Can You Put a Knife in the Dishwasher? Here's Why We Don't Recommend It

When you're cleaning up after dinner, it's tempting to put your knife in the dishwasher with everything else. We'd rather you took a minute and washed it by hand.

Can dishwashers ruin knives? Not always in one cycle, but they're hard on them. A dishwasher puts a knife through long stretches of moisture, heat and detergent, often while it bumps against dishes and metal utensils. That combination damages the edge, encourages corrosion, and takes a toll on the handle.

A knife might come through one cycle looking fine. It's the repeated trips where the damage starts to show.

What a dishwasher does to the cutting edge

A thin cutting edge does its best work against what you're cutting. Contact with a plate, another knife or a metal rack dulls it, rolls it or chips it.

Wedging the knife somewhere it won't move cuts down on that contact, but it does nothing about the moisture, detergent and heat working on the rest of the knife.

An exposed sharp blade is also a hazard for whoever reaches in to unload.

Stainless steel can still corrode

Stainless steel resists corrosion. It isn't immune to it.

A dishwasher can leave a blade with discoloration, rust spots or pitting, depending on the steel, the detergent, the water and how long the knife sits there. Moisture also collects around handle joints and other places that are hard to see or dry.

Carbon steel needs even more attention. A wet wash cycle followed by hours in a closed, damp dishwasher gives corrosion all the opportunity it needs. We go into the difference between the two in carbon steel vs. stainless steel, and which knife is right for you.

Whether your blade is carbon or stainless, washing and drying it by hand puts you in control of those conditions.

The handle has to survive the cycle, too

People tend to focus on the blade, but the handle is another good reason to keep a knife out of the dishwasher.

Wood absorbs moisture, swells, then shrinks as it dries. Repeated exposure raises the grain, wears the finish, and can lead to cracks or gaps. Natural materials such as antler and bone suffer too.

Stabilized wood resists moisture better than untreated wood, but that doesn't make the finished knife dishwasher safe.

Synthetic materials such as G10 and Micarta generally handle moisture better. Still, a durable handle material is only part of the knife. The adhesives, liners, fasteners and joints between materials all have their own limits. Heat and repeated wet and dry cycles stress that assembly over time, and a handle that looks solid from the outside can still have places where moisture gets in.

Can dishwashers ruin a knife's heat treatment?

No. A normal household dishwasher doesn't get anywhere near the temperatures used to temper a knife blade, so the heat treatment isn't the concern.

The real concerns are corrosion, damage to the edge, and wear on the handle and how it's put together.

That distinction matters. There are enough practical reasons to wash a knife by hand without adding one that doesn't apply.

How we recommend washing your knife

You don't need an elaborate routine.

1. Wash it after use. Use warm water, mild dish soap and a soft sponge or cloth. Keep your fingers clear of the edge and don't run them along it.
2. Don't leave it soaking. Wash the knife on its own instead of dropping it into a sink full of dishes, where someone could reach in without seeing it.
3. Rinse and dry it thoroughly. Pay attention to where the blade meets the handle and to any exposed joints.
4. Put it away dry. Store it securely with the edge protected. For a carbon steel blade, add a light coat of oil when it needs it, especially before long storage, and use an oil that's safe for food contact if the knife is used for food.

If your knife has a leather sheath, make sure both are dry before they go together, and store the knife outside the sheath for long stretches. Here's how to care for a leather knife sheath. The full routine for the knife itself is in our knife care guide.

What if your knife already went through the dishwasher?

One accidental cycle doesn't mean the knife is ruined.

Take it out, dry it thoroughly and look it over. Check the blade for rust, discoloration and edge damage. Check the handle for cracks, swelling, gaps or movement.

If the handle has loosened or you find a crack in the blade, stop using the knife and have it inspected. If it's one of ours, get in touch and we'll take a look.

That goes for every knife in our kitchen collection: wash it by hand, dry it, and it'll be there for the next dinner.