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What Makes an Item ‘Dishwasher Safe’?

A woman filling the dishwasherat home in her kitchen.

We’ve all purchased tons of items the manufacturer claims are “dishwasher safe.” However, what does it take to make something “safe” to go in the dishwasher, and why can’t some other items go in there at all?

We’re all used to running just about everything through the dishwasher, and that’s because most products—especially kitchenware—have that ever-sought-after label of being “dishwasher safe.” But how do they earn that label? We decided to find out!

What Does “Dishwasher Safe” Really Mean?

Scotch-brite sponge placed on the top rack of a dishwasher.

The term “dishwasher safe” essentially describes any item that can withstand moisture, high temperatures, and strong detergents during the dishwashing cycle. Materials that will rust, melt, or warp from the scalding water can’t be put in this handiest of appliances.

If you have the owner’s manual for a product, somewhere in there, it should state whether the item is dishwasher safe or not.

But what if you tossed the manual, or didn’t get one in the first place? No problem! You can also check the product’s description on the manufacturer’s website. You might even be able to download a PDF of the owner’s manual if you’ve lost yours.

If all of those measures fail, however, we’ll give you a quick rundown of materials and items that generally can (and cannot) go in the dishwasher.

Which Materials Are Generally Considered Dishwasher-Safe?

Not all products come with a manual, and some might have been made way before the internet even existed, so there’s no way to search for it online. If this is the situation in which you find yourself, you don’t automatically have to resort to handwashing that item, as long as you know what it’s made of.

Generally, anything made of the following materials is considered safe to put in the dishwasher:

  • Ceramic: Dinnerware, including coffee mugs, saucers, and small bowls can all go on the top rack, while large plates and bowls go on the bottom.
  • Silicone: Things like trivets, ice cube trays, and baking mats will all be safe on the top rack.

Silicone Baking Mat

Dishwasher-safe and super convenient on baking days.

GORILLA Plastic Cutting Board

Won't warp or melt in the dishwasher.

  • Sturdy glass: You should avoid putting anything made of delicate glass, like stemware, in the dishwasher. However, feel free to put mixing bowls, bakeware, or even your microwave’s spinning plate, in there for a spin.
  • Scrub brushes and sponges: These quickly pick up tons of bacteria, as they remain damp or wet most of the time. Luckily, your dishwasher can disinfect these little guys in one cycle.

Scotch-Brite Srub Sponges

Yes, you can run these through the dishwasher and reuse them.

If you aren’t 100% sure a particular item is dishwasher-safe, check the bottom—it might have a label. Again, you can also look the item up online to get more details. However, when in doubt, hand-wash!

Which Items Should Never Be Put in the Dishwasher?

Someone holding a broken wine glass over the bottom rack of a dishwasher.

Unfortunately, there are some items that should never be put in the dishwasher. Some are just far too flimsy. The scalding hot water might melt or warp them, or the moisture or harsh detergent might damage them.

Generally, you should avoid placing these items and materials in the dishwasher:

  • Knives: Many don’t know this, but they can damage your dishwasher’s racks. The blades will also dull much faster, so stick to hand-washing these.
  • Wood or bamboo cutting boards: The moisture and constant water exposure will crack these, so always hand-wash and avoid soaking them.
  • Aluminum: You can reuse those disposable turkey and baking pans, but dishwashing detergent will discolor them.
  • Insulated mugs: Your dishwasher will damage the seal and insulation.
  • Copper: Avoid discoloring that expensive set of cookware and wash it by hand instead.
  • Delicate glass: Sturdy glass is okay, but anything thin or delicate is probably best washed by hand to avoid breakage. And trying to clean broken glass out of your dishwasher is a nightmare.
  • Thin plastic: Anything flimsy, like spreadable butter tubs, will likely melt in the dishwasher from the high heat, even if you place them on the top rack. Always wash items like this by hand.
  • Sentimental items: Heirlooms are irreplaceable, so the last thing you want to do is break or discolor one by running it through the dishwasher. Gently hand-washing these types of items is always the safest bet.
  • Cast iron: While many brands market their enameled cast-iron cookware as dishwasher safe, it’s still best to wash these pieces by hand to avoid chipping and rusting them. Non-enameled cast iron should never be placed in the dishwasher, as the detergent and water will ruin the seasoning (the layer of fat that protects it).

Hopefully, this clears up any questions you had about what will (or won’t) be safe in the dishwasher. In the future, you can always double-check before purchasing an item if you prefer to live in a dishwasher-safe-only world.

If you’ve always been curious what the heck “dishwasher safe” actually means, congratulations! You now know the secret. While we couldn’t possibly add every single item or material that is or isn’t dishwasher safe, these lists should at least give you a starting point. Feel free to print them out and stick them on the fridge . . . or how about the dishwasher?

Emilee Unterkoefler Emilee Unterkoefler
Emilee Unterkoefler is a freelance food writer, hiking enthusiast, and mama with over ten years of experience working in the food industry. Read Full Bio »
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