What Cannot be Cleaned in Dishwasher? Must Know

Some items that cannot be cleaned in dishwasher are cast iron, wooden utensils, crystal, and sharp knives. These items can be damaged by the high heat, harsh detergents, or water pressure of the dishwasher. To keep them in good condition, they should be hand-washed instead. In this article, we will explain why these items are not dishwasher-safe and how to properly clean them by hand.

Cast Iron

Cast iron cookware is prized for its durability and ability to retain heat and create a nonstick surface. However, cast iron should never go in the dishwasher, as it can ruin its seasoning and cause it to rust. Seasoning is the layer of oil that is baked into the surface of cast iron, which protects it from rust and makes it nonstick. Dishwasher detergents can strip away this layer and expose the metal to water and air, which can lead to rusting.

To clean cast iron cookware, you should use plain water and a nonabrasive sponge or brush. Do not use soap, as it can also remove the seasoning. If there are stuck-on food bits, you can use coarse salt or baking soda as a gentle abrasive. Rinse the cookware well and dry it thoroughly with a towel. Then, apply a thin layer of vegetable oil or shortening to the surface and heat it over low heat for a few minutes. This will help restore the seasoning and prevent rusting. Store the cast iron cookware in a dry place.

See also  Is 1, 3, 4 or 5 colder on a fridge? Exactly what to Expect

Wooden Utensils

Wooden utensils, such as spoons, spatulas, cutting boards, and salad bowls, can also be damaged by the dishwasher. The high heat and moisture can cause the wood to warp, crack, or lose its finish. The wood can also absorb the dishwasher detergent, which can affect its taste and smell. Additionally, wooden utensils can harbor bacteria and mold if they are not dried properly.

To clean wooden utensils, you should use warm water and a mild dish soap. Do not soak them for too long, as this can cause the wood to swell and distort. If you need to disinfect them, you can use a solution of vinegar and water or bleach and water. Rinse the utensils well and dry them with a cloth. You can also rub some mineral oil or beeswax on the wood to condition it and prevent it from drying out. Store the wooden utensils in a cool and dry place.


Crystal is a type of glass that contains lead or other metals, which gives it a sparkling appearance and a high refractive index. Crystal is often used for fine stemware, vases, and decorative items. However, crystal is not dishwasher-safe, as it can chip, crack, or lose its shine. The dishwasher detergent can etch the surface of the crystal, making it cloudy and dull. The high temperature and water pressure can also cause the crystal to crack or break.

To clean crystal, you should use warm water and a gentle dish soap. You can also add some vinegar or lemon juice to the water to enhance the shine of the crystal. Use a soft cloth or sponge to wash the crystal, and avoid rubbing or scratching it. Rinse the crystal well and dry it with a lint-free cloth. You can also polish the crystal with a microfiber cloth or a paper towel. Store the crystal in a safe place, away from direct sunlight and heat.

See also  Are Electric Drywall Sanders Any Good?

Sharp Knives

Sharp knives, such as chef’s knives, paring knives, and steak knives, should also be kept out of the dishwasher. The dishwasher can dull the knife blades, as they can rub against other utensils or the dishwasher rack. The dishwasher detergent can also corrode the metal and cause rusting. Moreover, sharp knives can pose a safety hazard when loading and unloading the dishwasher, especially if you have children or pets.

To clean sharp knives, you should use warm water and a mild dish soap. You can also use a dish brush or a sponge to gently scrub the blades, but be careful not to cut yourself. Rinse the knives well and dry them with a towel. You can also hone the knives with a sharpening steel or a whetstone to maintain their edge. Store the knives in a knife block, a drawer, or a magnetic strip, away from other utensils.


Dishwashers are convenient and efficient appliances, but they are not suitable for every item in your kitchen. Some items that cannot be cleaned in dishwasher are cast iron, wooden utensils, crystal, and sharp knives. These items can be damaged by the dishwasher and should be hand-washed instead. By following the proper cleaning methods, you can preserve the quality and functionality of these items and enjoy them for a long time.