"Dishwasher safe" but "top rack only" is a common labeling found on some plastic kitchen items, especially those made from certain types of plastics that may not withstand the high heat and aggressive water jets typically present in the bottom rack of a dishwasher. Let's break down what this labeling means:
"Dishwasher safe": When an item is labeled as "dishwasher safe," it means that the material used to manufacture the item is generally safe to be washed in a dishwasher without causing significant damage or degradation. Dishwasher safe items can withstand the conditions inside a dishwasher, such as exposure to water, detergent, and high temperatures, without breaking, warping, or releasing harmful substances.
"Top rack only": The label "top rack only" indicates that the plastic item is safe to be placed on the top rack of the dishwasher but not the bottom rack. The top rack of a dishwasher is generally exposed to lower temperatures and gentler water jets compared to the bottom rack, which makes it a safer place for more delicate or heat-sensitive items.
The reason some plastic items are recommended for the top rack only is that the bottom rack is closer to the dishwasher's heating element, which can subject the items to higher temperatures. Certain types of plastics may not be able to withstand these higher temperatures and may melt, warp, or release harmful chemicals when exposed to the intense heat from the heating element.
If you place an item labeled as "top rack only" on the bottom rack, there is a risk that it may not hold up well during the dishwasher's cleaning cycle. The plastic could deform, lose its shape, or leach chemicals into your dishes, rendering the item unusable and potentially contaminating your other kitchenware.
To ensure the longevity of your plastic kitchen items and prevent damage, it's best to follow the manufacturer's guidelines and only place items labeled as "top rack only" on the top rack of your dishwasher. If the item is too large or won't fit on the top rack, it's safer to wash it by hand using mild soap and water to preserve its integrity and functionality.