3 Reasons Why You Shouldn't Put Your Knives in the Dishwasher

Knives are one of the most essential tools in the kitchen, and caring for them properly is key to their longevity, functionality and your own safety.

When cooking, it really doesn't matter if you are practically a professional chef or a serious newbie, using a knife is going to be a big part of your culinary practice. But whether you have invested in a serious set of knives or are just making do with a ragtag assemblage of necessary blades, caring for them properly is essential.

Not only does the proper care of knives keep them sharper for longer, but it also prevents them from becoming dangerous! A dull blade can catch on food and slip and needs more force to use, which makes it less stable and more likely to turn on you. Surprisingly, while dull knives have trouble getting through tomato skin, they will have no problem at all getting through your skin.

So how do you care for your knives? Obviously, regular sharpening is important, whether you have it done by a pro or invest in a great sharpener. Storing them properly is also important—a knife block works great, as does a magnetic knife strip.

But what about washing them? Many people swear by hand-washing their knives, while others have no problem tossing them into the dishwasher. But are you unknowingly doing damage to your knives by washing them in the dishwasher? Let's dive into the details.

How Dishwashers Work

Dishwashers use a three-way punch to clean your dishes. First, water is heated and put through a series of sprayers to blast bits and pieces of food off of your dishes. It is helped in this process by the dishwasher detergent you use, which helps remove grease and has a sanitizing effect. Then more hot water is sprayed at force to rinse, removing all traces of detergent to ensure your dishes are safe to eat off of. And finally, the whole unit may heat up extra hot to dry everything off. If you choose to use a rinse aid, this can help prevent water spots and is an extra boost to the cleaning process.

What Are Kitchen Knives Made Of?

We chatted with Bobby Griggs, the vice president of Heritage Steel, which makes Hammer Stahl cutlery. He shares that knives are made from different types of material including stainless steel, carbon steel and ceramic. "There are competing factors when considering the construction of a knife, including the hardness of the steel, which affects how sharp or steep of an angler the edge [can be], the propensity of rust to form on the blade when considering washing, care and usage, and the elasticity of the material, which directly impacts the ease of resharpening," says Griggs.

So What Happens to Knives If You Wash Them in the Dishwasher?

You put just about anything you use to cook or eat in the dishwasher, so your knives can go in there too, right? Not so fast. "It is our belief that cutlery should never be put in the dishwasher for a whole host of reasons," says Griggs. Not only can the knife's sharp edge maim the inside of the dishwasher and even lead to the inside rusting, but the process can damage the knife itself. "Most good-quality cutlery has been heat-treated and tempered during the manufacturing process, creating the optimal hardness of the blade, and the super high heat in a dishwasher over time can alter this tempering, leading to the steel softening and making it more difficult to keep and resharpen the edge," Griggs explains. "And the dishwasher's heat and aggressive detergents can affect the handle of the knife, leading to damage over time." The knives can also bump up against other cutlery during the washing process, which can dull or even chip them or damage your other cutlery.

Ouch.

Is It Ever OK to Wash Your Knives in the Dishwasher?

Griggs says, "Kitchen cutlery should always be washed by hand, dried immediately and put away." But we are a little less proscriptive. Kitchen knives that are crafted entirely from metal will not suffer handle damage in the dishwasher. If you have a third rack in your dishwasher that allows you to segregate knives so that they do not bump into other things and are as far away from the heating element in the bottom of the unit as possible, that is a safer place to wash knives. Ultimately, if you do choose to wash your knives in the dishwasher, you will definitely need to sharpen them more frequently, and you may need to replace them more often.

Bottom Line

You really should wash your knife by hand, but if you are adamant about putting it in the dishwasher, knives made entirely of metal will be unlikely to suffer handle damage. And if you have a top rack on your dishwasher, put them there—it's farther away from the heating element, and you can better separate the knives from other items to lessen the opportunity for extraneous damage.