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The best way to load a dishwasher, according to science

Electrolux EI@4ID50QS0 dishwasher both racks
A few months ago, a semi-frustrated dad posted a YouTube video that featured him giving tongue-in-cheek instructions to his teens on how to load a dishwasher. It turns out most of us could use a similar video, as we have been performing this household chore all wrong.

It’s more about what’s on the dishes than whether they’re bowls or plates, according to a new study in Chemical Engineering Journal. University of Birmingham’s Dr. Raul Pérez-Mohedano conducted the research and recommends arranging the dishes in a circle, following the dishwasher’s rotating arms. These will be your filthiest dishes and encrusted with carbohydrates, like spaghetti. Meanwhile, dishes with protein stains, like from eggs, go around the edges of the dishwasher.

The researchers came to these conclusions after testing with a technique called Positron Emission Particle Tracking. The carb-stained plates get the benefit of being in the direct line of the appliance’s jets, and the protein-stained plates soak a little longer in the detergent, helping break up the gunk.

“The distribution of water inside a commercial dishwasher is very chaotic,” Dr. Pérez-Mohedano tells the Daily Mail. The jets hit very limited areas, and the rest of the water cascades back down, resulting in the majority of the water coverage.

“Current commercial dishwashers also show a problem of symmetry — while the ejection of water is produced in a circular movement, the distribution of the crockery follows a rectangular pattern,” says Dr. Pérez-Mohedano. “This automatically produces areas where the impact of water is going to occur for longer.

Depending of the soil type to remove, the best procedure to follow varies. For example, cleaning of protein-based soils, such as egg yolk, requires of an initial swelling/hydration stage, which is typically driven by high alkaline conditions at the beginning of the wash cycle… Other types of soils based on carbohydrates, like tomato paste, require less chemistry and more mechanical action.” Less chemistry and more mechanical action would make a great album title.

Naturally, cramming too many dishes in the machine impedes the jets and nothing gets quite as clean.

The researchers worked with engineers at Whirlpool and Proctor and Gamble on the study, so we’ll see if future dishwashers reflect these findings. Both Electrolux and Samsung have dishwashers with unique takes on the spray system, so we’re guessing manufacturers are well aware of the problem.

We really wish the study had said something about whether it’s better to load utensils handles up or down, though.

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