Dishwasher

A dishwasher is a machine that is used to clean dishware, cookware, and cutlery automatically. Unlike manual dishwashing, which relies heavily on physical scrubbing to remove soiling, the mechanical dishwasher cleans by spraying hot water, typically between , at the dishes, with lower temperatures of water used for delicate items. A mix of water and dishwasher detergent is pumped to one or more rotating sprayers, cleaning the dishes with the cleaning mixture. The mixture is recirculated to save water and energy. Often there is a pre-rinse, which may or may not include detergent, and the water is then drained. This is followed by the main wash with fresh water and detergent. Once the wash is finished, the water is drained; more hot water enters the tub by means of an electromechanical solenoid valve, and the rinse cycle(s) begin. After the rinse process finishes, the water is drained again and the dishes are dried using one of several drying methods. Typically a rinse-aid, a chemical to reduce the surface tension of the water, is used to reduce water spots from hard water or other reasons. In addition to domestic units, industrial dishwashers are available for use in commercial establishments such as hotels and restaurants, where many dishes must be cleaned. Washing is conducted with temperatures of and sanitation is achieved by either the use of a booster heater that will provide an "final rinse" temperature or through the use of a chemical sanitizer. The first mechanical dishwashing device was registered for a patent in 1850 in the United States by Joel Houghton. This device was made of wood and was cranked by hand while water sprayed onto the dishes. The device was both slow and unreliable. Another patent was granted to L.A. Alexander in 1865 that was similar to the first but featured a hand-cranked rack system. Neither device was practical or widely accepted. Some historians cite as an obstacle to adoption the historical attitude that valued women for the effort put into housework rather than the results—making household chores easier was perceived by some to reduce their value.