15. Disposable Aluminum
Disposable aluminum trays and containers can leave dark marks or react with the dishwasher environment. Some manufacturers specifically recommend keeping them out of the machine.
16. Tin Items
Tin can rust when exposed to the conditions inside a dishwasher, so hand washing is a better choice.
17. Decorative Glassware
Glasses with delicate decorations, painted details, or special finishes may lose their appearance after repeated dishwasher cycles.
18. Items With Unknown Care Instructions
This might be the most important one.
If you’re unsure whether something is dishwasher-safe, don’t assume that it is. Dishwasher-safe labeling isn’t completely standardized, and manufacturers can have different recommendations for similar-looking products.
The Simple Rule to Remember
Your dishwasher is excellent for everyday dishes, glasses, and many stainless-steel utensils. But materials such as wood, cast iron, delicate crystal, certain plastics, copper, and nonstick cookware often need extra care.
