Editing Dishwasher (section)

==Differences between dishwashers and hand washing==

===Dishwasher detergent===
{{Main|Dishwasher detergent}}

[[File:Detergent tablet.jpg|thumb|A detergent tablet]]
Dishwashers are designed to work using specially formulated [[dishwasher detergent]]. Over time, many regions have banned the use of [[phosphates in detergent]] and phosphorus-based compounds. They were previously used because they have properties that aid in effective cleaning. The concern was the increase in [[algal bloom]]s in waterways caused by increasing phosphate levels (see [[eutrophication]]).<ref name="Kogawa 2017">{{cite journal|last1=Kogawa|first1=Ana Carolina|last2=Cernic|first2=Beatriz Gamberini|last3=do Couto|first3=Leandro Giovanni Domingos|last4=Salgado|first4=Hérida Regina Nunes|title=Synthetic detergents: 100 years of history|journal=Saudi Pharmaceutical Journal|volume=25|issue=6|pages=934–938|date=February 2017|doi=10.1016/j.jsps.2017.02.006|pmid=28951681|pmc=5605839}}</ref> Seventeen US states have partial or full bans on the use of phosphates in dish detergent,<ref>{{cite web|url=https://www.washingtonpost.com/wp-dyn/content/article/2007/03/02/AR2007030201805.html |title=Md. Dish Soap Bill Might Help Clean Bay |work=Washingtonpost.com |date=2007-03-03 |access-date=2012-06-20}}</ref> and two US states ([[Maryland]] and [[New York (state)|New York]]) ban phosphates in commercial dishwashing. Detergent companies claimed it is not cost effective to make separate batches of detergent for the states with phosphate bans, and so most have voluntarily removed phosphates from all dishwasher detergents.<ref>{{cite web|url=http://www.geappliances.com/appliances/dishwashers/why-is-there-white-film-on-glassware-dishes-dishwasher-interior.htm |title=Phosphate Free Dishwasher Detergent Leaves Dishes Dirty |publisher=GE Appliances |access-date=2013-11-30}}</ref>

In addition, [[rinse aid]]s have contained [[nonylphenol]] and nonylphenol ethoxylates. These have been banned in the European Union by EU Directive 76/769/EEC.{{Cn|date=March 2025}}

In some regions, depending on water hardness, a dishwasher might function better with the use of a [[dishwasher salt]].{{Cn|date=March 2025}}

===Glassware===
Glassware washed by dishwashing machines can develop a white [[haze]] on the surface over time. This may be caused by any or all of the below processes, of which only the first is reversible:
; Deposition of minerals: Calcium carbonate ([[limescale]]) in hard water can deposit and build up on surfaces when water dries. The deposits can be dissolved by vinegar or another acid. Dishwashers often include [[ion exchange]] device to remove calcium and magnesium ions and replace them with sodium. The resultant sodium salts are water-soluble and don't tend to build up.{{Cn|date=March 2025}}
; Silicate filming, etching, and accelerated crack corrosion: This film starts as an iridescence or "oil-film" effect on glassware, and progresses into a "milky" or "cloudy" appearance (which is not a deposit) that cannot be polished off or removed like limescale. It is formed because the detergent is strongly alkaline (basic) and [[Sodium silicate#Properties|glass dissolves slowly in alkaline aqueous solution]]. It becomes less soluble in the presence of silicates in the water (added as anti-metal-corrosion agents in the dishwasher detergent). Since the cloudy appearance is due to nonuniform glass dissolution, it is (somewhat paradoxically) ''less'' marked if dissolution is higher, i.e. if a silicate-free detergent is used; also, in certain cases, the etching will primarily be seen in areas that have microscopic surface cracks as a result of the items' manufacturing.<ref>{{cite web |url=http://www.scienceblog.com/community/older/2003/F/20033788.html |title=Lehigh-Unilever study sheds light on mystery of cloudy wineglasses |publisher=Scienceblog.com |access-date=2012-06-20 |archive-date=2006-10-22 |archive-url=https://web.archive.org/web/20061022172645/http://www.scienceblog.com/community/older/2003/F/20033788.html |url-status=dead }}</ref><ref>{{cite journal |doi=10.1111/j.1151-2916.2003.tb03538.x |last1=Sharma |first1=Anju |last2=Jain |first2=Himanshu |last3=Carnali |first3=Joseph O. |last4=Lugo |first4=Guillermo Manuel |title=Influence of the Manufacturing Process on Corrosion Behavior of Soda-Lime-Silicate Glassware |journal=Journal of the American Ceramic Society |url=http://www3.interscience.wiley.com/journal/118861292/abstract?CRETRY=1&SRETRY=0|archive-url=https://archive.today/20121107001214/http://www3.interscience.wiley.com/journal/118861292/abstract?CRETRY=1&SRETRY=0|url-status=dead|archive-date=2012-11-07|access-date= 2010-06-09 |volume=86 |pages=1669–1676 |year=2003 |issue=10}}</ref> Limitation of this undesirable reaction is possible by controlling water hardness, detergent load and temperature. The type of glass is an important factor in determining if this effect is a problem. Some dishwashers can reduce this etching effect by automatically dispensing the correct amount of detergent throughout the wash cycle based on the level of water hardness programmed.{{Cn|date=March 2025}}
; Dissolution of lead: Lead in [[lead crystal]] can be converted into a soluble form by the high temperatures and strong alkali detergents of dishwashers, which could endanger the health of subsequent users.<ref>{{cite web|url=http://www.yale.edu/ynhti/curriculum/units/1997/7/97.07.05.x.html |title=''Lead Contamination In Our Environment'' |publisher=Yale.edu |access-date=2012-06-20}}</ref>

===Other materials===
Other materials besides glass are also harmed by the strong detergents, strong agitation, and high temperatures of dishwashers, especially on a hot wash cycle when temperatures can reach {{convert|75|°C|°F|abbr=on}}.<ref name="huffpo">{{Cite web |url=https://www.huffingtonpost.com/2015/05/07/wash-dishes_n_7232216.html |title=You Should Pretty Much NEVER Wash Your Dishes By Hand. Here's Why. |last=Strutner |first=Suzy |date=2015-05-07 |website=Huffington Post |language=en-US |access-date=2017-12-30}}</ref> Aluminium, brass, and copper items will discolor, and light aluminum containers will mark other items they knock into. Nonstick pan coatings will deteriorate. Glossy, gold-colored, and hand-painted items will be dulled or fade. Fragile items and sharp edges will be dulled or damaged from colliding with other items or thermal stress. Sterling silver and pewter will oxidize and discolour from the heat and from contact with metals lower on the [[galvanic series]] such as stainless steel.<ref name="martha">{{Cite web |url=https://www.marthastewart.com/275693/dishwashing-secrets?slide=3408114 |title=Dishwashing Secrets |date=2011-02-02 |website=Martha Stewart |language=en |access-date=2017-12-30}}</ref> Pewter has a low melting point and may warp in some dishwashers. Glued items, such as hollow-handle knives or wooden [[cutting board]]s, will melt or soften in a dishwasher; high temperatures and moisture damage wood. High temperatures damage many plastics, especially in the bottom rack close to an exposed [[heating element]] (many newer dishwashers have a concealed heating element away from the bottom rack entirely). Squeezing plastic items into small spaces may cause the plastic to distort in shape. [[Cast iron]] [[cookware and bakeware|cookware]] is normally seasoned with oil or grease and heat, which causes the oil or grease to be absorbed into the pores of the cookware, thereby giving a smooth relatively non-stick cooking surface which is stripped off by the combination of alkali based detergent and hot water in a dishwasher.{{Cn|date=March 2025}}
 
Knives and other cooking tools that are made of [[carbon steel]], semi-stainless steels like D2, or specialized, highly hardened cutlery steels like ZDP189 corrode in the extended moisture bath of dishwashers, compared to briefer baths of hand washing. Cookware is made of [[austenite|austenitic]] stainless steels, which are more stable.{{Cn|date=March 2025}}
 
Items contaminated by chemicals such as wax, cigarette ash, poisons, mineral oils, wet paints, oiled tools, furnace filters, etc. can contaminate a dishwasher, since the surfaces inside small water passages cannot be wiped clean as surfaces are in hand-washing, so contaminants remain to affect future loads. Objects contaminated by [[solvent]]s may explode in a dishwasher.{{Cn|date=March 2025}}

===Environmental comparison===
Dishwashers use less water, and therefore less fuel to heat the water, than hand washing, except for small quantities washed in wash bowls without running water.<ref>{{Cite news |url=https://www.washingtonpost.com/news/energy-environment/wp/2015/05/05/why-you-shouldnt-wash-your-dishes-by-hand/ |title=Why you shouldn't wash your dishes by hand |last=Mooney |first=Chris |date=2015-05-05 |newspaper=Washington Post |language=en-US |access-date=2017-12-30}}</ref><ref name="star">{{Cite web |url=https://www.energystar.gov/products/appliances/dishwashers/dishwasher_hand_washing |title=Dishwasher vs. Hand Washing Dishes |website=www.energystar.gov |language=en |access-date=2017-12-30 |archive-date=2019-12-12 |archive-url=https://web.archive.org/web/20191212144356/https://www.energystar.gov/products/appliances/dishwashers/dishwasher_hand_washing |url-status=dead }}</ref>

Hand-washing techniques vary by individual. According to a peer-reviewed study in 2003, hand washing and drying of an amount of dishes equivalent to a fully loaded automatic dishwasher (no [[cookware and bakeware|cookware or bakeware]]) could use between {{convert|20|and|300|L|gal}} of water and between 0.1 and 8 kWh of energy, while the numbers for energy-efficient automatic dishwashers were {{convert|15|-|22|L|gal}} and 1 to 2 kWh, respectively. The study concluded that fully loaded dishwashers use less energy, water, and detergent than the average European hand-washer.<ref>{{cite journal |last=Stamminger |first=Rainer |year=2003 |title=A European Comparison of Cleaning Dishes by Hand |journal=Proceedings of EEDAL Conference |url=https://www.landtechnik.uni-bonn.de/forschung/haushaltstechnik/publikationen/eedal-manualdishwashing-ht1/ |access-date=2010-06-13 |archive-date=2011-11-04 |archive-url=https://web.archive.org/web/20111104182244/http://www.landtechnik.uni-bonn.de/forschung/haushaltstechnik/publikationen/eedal-manualdishwashing-ht1 |url-status=dead }}</ref><ref>{{cite web |title=Is a machine more efficient than the hand? |url=http://www.landtechnik-alt.uni-bonn.de/ifl_research/ht_1/EEDAL_03_ManualDishwashing.pdf |last=Stamminger |first=Rainer |publisher=Home Energy |date=May–June 2004 |access-date=2010-06-13 |url-status=dead |archive-url=https://web.archive.org/web/20150701173343/http://www.landtechnik-alt.uni-bonn.de/ifl_research/ht_1/EEDAL_03_ManualDishwashing.pdf |archive-date=2015-07-01 }}</ref> For the automatic dishwasher results, the dishes were not rinsed before being loaded. The study does not address costs associated with the manufacture and disposal of dishwashers, the cost of possible accelerated wear of dishes from the chemical harshness of dishwasher detergent, the comparison for cleaning cookware, or the value of labour saved; hand washers needed between 65 and 106 minutes. Several points of criticism on this study have been raised.<ref>[http://probonostats.wordpress.com/2008/09/24/dishwashing-man-vs-machine/ Dishwashing: man vs. machine.] Yoram Gat, Pro Bono Statistics Weblog (2008)</ref> For example, [[kilowatt hour]]s of electricity were compared against energy used for heating hot water without taking into account possible inefficiencies. Also, inefficient handwashings were compared against optimal usage of a fully loaded dishwasher without manual pre-rinsing that can take up to {{convert|100|L|gal}} of water.<ref>[http://www.joe.org/joe/2003february/rb3.php Dishwashing and Water Conservation: An Opportunity for Environmental Education] {{Webarchive|url=https://web.archive.org/web/20130801113451/http://www.joe.org/joe/2003february/rb3.php |date=2013-08-01 }}. Journal of Extension, Volume 41, Number 1 (2003).</ref>

A 2009 study showed that the microwave and the dishwasher were both more effective ways to clean [[kitchen sponge|domestic sponges]] than handwashing.<ref>{{cite journal |doi=10.1016/j.foodcont.2013.07.026 |volume=35 |title=Hygiene in the home kitchen: Changes in behaviour and impact of key microbiological hazard control measures |journal=Food Control |pages=392–400|year=2014 |last1=Taché |first1=J. |last2=Carpentier |first2=B. }}</ref>