To many people in the developed world the dishwasher is still a relatively new invention. My parents, for example, did not get one until the early 1990s. So, it may come as a surprise to learn that dishwashers first appeared in a very basic, hand powered form, in 1850.
Developed in the USA the early dishwasher was little more than a mechanical means to move dishes under a spray of water. Famously Josephine Cochran came up with a more complex design in 1887, although this too was hand-powered.
In fact it wasn’t until 1924 that a front-loading model was invented. This time, unlike the earlier incarnations, it was a UK development that included permanent plumbing, a familiar looking wire rack to hold the dishes and the now ubiquitous rotating water spray arm. By 1940 this design had been enhanced to include drying elements.
Despite these early breakthroughs, mechanical dishwashers did not initially become commonplace and, for a while, were portable appliances that could be moved to a suitable place for use before being stored away when not required.
The introduction of fixed kitchen work tops changed all that. At that stage the dishwasher became a more permanent fixture, generally located beneath a work surface, near to the sink.
bosch dishwasher sms46ki03i As kitchen design took off in the 1970s so did the popularity of the dishwasher. And now a suggested 78 per cent of U.S. homes have one.
In recent times the general design of the dishwasher has changed very little. The interiors have certainly been improved though as has the operation of the spray arm, both in an effort to increase performance with a lot of consideration given to unusual shapes of crockery. In fact it is this change that has been most pronounced.
While spray arm operation has improved, the challenge of ensuring that particles of food are removed from oddly shaped items means that the standard of dishwasher performance is heavily dependent, even today, on the skill of the stacker.
Other than providing best practice guidelines, advice and tips and clear instructions, there really is very little that a dishwasher manufacturer can do to improve performance if the pots, pans, knives, forks, plates and spoons are thrown in at all angles.
For optimum performance dishwasher items must always be stacked in such a way that will allow free movement of the water around the cavity. And even present day dishwashers have not solved the problem of water retention in items that have been stacked upright instead of the universally approved position of upside down.
Improvements to spray arm power has meant that the cleaning ability is certainly increasing. For it to be effective, however, only items that are stacked correctly will benefit.
At the same time the power of the water jet must also be carefully regulated in order to preserve more delicate items of crockery. As a result, it is commercial dishwashers only that have been able to successfully increase power levels in order to wash more uniformly sized or robust items.
Therefore, when it comes to dishwasher design, it is more likely that kitchen or tableware fashion – and not engineering or ergonomic advance – is the catalyst for change. A recent trend for larger dinner plates, for example, has prompted some manufacturers to offer adjustable basket heights. Racking that can adapt to different sizes of crockery has also been included.
The dishwasher is still evolving though.
One of the few remaining features of the early dishwasher, the cutlery basket, is now becoming a cutlery tray. This subtle difference means that a variety of different sizes and shapes of cutlery can be stacked safely and conveniently while simultaneously freeing up basket space for additional crockery items.
Other improvements have been made to dishwasher design in order to reduce environmental impact. The most notable of these is the use of just the cold water supply instead of both hot and cold. This method, by which the dishwasher heats the water itself, is more economical when it comes to getting water to the desired temperature than the domestic hot water supply.