You Were Right; Packing the Dishwasher Really is a Science

Academic research determines how to get the best clean

Plastics in the top, plates on the bottom, knives pointing down and forks pointing up, platters lying flat and bowls upside down. Or is it the other way around?

Packing a dishwasher can lead to domestic disputes in the best of households, either the fine China isn’t cleaned properly or the pile of dessert bowls has fallen over. That said, is there a correct way of stacking your cutlery and crockery? Yes, there is, researchers have scientifically determined what that algorithm is.

Dr Raúl Pérez-Mohedano*, who takes the science of clean casserole dishes very seriously, led the academic study at the University of Birmingham’s chemical engineering department.

Researchers infused water with radioactive tracers to follow the movement of the water when the dishwasher was put inside a scanner. After running the dishwashers on their numerous cycles – stacked with dirty dinner ware – the scientists came to a conclusion. The most efficient pattern of packing the drawers is to place crockery in a circle around the cutlery basket to ensure they are hit by the water jets. Considering the square design of dishwashers, this is not ideal. It therefore comes down to what soiled the side plate in the first place. Most carbohydrate-based stains such as potato and tomato need the full force of the water jets to be cleaned, while protein-based foods such as dried egg yolk needs more contact with the chemical detergent.

The study showed that the areas towards the edges of the dishwasher basket on the bottom shelf, tend to be where water travels slower. It found that the lowest velocities for the water were close to the walls of the dishwasher at a height of between 5cm and 20cm. Pérez-Mohedano says most of the water coverage is caused by small waterfalls from other dishes. The area between 30cm and 60cm was sprayed with the fastest-moving water. This means that the area immediately above the rotating arms of the dishwasher and in the centre of the top shelf appear to be the best places to put dishes cemented with mashed potato that need the full force of the water.

“This is why WaterWall™ Technology sets Samsung’s dishwashers apart. The technology gets rid of the traditional rotating spray arm in favour of a full-width spray bar that moves front-to-back creating a wall of water. High pressure jets of water get right to the edges of the compartment promising pristine cleaning wherever and however one stacks the dishes in the machine,” says Mike van Lier, Director of Consumer Electronics at Samsung South Africa.

The WaterWall™ Technology is further enhanced by the ability to increase water pressure to one side of the lower tray. This is useful if you place particularly grimy bowls on one side and easier to clean plates on the other. In a similar way, the half-load programme can be optimised to work best in the upper half or lower half of the machine depending on how you have packed the dishwasher.

* http://www.sciencedirect.com/science/article/pii/S1385894714010870