When you load your dishwasher with plates, cups, and silverware, you obviously want everything to come out spic-and-span. You also want your dishware to come out dry enough to put away, eat from, or store food in. But have you ever noticed that your plastic cups and bowls probably come out covered with beads of water?

I only noticed after my daughter was born and I had loads of sippy cups and bright pink bowls in the dishwasher. It was happening so often, that I started to wonder if my dishwasher was working correctly, and if the beads of water indicated that the dishes weren’t clean.

It took awhile, but I’ve learned that this is a common phenomenon that happens when you put plastic in your dishwasher. Here’s why it happens.

The Scientific Explanation

First of all, rest assured that you are not alone in having wet plasticware at the end of every dishwashing cycle, and it’s not your stainless-steel lined appliance, either. The unwelcome moisture on your plastic dishes are a result of a couple scientific principles at work.

Conductivity: The inside of a dishwasher gets extremely hot, typically between 130° and 170°F. Metal, glass, and plastic have different capabilities to conduct and absorb heat, which ultimately has an impact on how quickly certain items dry. Plastic items are typically lighter and thinner, thus absorb less heat and the water is unable to efficiently evaporate.

Evaporation: Those extremely hot temperatures within the dishwasher not only kills germs and get your dishes sparkly clean, they also cause the water to evaporate. Because glass and metal items have substantial mass and retain more heat, the water on those dishes dry easily. However, because plastic is less dense, it doesn’t lock in the same amount of heat. As a result, plastic dishes are unable to evaporate water droplets as quickly, resulting in damp bowls and wet sippy cups when the drying cycle comes to an end.

Functionality of Machine

If you’re like me, you may be worried that your dishwasher is functioning incorrectly. Don’t fret. Your dishwasher is likely preforming just fine, even if your plastic dishes are wet at the end of the cycle. And this applies to all types of dishwashers, including 18-inch and portable versions.

It’s the other items that you need to keep an eye on. If your ceramic dishes, silverware or pots/pans are coming out wet, then you may have a problem with the heating element within the appliance. If this is the case, it may be time to put in a call for somebody to come take a look at it or just buy a new one.

Other Potential Glitches

In order to obtain the cleanest, driest, most spot-free dishes, avoid these kitchen-cleanup glitches:

Overzealous Pre-Washing: Are you rinsing your dinner dishes so thoroughly that they seem clean enough to eat off of? If your answer is yes, it’s time to reign in your domestic zeal, because today’s smart dishwashers will sense that there’s not enough grime to go through a full cycle, which can lead to a reduction of heat, shorter washes, and dishes that are not optimally cleaned. It’s advisable to simply scrape the plates, and leave the heavy scouring for the appliance.

Failure to Use Rinse Aid: You can promote drier dishes if you use rinse aids. This is because these products curtail water droplet formation, which ultimately helps the dishes dry faster.

Using Wrong Type of Detergent: If you’re using the wrong type of detergent in your dishwasher — such as the concentrated dish soap — you may notice that your dishes aren’t as pristine as they could be. Make sure you know the differences between dish soap and dishwashing detergent, as the two are commonly mistaken for each other.

Opting for Quick Wash Cycles: Your dishes will be cleaner and drier if you use full cycles on your machine, so skip the short cycles if you want better end-results.

Placing Plastic on Lower Racks: To reduce heat exposure, make sure you put all plasticware on the top rack. When larger plasticized containers don’t fit up top, you’ll have to wash them by hand or wait for another load.

Dirty Dishwasher: To keep this appliance in top form, you should routinely clean its interior. Because of its constant contact with grease, soap scum, and food bits, bacteria can grow in its corners and crevices. Your machine can also develop an unpleasant odor; so once a month, wipe out the tub and run a dish-free cycle with a cup of white vinegar. This should keep your dishwasher looking and smelling brand-new for many cycles to come.

Know Your Plastic

Not all plastic dishes and containers are the same, so be sure the ones you’re putting through wash cycles can handle the heat. Some plasticware is meant to be reused, is BPA-free, and is usually marked to specify this, while other containers are inappropriate for reuse.

Polypropylene #5: Some foods, such as yogurts and peanut butters, are routinely packaged in polypropylene #5 plastic. The good news is that this material is not toxic, but the bad news is anything made out of this type of plastic is likely too flimsy to be exposed to high temperatures and detergents, and will likely melt in the dishwasher.

BPA: Beware of Bisphenol A. Food containers and water bottles have been made from BPA plastic for decades. This chemical can be detrimental to health, especially if it’s exposed to high heat, so should be hand-washed if used at all.

Plastic is a remarkable product when it comes to lightweight and versatile kitchenware. Cups can be easily managed by young children, plates and bowls won’t shatter if they’re dropped, and these items come in vibrant colors and patterns. So, if you’ve found yourself wondering why your plastic dishware is still wet at the end of the drying cycle, don’t worry, you aren’t doing anything wrong.