10 Things You Must Never Wash in Dishwasher

Dishwashers help save time and effort. It allows us to enjoy eating with friends and family and not worry about the after-cleaning. 

While it makes washing most dishes and utensils a breeze, certain items should not be cleaned in a dishwasher. 

Putting these delicate or sensitive items in the dishwasher can damage them, reduce their functionality, or even become hazardous.

Let me guide you to ten things you must never wash in a dishwasher and why. I will also share guidelines on how to wash them using alternative methods.

10 Things You Must Never Wash in Dishwasher

While I will cover the details of each item in details, here is a list of things you should never wash in a dishwasher: 

Item Not to Wash in Dishwasher Reason
Cast Iron PansRemoves seasoning and causes rust
Wooden Utensils and Cutting BoardsCauses warping and splintering
Nonstick CookwareDegrades nonstick coating
Crystal and Hand-Blown GlasswareCauses chipping, cracking, and clouding
Aluminum CookwareDiscolors, dents, and warps
KnivesCauses blades to become dull and rust
Copper or Brass ItemsDishwashers can damage finish and dull color
Gold-Plated dishware or UtensilsWears off the gold plating
Insulated Travel MugsDamages vacuum seal
Plastic Items Not Marked “Dishwasher-Safe”Can warp, melt, or release chemicals

Now, if you’re interested in knowing the details of each item, let’s do that here.

Cast Iron Pans

Cast iron pan is a staple in many kitchens due to its excellent heat retention and ‘even cooking’ property. 

However, for proper care of your cast iron cookware, never wash them in the dishwasher.

Dishwashers use harsh detergents and high water pressure that can strip away the seasoning from your cast iron pan. 

Seasoning is the process of coating the pan with oil and heating it to create a natural non-stick surface. 

The seasoning protects your pan from rust and makes it easier to cook. 

Washing your cast iron pan in the dishwasher will remove this protective layer, leaving your pan prone to rust and making it less effective for cooking.

Moreover, the high heat and excessive moisture in the dishwasher can also cause rust to develop on your cast iron pan, further damaging your pan’s surface and overall usability.

 Rust can also transfer onto your food and ruin the taste.

How to Clean Them Instead 

So, how should you clean your cast iron pans instead? Follow these simple steps:

  • Allow your pan to cool down after cooking to a comfortable temperature to handle.
  • Rinse the pan with hot water to remove any food particles, using a long-handled scrub brush if necessary.
  • If stubborn residue remains, add a few drops of dish soap and gently scrub with a non-abrasive sponge or brush.
  • Rinse the pan thoroughly with hot water to remove any soap residue.
  • Dry the pan immediately with a clean towel or place it over low heat on the stovetop to evaporate any remaining water.

To maintain your cast iron’s seasoning, lightly coat the surface with a small amount of oil and rub it in using a clean cloth or paper towel.

Wooden Utensils and Cutting Boards

Wooden cutting boards, wooden spoons, salad bowls, and other wooden items are great additions to your kitchen, thanks to their durability and ability to resist bacteria growth. 

However, these items can be damaged by putting them in the dishwasher. 

The high heat and moisture in the dishwasher can cause warping, splintering, and eventually breaking of these wooden pieces.

How to Clean Them Instead 

To maintain the quality and prolong the life of your wooden kitchen tools, you should wash them by hand. 

First, use warm, soapy water to clean the wooden utensils and cutting boards. Be sure to remove any food particles and stains. Rinse them well with clean water to eliminate soap residue.

When drying your wooden items, it is essential to remove excess moisture as quickly as possible to prevent warping and cracking. 

Use a clean kitchen towel or paper towel to pat the items dry immediately after washing. 

Additionally, you can air-dry them by placing them on a drying rack or towel, ensuring that air can circulate on all surfaces.

Regular maintenance of your wooden cutting boards and utensils includes applying mineral oil. 

After your items are clean and completely dry, coat them with a thin, even layer of mineral oil using a clean cloth or paper towel. 

This oil will keep the wood moisturized, prevent cracks, and prolong its life. Allow the oil to soak into the wood for a few hours or overnight before using your items again.

Also read: Can You Put Wooden Spoons in Dishwasher?

Nonstick Cookware

Nonstick cookware, such as a nonstick pan is incredibly convenient when it comes to cooking.

Most nonstick cookware is not dishwasher safe, and using high heat and harsh detergents can lead to the degradation of the nonstick coating.

The reason behind this is that the high heat and water pressure in the dishwasher can cause the nonstick coating to lose its effectiveness over time. 

This makes it less efficient at preventing food from sticking. 

Moreover, harsh dishwasher detergents can erode the nonstick surface, further reducing the lifespan of your cookware.

How to Clean Them Instead 

To maintain the integrity of your nonstick cookware, it’s best to wash it by hand. Use warm, soapy water and a soft sponge or cloth to gently clean the surface. 

Avoid using abrasive scouring pads or steel wool, as these can scratch and damage the nonstick coating. 

Rinse your pans thoroughly and make sure to dry them completely before storing them away. This will help to prevent any moisture from causing damage.

Crystal and Hand-Blown Glassware

When it comes to delicate items like crystal and hand-blown glassware, the dishwasher is not your friend. 

These fragile pieces require special care to maintain their beauty and integrity. 

Placing them in the dishwasher can cause damage, such as chipping, cracking, or clouding, making them lose their shine and possibly even their usefulness.

One reason for their incompatibility with dishwashers is that they are typically more delicate than standard glassware or stemware. 

The high water pressure and heat generated in the dishwasher can cause the crystal and glass to develop fine scratches, ultimately making it appear cloudy or etched. 

In some cases, especially with hand-painted glass or milk glass, the dishwasher can even wash away the decorations or colors, ruining their unique appearance.

How to Clean Them Instead 

The best way to clean your precious crystal and hand-blown glassware is by hand-washing them. 

Fill a sink or basin with warm, soapy water and gently wash each piece, paying special attention to any intricate designs or patterns. 

Avoid using abrasive sponges or brushes that could scratch the surface of your delicate glassware.

After washing them, carefully rinse each piece under warm running water to remove any soap residue. 

Lastly, dry your glassware with a soft, lint-free cloth to prevent water spots or damage from air drying.

Aluminum Cookware

Aluminum cookware, including pots and pans, should not be washed in the dishwasher. 

The high heat and harsh detergents used in the dishwasher can damage the aluminum, causing it to become discolored, dented, or warped. 

The exposure to high heat can also strip off the non-stick coating and reactive surface from your cookware, reducing its performance and lifespan.

How to Clean Them Instead 

When you need to clean your aluminum cookware, it’s a better idea to wash them by hand. 

To do so, fill your sink with warm, soapy water and gently scrub the cookware with a non-abrasive sponge or soft dishcloth. 

Avoid using steel wool, scouring pads, or abrasive cleaners, as these can scratch the aluminum surface and cause further damage.

Be sure to rinse the cookware thoroughly with clean water to remove any soap residue. Finally, dry your aluminum pots and pans completely with a soft dish towel to prevent water spots and oxidation.


Knives, especially sharp kitchen knives, should never be washed in a dishwasher. There are several reasons why putting knives in the dishwasher is not a good idea. 

Firstly, the heat, humidity, and aggressive detergents used in the dishwasher can cause the blades to become dull, blunt, warped, and more susceptible to rust. 

Additionally, knives can damage the plastic coating on dishwasher shelves, exposing the metal underneath to rust.

How to Clean Them Instead

Instead of using a dishwasher, it’s best to hand wash your knives. Follow these simple steps to ensure your knives remain in excellent condition:

  • Gently clean the blade and handle with warm water and mild detergent. Be careful not to scrub too hard, as this may cause scratches on the blade.
  • Rinse the knife thoroughly under warm water to remove any soap residue.
  • Immediately dry your knife with a soft, clean towel. This is important because moisture left on the blade can lead to rust and discoloration.
  • Regularly sharpen your knives. By keeping your kitchen knives sharp, you’ll prevent them from becoming dull and dangerous to use. A dull knife is more likely to slip and cause an accident than a sharp one.

Copper or Brass Items

When it comes to washing your beautiful copper or brass items, it’s important to keep them out of the dishwasher.

Dishwashers can damage the finish and dull the color of these metals, including copper pots, brass utensils, and bronze decor. 

Copper and brass are known for their luster and shine, which can be easily tarnished in the dishwasher.

The powerful spray and harsh detergents of the dishwasher can cause discoloration and accelerate the formation of the patina.

While a patina can be desirable in some instances, it is likely not the look you want for your everyday kitchen items.

Not only do copper and brass items require special care, but gold leaf detailing found on some of these items can also be damaged in the dishwasher. 

Gold leaf is a delicate material prone to wearing off when exposed to the rigors of machine washing. To preserve the appearance of your gold leaf-adorned pieces, be sure to hand-wash them as well.

How to Clean Them Instead

When hand-washing your copper, brass, and gold leaf items, use gentle soap and warm water.

Opt for a soft sponge or cloth to gently scrub the surface. Avoid using steel wool or abrasive sponges, as they can scratch the surface. 

Rinse with warm water and carefully dry the items with a soft cloth to avoid water spots or streaks.

Gold-plated Dishware or Utensils

One of the items that you must avoid washing in the dishwasher is gold-plated dishware or utensils. 

Gold-plated flatware is delicate and prone to damage due to the abrasive nature of dishwasher detergents and the high temperatures in the dishwasher. 

These factors could cause the gold plating to wear off, leaving your beautiful flatware looking tarnished and less attractive.

How to Clean Them Instead

It is highly recommended that you hand-wash your gold-plated dishware and utensils. 

Hand-washing allows you to control the water temperature and the pressure applied to the items, thus preserving their beauty for a longer period. 

Use a soft sponge and a gentle dishwashing liquid that is formulated for delicate items. Avoid using harsh chemicals, scrub brushes, or steel wool that could damage the gold finish.

Remember to immediately dry your gold-plated dishware and utensils after washing to prevent water spots or mineral deposits from dulling the surface. 

Insulated Travel Mugs

Insulated travel mugs are a popular choice for keeping your beverages hot or cold for extended periods. 

These mugs usually have a vacuum seal between the inner and outer shell, which helps maintain the beverage’s temperature. 

It is important to avoid washing your insulated travel mugs in a dishwasher, as doing so can cause damage to both the mug and the dishwasher.

The heat and high-pressure water in the dishwasher can breach the vacuum seal, filling it with water and creating an annoying sloshing sound. 

Furthermore, this may hinder the mug’s ability to retain heat, ultimately defeating the purpose of an insulated travel mug.

Another reason to keep your insulated mugs out of the dishwasher is that harsh detergents used can wear away the outer coating, affecting the mug’s appearance and potentially causing leaks. 

Some travel mugs also have intricate designs or logos that may be ruined when exposed to the dishwasher’s cleaning process.

How to Clean Them Instead

To maintain the effectiveness, functionality, and aesthetics of your insulated travel mugs, it is best to hand-wash them. 

Simply use warm, soapy water and a soft sponge to gently scrub the inside and outside of the mug. Be sure to rinse thoroughly to remove any soap residue. 

A quick wipe inside with a soft cloth can help remove hard-to-reach areas such as the lid or the grooves around the rim.

Use a soft, lint-free cloth to gently pat them dry, ensuring that you remove all moisture from the surface before storing them away.

Plastic Items Not Marked ‘Dishwasher-Safe’

When it comes to washing plastic items in the dishwasher, it’s essential to pay attention to whether or not they are marked as ‘dishwasher-safe.’

If a plastic container, bowl, or cup doesn’t have this label, it’s best to err on the side of caution and wash it by hand.

Many plastics, especially thin plastic containers, can warp, melt, or even release harmful chemicals when exposed to the high heat and harsh detergents used in the dishwasher. 

These changes in the plastic’s integrity can make your items unusable and potentially unsafe, particularly if they come into contact with food.

To avoid damaging your plastic items, make it a habit to check them for the ‘dishwasher-safe’ label before putting them in the washer. 

How to Clean Them Instead

For those that aren’t dishwasher-safe, handwashing them with mild soap and warm water is the best alternative.

This method not only helps preserve the quality and longevity of your plastic items but also ensures your family’s safety by preventing the release of any harmful substances.

When you do have dishwasher-safe plastic items, it’s still a good idea to place them on the top rack of your dishwasher. 

This position ensures they’re away from the dishwasher’s heating element and can reduce the risk of any damage caused by extreme heat. 

Remember, always double-check your plastic items for the ‘dishwasher-safe’ label, and when in doubt, opt for handwashing to avoid any potential damage or health risks.

For more details, watch the video below:

Frequently Asked Questions

Here are some frequently asked questions: 

How Does a Dishwasher Affect Non-dishwasher Safe Plastics?

Non-dishwasher-safe plastics can get damaged or warped when exposed to the high heat and water pressure in a dishwasher. 

It’s important to check if a plastic item is dishwasher safe before putting it in the dishwasher, and if not, wash it by hand with warm water and mild detergent.

Is It Safe to Wash China With Silver Trim in a Dishwasher?

It’s not recommended to wash china with silver trim in a dishwasher. 

The high heat and harsh detergents used in a dishwasher can cause the silver trim to wear off or become discolored. 

Instead, gently hand-wash these pieces with warm water and a mild detergent, and dry them with a soft cloth.

Why Is It Not Recommended to Put Wooden Utensils in a Dishwasher?

Wooden utensils are prone to warping, cracking, and splitting when subjected to high heat and moisture in a dishwasher. 

It’s best to wash them by hand using warm water and a mild detergent, and then dry them immediately to prevent moisture absorption.

Can Crystal Glassware be Cleaned in a Dishwasher?

It’s not advised to clean crystal glassware in a dishwasher. The high heat and water pressure can lead to chipping, cracking, or etching on the delicate surface of the crystal.

Instead, hand-wash crystal glassware gently using warm water and a mild detergent, then dry it with a soft, lint-free cloth to maintain its shine and clarity.

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I’m Jueria and I am a regular contributor on cookeryspace.com. In my articles, I share time-saving techniques, appliance wizardry, and health-friendly recipes to bring taste and wellness to your table. So raise a glass (or a spatula) with me, to good health and good food, made easy!