When something is labeled as "Not Dishwasher Safe," it means that the item is not safe to be placed in a dishwasher for cleaning. It's a warning from the manufacturer indicating that the dishwasher could potentially damage the item or reduce its lifespan.
Dishwashers use hot water and powerful jets to clean dishes, glasses, and utensils. However, some materials and items may not be able to withstand the heat, pressure, or aggressive detergents used in dishwashers. For example, delicate glassware, certain types of plastics, wooden utensils, or items with glued components might not be dishwasher safe.
To avoid damaging your items and ensure their longevity, it's essential to follow the manufacturer's instructions and care guidelines. If an item is labeled as "Not Dishwasher Safe," it's best to wash it by hand using gentle detergent and warm water or follow any other recommended cleaning methods provided by the manufacturer.