Oh, the promise of a plastic cup labeled “top rack dishwasher safe” is fulfilled! Carefree kitchens with drinking utensils that are not only shatterproof, but dishwasher safe too. No more piles of plastic items waiting to be hand washed. An escape from boredom … relief from monotony!
Indeed.
Dishwasher-safe, clear plastic beverage containers are certainly a reality for some. But anyone with a dishwasher less than ten years old may have a different opinion. Your “dishwasher safe top rack” glasses often come out of the top rack creaking, flaky, or cloudy, sometimes after just a few wash cycles. What gives?
For those who are quick to point the finger at plastic cup makers for mislabeling their products, brace yourselves. It’s not the plastic cups that are faulty, it’s that dishwashers have changed a lot in the last decade, primarily due to the EPA’s Energy Star guidelines for energy efficient appliances.
Most dishwashers made before 1994 draw hot water directly from a home’s water heater, which is usually set at about 140 degrees F. Although too hot for most household needs, 140 degrees is the optimal cleaning temperature recommended by most dishwasher detergents, and will not harm most “top rack dishwasher safe” plastic cups. .
Newer Energy Star-rated dishwashers feature built-in water heaters that further heat the wash and rinse cycle of the water up to 30 degrees. Since the incoming water no longer needs to be as hot, domestic water heaters can be turned down to 115 or 120 degrees to save energy, which is fine for other household uses.
Unfortunately, home water heater settings are often overlooked when a new dishwasher is installed. And while a 30-degree rise doesn’t sound like much, it may be enough to break the heat tolerance of many dishwasher-safe plastics.
But there are ways to enjoy the benefits of the newer dishwashers without giving up the convenience of plastic dinnerware.
Those with an Energy Star rated dishwasher should first consult their owner’s manual for the wash setting water temperatures. If possible, wash plastic dishes in an unheated place so that incoming hot water does not overheat. If there is no no-heat option, check your home’s water heater. If it is set around 140 degrees, lower it to 120 degrees, so that the final temperature of the water in the dishwasher does not exceed 150 degrees.
For drying, the air dry setting is generally better for extending the life of plastic dinnerware, as heat drying temperatures can be excessive for many plastics.
Lastly, not all plastics are created equal – some plastics work much better in all types of dishwashers than others.
For long-lasting good looks, drinkware and dishes made of strong plastics such as melamine, SAN, polypropylene, or polycarbonate are better options than items labeled “top rack,” which are generally less durable acrylic or polystyrene. Dishware made from these better quality plastics is often found in busy restaurants, as it can withstand repeated washings in commercial dishwashers up to 155 degrees.
Best of all, most restaurant-grade plastic dinnerware is “dishwasher safe on any rack.” Now, that is a convenience to sing.