Sharpen Up

This Is What a Dishwasher Actually Does to Your Knife

updated Dec 31, 2020
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(Image credit: Maria Siriano)

The day you bought a dishwasher, you probably thought you gave up hand-washing forever, right? Not so fast. Not everything can or should go in the dishwasher, including the kitchen tool you probably use every single day: your knife. It’s precious, it’s expensive, and your dishwasher is slowly killing it.

We have six knife experts (our “cutting board” of experts, if you will) who we’ve turned to again and again for advice. They’re not always in complete agreement, but with regards to your blades and your dishwasher, they are 100 percent united. “Please, please do not put your knife in the dishwasher,” pleads Josh Moses, co-founder at Misen. Taylor Erkkinen, co-founder of Brooklyn Kitchen, was even more blunt: “I don’t know what you’re doing with your knife that you can’t just clean it off.”

Other things that shouldn’t go in the dishwasher: 11 Things You Probably Shouldn’t Put in the Dishwasher

What Actually Happens to Your Knife During the Wash Cycle

First, there’s the heat and humidity to contend with. You probably don’t love to be hot and wet; your knife doesn’t either.

“The high temperature and moisture of the dishwasher can seriously damage both the steel and the handle,” explains Moses. This is especially true if your blade is carbon steel (more likely to rust) or has a wood handle. (You don’t put your wooden spoon in the dishwasher, right?).

Next, there’s the turbulence. (Again, do you like to be jostled about?)

“The water jets in the dishwasher can cause the knife to knock into whatever else you have it in the dishwasher with, and can damage the edge,” says Moses. “It’s a good way to ruin a knife quickly.” And, by the way, ceramic knives are at an even greater risk, because they are so brittle. One cycle can chip the blade or snap it in two.

Then there’s the detergents, which can be just as dangerous as the machine itself, causing knives to dull or discolor.

Finally, your knives aside, there’s the matter of everything else that goes in the dishwasher, including your fingers when you’re unloading. Your knives can scratch cups, plates, and even the actual machine. Point them down, they can damage utensil baskets; point them up and you risk an injury.

So, How Should You Wash Your Knives?

For most knives, hand-washing in hot, soapy water will do — or even just hot water. “Hot water — just tap water. Not boiling water,” advises Eivin Kilcher, cookbook author and star of Discovery’s Alaska: The Last Frontier. “Sometimes, if we have to use soap, I will oil them,” he adds.