Editing Capillary action (section)

== Examples ==
In the built environment, evaporation limited capillary penetration is responsible for the phenomenon of [[damp (structural)|rising damp]] in [[concrete]] and [[masonry]], while in industry and diagnostic medicine this phenomenon is increasingly being harnessed in the field of [[paper-based microfluidics]].<ref name="cappen" />

In physiology, capillary action is essential for the drainage of continuously produced [[tears|tear]] fluid from the eye. Two canaliculi of tiny diameter are present in the inner corner of the [[eyelid]], also called the [[Nasolacrimal duct|lacrimal ducts]]; their openings can be seen with the naked eye within the lacrymal sacs when the eyelids are everted.{{cn|date=January 2025}}

Wicking is the absorption of a liquid by a material in the manner of a candle wick.{{cn|date=January 2025}}

[[Paper towel]]s absorb liquid through capillary action, allowing a [[Fluid statics|fluid]] to be transferred from a surface to the towel. The small pores of a [[sponge (tool)|sponge]] act as small capillaries, causing it to absorb a large amount of fluid. Some textile fabrics are said to use capillary action to "wick" sweat away from the skin. These are often referred to as [[layered clothing#wicking-materials|wicking fabrics]], after the capillary properties of [[candle]] and lamp [[Candle wick|wicks]].{{cn|date=January 2025}}

Capillary action is observed in [[thin layer chromatography]], in which a solvent moves vertically up a plate via capillary action. In this case the pores are gaps between very small particles.{{cn|date=January 2025}}

Capillary action draws [[ink]] to the tips of [[fountain pen]] [[nib (pen)|nib]]s from a reservoir or cartridge inside the pen.{{cn|date=January 2025}}

With some pairs of materials, such as [[mercury (element)|mercury]] and glass, the [[intermolecular force]]s within the liquid exceed those between the solid and the liquid, so a [[wikt:convex|convex]] meniscus forms and capillary action works in reverse.{{cn|date=January 2025}}

In [[hydrology]], capillary action describes the attraction of water molecules to soil particles. Capillary action is responsible for moving [[groundwater]] from wet areas of the soil to dry areas. Differences in soil [[water potential|potential]] (<math>\Psi_m</math>) drive capillary action in soil.{{cn|date=January 2025}}

A practical application of capillary action is the capillary action siphon. Instead of utilizing a hollow tube (as in most siphons), this device consists of a length of cord made of a fibrous material (cotton cord or string works well). After saturating the cord with water, one (weighted) end is placed in a reservoir full of water, and the other end placed in a receiving vessel. The reservoir must be higher than the receiving vessel.<ref>{{Cite web |title=Capillary Action and Water {{!}} U.S. Geological Survey |url=https://www.usgs.gov/special-topics/water-science-school/science/capillary-action-and-water |access-date=2024-04-29 |website=www.usgs.gov}}</ref> A related but simplified capillary siphon only consists of two hook-shaped stainless-steel rods, whose surface is hydrophilic, allowing water to wet the narrow grooves between them.<ref>{{cite journal |last1=Wang |first1=Kaizhe |last2=Sanaei |first2=Pejman |last3=Zhang |first3=Jun |last4=Ristroph |first4=Leif |title=Open capillary siphons |journal=Journal of Fluid Mechanics |date=10 February 2022 |volume=932 |doi=10.1017/jfm.2021.1056 |bibcode=2022JFM...932R...1W }}</ref> Due to capillary action and gravity, water will slowly transfer from the reservoir to the receiving vessel. This simple device can be used to water houseplants when nobody is home. This property is also made use of in the [[Automatic lubricator#Wick feed lubricator|lubrication of steam locomotives]]: wicks of [[worsted|worsted wool]] are used to draw oil from reservoirs into delivery pipes leading to the [[Bearing (mechanical)|bearings]].<ref>{{cite book |last1=Ahrons |first1=Ernest Leopold |title=Lubrication of Locomotives |date=1922 |publisher=Locomotive Publishing Company |location=London |oclc=795781750 |page=26}}</ref>

=== In plants and animals ===

Capillary action is seen in many plants, and plays a part in [[transpiration]]. Water is brought high up in trees by branching; evaporation at the leaves creating depressurization; probably by [[osmotic pressure]] added at the roots; and possibly at other locations inside the plant, especially when gathering humidity with [[air root]]s.<ref>[http://npand.wordpress.com/2008/08/05/tree-physics-1/ Tree physics] {{webarchive|url=https://web.archive.org/web/20131128125015/http://npand.wordpress.com/2008/08/05/tree-physics-1/ |date=2013-11-28 }} at "Neat, Plausible And" scientific discussion website.</ref><ref>[http://www.wonderquest.com/Redwood.htm Water in Redwood and other trees, mostly by evaporation] {{webarchive|url=https://web.archive.org/web/20120129122454/http://www.wonderquest.com/Redwood.htm |date=2012-01-29 }} article at wonderquest website.</ref><ref>{{cite journal |last1=Poudel |first1=Sajag |last2=Zou |first2=An |last3=Maroo |first3=Shalabh C. |title=Disjoining pressure driven transpiration of water in a simulated tree |journal=Journal of Colloid and Interface Science |date=June 2022 |volume=616 |pages=895–902 |doi=10.1016/j.jcis.2022.02.108 |pmid=35259719 |arxiv=2111.10927 |bibcode=2022JCIS..616..895P }}</ref>

Capillary action for uptake of water has been described in some small animals, such as ''[[Ligia exotica]]''<ref>{{cite journal |vauthors=Ishii D, Horiguchi H, Hirai Y, Yabu H, Matsuo Y, Ijiro K, Tsujii K, Shimozawa T, Hariyama T, Shimomura M|title=Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces |journal=Scientific Reports |volume=3 |page=3024 |date=October 23, 2013 |doi=10.1038/srep03024 |pmid=24149467 |pmc=3805968 |bibcode=2013NatSR...3.3024I }}</ref> and ''[[Moloch horridus]]''.<ref>{{cite journal |last1=Bentley |first1=P. J. |last2=Blumer |first2=W. F. C. |title=Uptake of Water by the Lizard, Moloch horridus |journal=Nature |date=May 1962 |volume=194 |issue=4829 |pages=699–700 |doi=10.1038/194699a0 |pmid=13867381 |bibcode=1962Natur.194..699B }}</ref>