Milk glass can take on a yellow tint if put in the dishwasher too many times, so you’ll want to wash it carefully with a gentle cloth and soapy water.

12. Thin Plastic Containers

Unless you know for a fact that a plastic container is dishwasher-safe, I’d recommend scrubbing it down the old-fashioned way. Thin plastic will sometimes melt or warp in the dishwasher, rendering the container useless—a lesson I’ve learned the hard way.

13. Pop-Top Storage Containers

Airtight storage containers are a must-have in any pantry, but when it comes time to clean them, the dishwasher is a gamble. Many say they’re dishwasher-safe, but the gaskets can warp and seals can break down if you wash them frequently.

14. Family Heirlooms

In general, it’s best to leave anything precious that's missing cleaning instructions out of the dishwasher. This applies to fine china, your grandmother’s favorite mixing bowl, or whatever else you hold near and dear. Don’t risk it getting dinged in the dishwasher!

15. Items with Labels or Adhesives

If you’ve ever put an empty pasta sauce jar through the dishwasher (guilty), you know that the label comes out a torn, soggy mess. Not only will the hot water ruin the label, but the pieces that flake off can clog your dishwasher’s filter, as well.


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40 Comments

Scott September 19, 2019
In #10 you say: "...there are values that can get clogged with food..." I think you mean "valves", not "values". :-)
 
Maria O. September 16, 2019
Well, our 40+ year old box grater, Microplane, and mesh colander all go into the dishwasher without problem. My brother-in-law washed old jumper cables in his machine!
 
Preesi J. September 16, 2019
I put everything I can in there. I just dont care.
 
johnstick208 September 16, 2019
Some really useful slides here. I've been looking for something like this to help with a
research piece I've been working on. Cleaners in Dubai
 
Carol September 15, 2019
Silverware, plate or sterling, does not belong in the dishwasher. Hastens tarnish, just as w copper.
 
Lune September 15, 2019
Apparently, computer keyboard can go in the dishwasher... many moons ago, a co-worker spilled a liquid on it and was told (light heartily) to put it in the dishwasher. Co- worker came back next morning with freshly "dishwashed" keyboard, plugged it in and it worked!
 
timhood September 16, 2019
I washed a keyboard that a co-worker had spilled Coke and let it dry because she was afraid to tell anyone. I partially disassembled it and hand-washed it in the sink. I wouldn't expect a keyboard to last as long after it gets washed, especially if the water is hard. I definitely wouldn't use detergent or a heated dry cycle, but there's not much to lose with a coffee- or soda-covered keyboard.
 
Anne J. September 14, 2019
Heavy glass serving pieces such as from Pier 1. They will crack or break as they will expand unevenly in the high heat. I’m still hand washing 4 which I bought on sale $9 a piece in 1998, they are lovely and intact, I have rescued them from the dishwasher innumerable times after helpful guests unknowingly put them in there. I can’t replace them and they are all different colors lovely for bean salads and other salads. Also ideal for washing and rinsing cashmere sweaters strangely enough, just the right size for one. Something to not put in the washing machine.
 
timhood September 12, 2019
#3: A modern, quality dishwasher will have a special setting for crystal and can wash them just fine, as it automatically adjusts water temperature and other settings.

Any glassware can become etched (e.g. cloudy) if too much detergent is used in the wash. Modern detergents are much more effective and less is needed than detergents from years ago. This is especially true if the water is soft.
 
Anne J. September 14, 2019
I respectfully disagree. If you truly have fine crystal, and I’m speaking of Baccarat or it’s ilk, then you better have deep pockets if you put them in your dishwasher. They will be damaged subtly over time. The cleaning process is similar to sandblasting, obviously not as strong but abrasive. My fine crystal gets washed in the sink lined with dish cloths which is why it lives in the cupboard and I use cheap crystal almost always.
 
timhood September 16, 2019
I agree that I probably wouldn't wash expensive crystal in the dishwasher--not because it couldn't handle it, but because of the cost/benefit risk. The crystal/china cycle in the dishwasher is specifically designed for the purpose, including a lower wash temperature. The real potential for damage is not from the dishwasher, but the user. People use too much detergent, particularly if they don't have hard water. The excess detergent is what causes etching on glassware, not the stream of water from the sprayers.
 
timhood September 12, 2019
#7: Please stop repeating this tired trope. It's almost as bad as the "change your oil every 3,000 mile myth". Not one person has ever been able to cite any study, test or verifiable information to support this claim. Yet people just keep repeating what they've heard from somewhere else, assuming it's true. Meanwhile, I have 29-year old knives that have been dishwasher-cleaned since day one and I sharpen them with no extra frequency. I believe this myth was a variation from when you weren't supposed to wash knives because they had wood handles. Mine are plastic.
 
BirdFeeder September 12, 2019
Another one that bothers me the most: putting kitchen utensils (including knives) with glued or rivetted handles in the dishwasher. Between the heat and the hypochlorite soaps, they become loosened and fall apart! I understand the need &/or convenience of "throwing everything into the dishwasher", but THERE IS A LIMIT to what utensils such as these can take (especially, repeatedly)!!
 
Albert F. September 11, 2019
All Yeti Tumblers and Ramblers are Dishwasher safe. It’s one if it’s features.
 
Fred B. September 11, 2019
To me this article is a huge DUH! Every instance listed is simply a matter of using your common sense. I'm retired and my wife still works so I do most the house work including dishes. Never have I done any of these faux pas and I didn't take home ec classes in school to know how to do dishes.
 
Drea September 11, 2019
Regarding adhesive labels on jars, I had a label come off a jar in the dishwasher and when I found it had scorch marks from the heating elements. Thank goodness a fire didn’t start.
 
Molly September 11, 2019
She really should have done her research. If an “abrasive sponge” is too harsh on your cast iron pans, you think scouring with “coarse salt” is really okay? Lodge, huge manufacturer of everything cast iron says “Don’t use salt on your cast iron!” Not only is it rough, the chemical makeup also pits your pans. I grew up thinking we should rarely use soap but ALL manufactures say it’s okay. Her other claims seem a little suspect too...I’ve washed aluminum pans for 30 years- no discoloration. Travel mugs, “could” get water in lining- ours never have, my cheese grater is sharp as ever after 6 yrs. in the dishwasher. The answer to something that washes fine but can’t take the heat of the dishwasher is-TAKE IT OUT BEFORE THE DRY CYCLE!
 
Richard D. September 11, 2019
There are more wives tales about cast iron than truths. Soap is fine, just be sure to completely dry it after washing. You're gonna oil it the next time you cook in it in all likelihood, so don't sweat the 'seasoning' if you did it when you bought it.
 
timhood September 16, 2019
Yeah, salt and iron aren't friends. I would never try that, either.

Aluminum pots and pans that are anodized are fine in the dishwasher. Untreated aluminum (example: aluminum scoops you might use for rice and flour or an aluminum ice cream server) reacts with the detergent, will turn a dark grey and cast off an aluminum oxide residue.
 
Uncle J. September 18, 2019
Yup. That happened to my ice cream server. Looks awful.
 
timhood September 18, 2019
With some steel wool, you can scrub off that oxidation and at least get it to where your vanilla ice cream doesn't turn grey. It'll never get to like new as it will still be darker grey, but at least it will be usable.
 
Firemark H. September 11, 2019
Sex Toys!

I had a short lived roommate experience where a young woman loaded all her toys in the top rack to sanitize them.
 
Annet September 11, 2019
You mean never if you have a roommate haha (agreed!). It’s great if you live alone!
 
Firemark H. September 13, 2019
I hope I never have dinner at your place!!
 
timhood September 16, 2019
Please, please, please tell us that at least there were no other dishes in there! 😄 Maybe you could have suggested the washing machine. 😄
 
Lele G. September 11, 2019
Italian pottery! I collect lovely Italian plates and bowls from Deruta and if placed in a dishwasher the clay expands and cracks the glaze and often the dish. One time a well meaning dinner guest asked to help clean up, and it didn’t occur to me that all of my cups plates and bowls would go into the dishwasher.. lesson learned sadly. All but one cracked.
 
Katie V. September 11, 2019
(Did I read too fast and miss it?) Don’t put sterling silver or silverplate in the automatic dishwasher. It ruins the finish. Use a gentle soap like Bonners to clean silverware.
 
Amy B. September 12, 2019
Our sterling has been used every day for more than 46 years. It goes into the dishwasher. However, the sterling handled knives do NOT go into the dishwasher - their handles are glued to the stainless blades. Dishwasher heat will destroy the adhesive bond.
 
Anne J. September 14, 2019
It will also remove the rhodium which is the bright part of sterling silver and white gold. The heat is too hot. Your silver cutlery is fine if you are fine with it.
 
Alix September 15, 2019
Have been using my sterling for every meal - for more than 50 years. All of it goes into the dishwasher. All of it, including the knives, is just beautiful!
 
M September 11, 2019
Just how much soap are your roommates using on your cast iron that you need to re-season it? Soap on a cloth or sponge shouldn't break through the seasoning.
 
Molly September 11, 2019
According to Lodge & Faberware, you are correct M! She should have done her research. Go to the websites of the company’s who MAKE the pans. Wealth of accurate info there.
 
S September 11, 2019
Laundry detergent!!! Has anyone else done this: disastrous!
 
Bruce C. September 11, 2019
The bowl and utensil you used to scramble eggs, unless you want everything that comes out of your dishwasher to smell like wet dog.
 
M September 11, 2019
I have never experienced or heard of this. I wonder what strange mix of dishwasher type, soap choice, and water characteristics make that happen!?