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Do Dishwasher Dull Knives?

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Last updated on September 26th, 2022 at 01:33 pm

Dishwashers allow us to throw in our dishes, pots, pans, and other kitchenware and wait for just a little time to have clean, sparkling tools, including knives which is essential tool for those who love to cook.

Since knives are precious, you want to do your very best to keep them in great shape. One may wonder, “do dishwasher dull knives”?

Washing knives in dishwashers can cause them to become dull in luster and sharpness. These can be as a result of the dishwasher detergent or powder used, which are mostly corrosive, the force of impact generated during the washing process that can cause abrasion to the surfaces of knives, frequent washing in a dishwasher, leaving the knives in the dishwasher for too long, unfavorable factors such as moisture generated during the washing process and washing knives of poor quality in a dishwasher.

Can You Put Stainless Steel Knives In the Dishwasher?

No, it would be best not to wash stainless steel knives in a dishwasher as it can cause them to become dull in appearance and sharpness.

Knives made with stainless steel are very popular and are an excellent choice as kitchen knives. Stainless steel knives are very durable, do not wear easily, and can be sharpened easily.

However, it would be best if you did not wash stainless steel knives with dishwashers for the following reasons:

1. Dishwasher powders or detergents are often corrosive, especially alkaline-based detergents.

2. Dishwashers wash by throwing water jets onto the loaded materials in them and spinning them within the machine.

This spinning motion of kitchen utensils loaded into the machine can cause the sharpened edges of knives to knock against other kitchenware loaded together with the knives and results in blunt surfaces of knives or even distorted shapes.

3. It is not safe. The sharp edges can cause injury by laceration when wrongly removed from the machine.

4. Depending on the material used to make the handle of the stainless knife, they can be damaged as the machine tosses the knives while in operation, corroded by harmful detergents, or damaged due to impact with stronger kitchen tools loaded together in the dishwasher.

5. Stainless steel is rust-resistant but can rust due to the damaging chemicals, moisture, and heat present in dishwashers, especially if placed in them for a long time.

Why Does a Dishwasher Dull Knives?

A dishwasher can dull knives because of the dishwashing chemicals used. The impact is caused when the machine is in use, unfavorable conditions like heat and moisture that can cause rust, using corroded materials together with knives, especially those made with carbon steel, and when left in the dishwasher for long after washing.

Consider some of these reasons.

1. High Pressure and Heat In Dishwashers

Dishwashers work by heating cold water and moving the hot water under pressure onto the materials loaded into the machine. The high-pressure results in a spinning movement of materials within the machine.

In some instances, this pressure hurls materials against each other, resulting in damage by impact from materials that cannot withstand the force. The heat also negatively affects knives.

2. Dishwasher Detergents

Some dishwasher detergents or powder contain a highly alkaline blend of several different salts that are harmful to knives. Some of these salts have chlorides which can dent knives and encourage rusting. Knives can become dull in luster and blunt when these types of detergents are used to wash them.

3. Effect of Moisture

Rust can develop on knives due to moisture generated after a wash in the dishwasher, especially when the knives are left inside for too long. Rust can cause knives to become dull.

4. Effect of Other Corroded Kitchenware

Washing knives together with other corroded items in dishwashers can cause them to become dull as the rust can easily spread to vulnerable knives, especially knives made with carbon steel.

5. Leaving Knives In Dishwashers For Too Long

The long knives are left inside a dishwasher, the higher the probability of them becoming blunt because while in the dishwasher, the heat and moisture produced can cause knives to become dull over time.

How to Prevent Dishwashers From Dulling My Knives?

It is not advisable to wash knives in a dishwasher; however, some persons may find using the dishwasher their only option. The dulling of the sharpened edges and the entire body of knives is not inevitable, but you can slow the process

a bit.

You should take the following steps if you must wash the knives with a dishwasher:

1. You should use a mild or chloride-free detergent.

2. It would help if you did not load knives into the dishwasher and other hard materials that can cause them to become blunt during the washing process.

3. You should not wash knives together with rusted kitchenware. Rust affecting other kitchenware can easily spread to the metal-based knives and cause them to become dull either in luster or sharpness or both.

4. It would help if you loaded knives properly in an arranged manner within the dishwasher with the blunt side placed upwards.

5. You should not leave the knives in the dishwasher for long after a wash cycle is complete to avoid moisture settling on them and initiating a rust process, especially for knives made with carbon steel.

6. It would be best to quickly dry knives with a clean, dry cloth to avoid encouraging the reactions that result in rust.

Are there other ways of cleaning knives without a dishwasher?

You can use other safe and proper methods to wash knives without affecting their luster or sharpness.

The following cleaning techniques are effective and safe for cleaning knives:

1. Knives, especially those made with stainless steel, should be hand-washed in soapy water or just warm water.

2. It would help if you cleaned knives crafted of carbon steel with a clean cloth after each use. If running water is used to wash them, it should not be soaked in water to prevent corrosion, should be cleaned with a dry cloth immediately, and do not use soaps to clean knives made with carbon steel.

3. Soak a clean cloth in white vinegar at room temperature or slightly heated and wipe the blade with it, then clean with a dry cloth.

4. Use the flesh of potatoes on the knife’s blades, rinse with water, and air-dry or dry with a clean, dry cloth depending on the material used for making the knife.

5. Soak a clean cloth in turpentine at room temperature, wipe the blade, and dry with a clean cloth. Turpentine is especially useful to remove rust from knives.


A dishwasher is a useful kitchen machine that is used to wash a lot of kitchen utensils. However, it is not ideal for washing knives.

Washing knives in dishwashers can cause them to become dull in luster and sharpness. These can develop due to dishwashing detergent, frequent washing in a dishwasher, washing rusted kitchen utensils together with knives, and leaving the knives/dishes in the dishwasher for too long.

To prevent knives from becoming dull, they can be washed with hands using a mild soap, wiped clean with a clean, dry cloth after use, or wiped clean with a clean cloth soaked in vinegar or turpentine oil. You can also use the flesh of potatoes to clean knives.

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