Editing Calcium hydroxide (section)

==Uses==
Calcium hydroxide is commonly used to prepare [[lime mortar]].

One significant application of calcium hydroxide is as a [[flocculation|flocculant]], in water and [[sewage treatment]]. It forms a fluffy charged solid that aids in the removal of smaller particles from water, resulting in a clearer product. This application is enabled by the low cost and low toxicity of calcium hydroxide. It is also used in fresh-water treatment for raising the pH of the water so that pipes will not corrode where the base water is acidic, because it is self-regulating and does not raise the pH too much.{{cn|date=September 2023}}

Another large application is in the paper industry, where it is an intermediate in the reaction in the production of sodium hydroxide. This conversion is part of the ''causticizing'' step in the [[Kraft process#Recovery process|Kraft process]] for making pulp. In the causticizing operation, burned lime is added to ''[[green liquor]]'', which is a solution primarily of [[sodium carbonate]] and [[sodium sulfate]] produced by dissolving ''smelt'', which is the molten form of these chemicals from the recovery furnace.<ref name=G&W>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. {{ISBN|0-7506-3365-4}}.</ref>

In [[orchard]] crops, calcium hydroxide is used as a fungicide. Applications of 'lime water' prevent the development of cankers caused by the fungal pathogen ''[[Neonectria galligena]]''. The trees are sprayed when they are dormant in winter to prevent toxic burns from the highly reactive calcium hydroxide. This use is authorised in the European Union and the United Kingdom under Basic Substance regulations.<ref>{{Cite web |last=European Union |date=13 May 2015 |title=COMMISSION IMPLEMENTING REGULATION (EU) 2015/762 of 12 May 2015 approving the basic substance calcium hydroxide in accordance with Regulation (EC) No 1107/2009 of the European Parliament and of the Council concerning the placing of plant protection products on the market, and amending the Annex to Commission Implementing Regulation (EU) No 540/2011 |url=https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32015R0762&from=RO |access-date=12 May 2022}}</ref>

Calcium hydroxide is used in dentistry, primarily in the specialty of [[endodontics]] due to its antibacterial properties and induction of [[hard-tissue]] deposition.<ref>{{cite journal | url=https://pubmed.ncbi.nlm.nih.gov/21535021/ | pmid=21535021 | date=2011 | last1=Mohammadi | first1=Z. | last2=Dummer | first2=P. M. | title=Properties and applications of calcium hydroxide in endodontics and dental traumatology | journal=International Endodontic Journal | volume=44 | issue=8 | pages=697–730 | doi=10.1111/j.1365-2591.2011.01886.x }}</ref>

===Food industry===
Because of its low [[toxicity]] and the mildness of its basic properties, slaked lime is widely used in the [[food industry]],

* In USDA certified food production in plants and livestock<ref>{{Cite web |url=https://www.ams.usda.gov/sites/default/files/media/Lime%20Hydrated%20TR%202015.pdf |title=Hydrated Lime: Technical Evaluation Report |last=Pesticide Research Institute for the USDA National Organic Program |date=23 March 2015 |website=Agriculture Marketing Services |access-date=17 July 2019}}</ref>
* To clarify raw juice from [[sugarcane]] or [[sugar beet]]s in the [[sugar industry]] (see [[carbonatation]])
* To process water for alcoholic beverages and soft drinks
* To increase the rate of [[Maillard reaction]]s ([[pretzel]]s)<ref name="nordicfoodlab">{{cite web |last1=Borsook |first1=Alec |title=Cooking with Alkali |url=https://nordicfoodlab.org/blog/2015/08/cooking-with-alkali/ |website=Nordic Food Lab |date=August 6, 2015}}</ref>
* [[pickling|Pickle]] cucumbers and other foods
* To make Chinese [[century egg]]s
* In maize preparation: removes the cellulose hull of maize kernels (see [[nixtamalization]])
* To clear a [[brine]] of [[carbonate]]s of calcium and [[magnesium]] in the manufacture of salt for food and pharmaceutical uses
* In fortifying (Ca supplement) fruit drinks, such as orange juice, and [[infant formula]]
* As a substitute for [[baking soda]] in making ''[[papadam]]''
* In the removal of carbon dioxide from controlled atmosphere produce storage rooms
* In the preparation of mushroom growing substrates<ref>{{cite web |title=Preparation of Mushroom Growing Substrates |url=https://namyco.org/preparation_of_substrates.php |website=North American Mycological Association |access-date=8 July 2021}}</ref>

==== Native American uses ====
[[File:Nixtamalized Corn maize El Salvador recipe.jpg|thumb|left|Dry untreated maize (left), and treated maize (right) after boiling in water with calcium hydroxide (15{{nbsp}}ml, or 1{{nbsp}}tbsp, lime for 500{{nbsp}}g of corn) for 15 minutes]] In [[Nahuatl]], the language of the [[Aztecs]], the word for calcium hydroxide is ''nextli''. In a process called ''[[nixtamalization]]'', [[maize]] is cooked with nextli to become {{lang|es|nixtamal}}, also known as [[hominy]]. Nixtamalization significantly increases the bioavailability of [[Niacin (nutrient)|niacin]] (vitamin B<sub>3</sub>), and is also considered tastier and easier to digest. Nixtamal is often ground into a flour, known as ''[[masa]]'', which is used to make tortillas and tamales.{{cn|date=September 2023}}
Limewater is used in the preparation of maize for [[corn tortillas]] and other culinary purposes using a process known as [[nixtamalization]]. Nixtamalization makes the niacin nutritionally available and prevents [[pellagra]].<ref>{{cite journal |url=https://www.researchgate.net/publication/228453826 |title=Nixtamalization, a Mesoamerican technology to process maize at small-scale with great potential for improving the nutritional quality of maize based foods |last=Wacher |first=Carmen |date=2003-01-01 |journal=Food Based Approaches for a Healthy Nutrition in Africa |url-status=live |archive-url=https://web.archive.org/web/20180305202539/https://www.researchgate.net/publication/228453826_Nixtamalization_a_Mesoamerican_technology_to_process_maize_at_small-scale_with_great_potential_for_improving_the_nutritional_quality_of_maize_based_foods |archive-date=2018-03-05}}</ref> Traditionally lime water was used in [[Taiwan]] and [[China]] to preserve [[persimmon]] and to remove [[wikt:astringency|astringency]].<ref>{{Cite book |last=Hu |first=Shiu-ying |url=https://www.worldcat.org/oclc/58840243 |title=Food plants of China |date=2005 |publisher=Chinese University Press |isbn=962-201-860-2 |location=Hong Kong |oclc=58840243}}</ref>{{Rp|page=623}}

In chewing [[coca leaves]], calcium hydroxide is usually chewed alongside to keep the [[alkaloid]] [[stimulant]]s chemically available for [[absorption (small intestine)|absorption]] by the body. Similarly, Native Americans traditionally chewed tobacco leaves with calcium hydroxide derived from burnt mollusc shells to enhance the effects. It has also been used by some indigenous South American tribes as an ingredient in ''[[yopo]]'', a psychedelic snuff prepared from the beans of some ''[[Anadenanthera]]'' species.<ref>{{cite journal |author=de Smet, Peter A. G. M. |title=A multidisciplinary overview of intoxicating snuff rituals in the Western Hemisphere |doi=10.1016/0378-8741(85)90060-1 |pmid=3887041 |journal=Journal of Ethnopharmacology |volume=3 |issue=1 |year=1985 |pages=3–49}}</ref>

====Asian uses====
Calcium hydroxide, locally known as ''chuna'', ''choona'' or ''soon'', is typically added to a bundle of [[areca nut]] and [[betel]] leaf called "[[paan]]" to keep the [[alkaloid]] [[stimulant]]s chemically available to enter the bloodstream via [[sublingual]] absorption.

''Choona'' is a key ingredient in [[Petha]], contributing to its characteristic crunchy and firm texture.

It is used in making ''[[naswar]]'' (also known as ''nass'' or ''niswar''), a type of dipping tobacco made from fresh tobacco leaves, ''Choona'', and wood ash. <!--[[calcium oxide]] plays an important role in making a ''naswar''.--> It is consumed most in the [[Pashtun people|Pathan]] diaspora, [[Afghanistan]], [[Pakistan]], [[India]] and [[Bangladesh]]. Villagers also use calcium hydroxide to [[Whitewash|paint their mud houses]] in Afghanistan, Pakistan and India.

===Hobby uses===
In buon [[fresco]] painting, limewater is used as the colour solvent to apply on fresh plaster. Historically, it is known as the paint [[whitewash]].
[[File:Dying Gaul (casting in Pushkin museum) 04 by shakko.jpg|thumb|Closeup of cast of ''The Dying Gaul'', showing distinctive hairstyle, supposedly derived from washing in limewater]]

Limewater is widely used by marine aquarists as a primary supplement of [[calcium]] and [[alkalinity]] for reef aquariums. [[Coral]]s of order [[Scleractinia]] build their [[endoskeleton]]s from [[aragonite]] (a [[Polymorphism (materials science)|polymorph]] of calcium carbonate). When used for this purpose, limewater is usually referred to as ''Kalkwasser''. It is also used in [[tanning (leather)|tanning]] and making [[parchment]]. The lime is used as a dehairing agent based on its alkaline properties.<ref>''The Nature and Making of Parchment'' by Ronald Reed {{ISBN?}}</ref>

=== Personal care and adornment ===
Treating one's hair with limewater causes it to stiffen and bleach, with the added benefit of killing any lice or mites living there. [[Diodorus Siculus]] described the [[Celts]] as follows:
"Their aspect is terrifying... They are very tall in stature, with rippling muscles under clear white skin. Their hair is blond, but not only naturally so: they bleach it, to this day, artificially, washing it in lime and combing it back from their foreheads. They look like wood-demons, their hair thick and shaggy like a horse's mane. Some of them are clean-shaven, but others – especially those of high rank, shave their cheeks but leave a moustache that covers the whole mouth...".<ref>{{Cite web|url=http://exploringcelticciv.web.unc.edu/diodorus-siculus-library-of-history/|title = Diodorus Siculus, Library of History &#124; Exploring Celtic Civilizations}}</ref><ref>{{cite web|url=https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Diodorus_Siculus/5B*.html|title=Diodorus Siculus – Book V, Chapter 28|website=penelope.uchicago.edu|language=english|access-date=2017-11-12}}</ref>

Calcium hydroxide is also applied in a leather process called [[Liming (leather processing)|liming]].