Why Plastic Containers Never Dry in the Dishwasher

When your dishwasher has just finished a wash and dry cycle, you may notice that something strange always seems to happen: your plastic cups, utensils and cutlery never seem to have dried off. Everything else – including the glassware – seems dry, but never the plastic stuff. This leaves you having to do some extra work drying items off that you’d rather your dishwasher had taken care of instead.

It’s easy to look at this as a failing of your dishwasher. You may want to call a repair company (like our team at Repair Aid) to come and have a look at your dishwasher for a fault; or perhaps you’re looking to buy a new one instead. Well, in actual fact, it’s not your dishwashers fault at all… dishwashers just aren’t good at cleaning plastic containers. And it’s not because your dishwasher is being stubborn or picky either – the answer is one that can be explained by a little bit of science.

According to some experimentation and deduction from the boffins at NC State University, it’s to do with plastic absorbing a different amount of heat than other materials. That’s not to say plastic is unique in that regard – all materials have different thresholds – but it’s to do with the density of materials.

Plastic actually can retain heat more than the likes of glass or ceramics at an equal weight; however, because a higher quantity of ceramic and glass is used in such dishes or glasses than plastic equivalents (such as bowls and cups/glasses), then more heat is absorbed than the plastic versions.

As such, this leads to more water being left over on the plastic dishes than the others. So what has that got to do with your dishes getting properly dry?

Well, if some items in the dishwasher aren’t getting as warm as others, then they’re not going to dry off as well. It’s often why certain clothes dry faster than other clothes if you hang them out to dry too.

To spell it out, there are two primary reasons why plastic will always struggle to dry in the dishwasher.

Number one: as the non-plastic items retain more heat, then this will cause the water to evaporate faster than on plastic items (which will be much cooler).

Number two: the plastic item’s surface temperature will cause the water to condense on the surface instead – and thus the water is retained on the plastic.

Great, so what can you do about that?

Well, we’re sorry to say that there’s virtually nothing you can do to ‘cheat’ or ‘hack’ scientific laws here. If you want your dishes dry after they’ve been cleaned, then you’re going to have to hand-dry the dishes. However, there’s a way that you can ensure that your dishes will all be clean: do them in advance.

While many can tend to do their dishes just an hour or two before they need them, why not do them well in advance? If you leave your plastic dishes, containers and cutlery in the dishwasher for longer, then they will naturally dry without you needing to intervene. So with a bit of more careful planning around your dishwasher habits, you might be able to avoid this problem.

The last solution we can suggest is to try to better space out your dishes and utensils on the dishwasher rack. This will allow heat to be proportionally dished out as more space and exposure to hotter air will allow the plastic to dry more quickly. As well as this, you could try introducing some sort of rinse aid product. However, you’ll want to look at your user guide to find out how much is best to use in your machine.

So while we may not have solved your quandary, we hope that you’ve come up with the alternative answer: get someone else to sort out the dishes!

An alternate solution

But we do have one more possibility for you. As home appliances continue to get more technologically advanced, we’re starting to see new tech being employed to solve older problems: including the plastic dish problem.

There are some newer machines that include a plastic dish setting. An example of this include Bosch’s PerfectDry system. So if you’re on the lookout for a new machine and this problem really annoys you, it’s worth knowing about this function before you buy.