Wooden Spoons, Bowls and Cutting Boards
The harshness of dishwasher detergents can strip the natural oils that keep wooden utensils and cutting boards from drying out. When those oils are stripped, the wood will begin to crack.
The edges can nick the protective coating on racks and baskets causing rust to form, and those sharp edges are dangerous when unloading the dishwasher especially when kids are helping.
Harsh dishwasher detergent can dull edges and cause wooden handles to loosen and split. It’s best to hand wash all types of kitchen knives.
Graters and Sieves
Any kitchen tool with sharp edges should not be placed in the dishwasher. Graters and sieves can nick the plastic coating on the racks and rust will begin to form.
Cast Iron Cookware
Cast iron skillets and pans have been around for centuries and they can last nearly forever if they are cared for properly. To keep cast iron from rusting and food from sticking, it must be seasoned with oil. The oil penetrates the iron and leaves a near perfect cooking surface.
When the cast iron is placed in the dishwasher, the harsh detergent and excessive water strips away the oil and leaves the cast iron unusable. The seasoning process must be completely started over.
Aluminum Pans and Cookware
If the aluminum has not been anodized, the harsh detergent can cause pitting and corrosion. You may also see white spots on the surface from the alkalinity of the dishwasher detergent. Even if the pan is labeled as “dishwasher safe,” it’s better to hand wash.
Copper Pans and Mugs
The harsh chemicals in dishwasher detergent will immediately dull the finish and can be corrosive and cause the copper to pit.
Pitting is not going to be removed even with the best copper cleaner and elbow grease.
Pressure Cooker Lids
The lid contains the valves that control how well the cooker works. The action of a dishwasher can force small particles of food into the valves and vents and cause the cooker to malfunction (explode). The harsh chemicals can also damage the rubber or silicone seals of the lid.
While many nonstick pans are labeled as dishwasher safe, the harsh detergents and excessively high drying temperatures can take a toll on the nonstick coating. If you choose to wash your pans in the dishwasher, skip the drying cycle and allow them to air dry.
At the first sign of damage to the surface, it’s time for a new pan. When the nonstick surface is scratched, chipped or flaking, it can release dangerous toxins into the food.
Acrylic or Melamine Dishes
Lightweight, non-breakable acrylic or melamine dishware is very popular due to the bright colors and patterns. Unfortunately, the high water and drying temperatures and harsh dishwasher detergents can ruin the dishes. After several washings, especially for cheaper sets, there can be hairline cracks and loss of color and design.
If you love them and want them to last, hand wash.
Insulated Glasses, Tumblers and Thermal Containers
Plastic and metal insulated cups, tumblers and containers are great for keeping hot things hot and cold things cold. Most are constructed with two layers of material with an airspace between the two. It’s that airspace that provides the insulation.
While some containers are labeled as dishwasher safe, many are not. It is best to hand wash both plastic and metal insulated containers.
Printed or Hand Painted Glassware
The techniques for commercial printing on glassware have improved but they are not always infallible in the dishwasher. That harsh detergent and the force of the water spray can remove the paint in just one or two washes.
Thin Plastic Containers
If you save every butter tub and deli container to use for storage, be prepared to loose a few if you place them in the dishwasher. The high heat can cause them to melt or warp.
When you place them in the dishwasher, use the top rack only and skip the high heat drying cycle. Remove from the dishwasher to air dry.
Containers With Paper Labels
Along with your deli containers, you may also save glass food jars for storage. There’s no problem with placing the jars in the dishwasher, IF you remove the paper labels first. If you don’t, the paper and adhesive may come off and clog the dishwasher drain and food disposal system.
Gold Flatware and Metaliic Trimmed China
While sterling silver flatware travels through a dishwasher well, gold-colored flatware will dull and discolor in the dishwasher due to the harsh detergent.
Porcelain and fine china are dishwasher safe unless they have metallic trim or images. The harsh detergent and the strong water action of the jets can cause the metallic work to flake away. With any delicate china, take care when loading so that pieces don’t knock together and cause chipping.
Vintage China, Delicate Crystal and Repaired Items
For any glass or china heirlooms, skip the dishwasher and carefully hand wash. This is especially important for any item that has been repaired. The high heat and harsh detergents will cause the adhesives used to weaken and you may lose any small pieces.
Delicate crystal should be hand washed to prevent chipping. If you decide to use the dishwasher, use the top rack and place the glasses between the tines, not over them, to help avoid breakage. Remember, some lead crystal will become cloudy and…
Sterling Silver Knives
Sterling silver flatware goes through a dishwasher just as well as stainless steel, with one exception: Many sterling silver knives have a hollow handle and the heat of the dishwasher can cause the glue that holds the blade to the handle to melt and separate. This happens whether the blade is sterling or stainless steel. Hand wash instead.
Milk glass dishware, especially vintage milk glass, can turn yellow after several washings in the dishwasher thanks to the high heat and harsh detergent. Hand wash the pieces to keep them looking their best.