# Anti-fog
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{{short description|Chemicals that prevent the condensation of water as small droplets on a surface }}
'''Anti-fog''' agents, also known as '''anti-fogging''' agents and treatments, are chemicals that prevent the [condensation](/source/condensation) of [water](/source/water) in the form of small [droplets](/source/droplets) on a surface which resemble [fog](/source/fog). They are one of many [additives](/source/Plastic) used in the production of plastics.[{{cite journal |doi=10.1021/ed070p713 |title=Polymer Additives: III. Surface Property and Processing Modifiers |date=1993 |last1=Stevens |first1=Malcolm P. |journal=Journal of Chemical Education |volume=70 |issue=9 |page=713 |bibcode=1993JChEd..70..713S }}]
==Development==
Anti-fog agents were developed by [NASA](/source/NASA) during the [Project Gemini](/source/Project_Gemini), for use on helmet [visor](/source/visor)s. During [Gemini 9A](/source/Gemini_9A), in June 1966, Astronaut [Eugene A. Cernan](/source/Eugene_A._Cernan) tested NASA's first [space suit](/source/space_suit), and discovered during the [space walk](/source/space_walk) that his helmet visor fogged, among other issues.[{{Cite book|url=https://history.nasa.gov/SP-4219/Chapter13.html|access-date=February 15, 2010|title=From Engineering Science To Big Science|chapter="More Favored than the Birds": The Manned Maneuvering Unit in Space|series=[The NASA History Series](/source/The_NASA_History_Series)|year=1998|first=Anne|last=Millbrooke|editor-first=Pamela E.|editor-last=Mack| archive-url= https://web.archive.org/web/20100311155905/https://history.nasa.gov/SP-4219/Chapter13.html| archive-date= 11 March 2010 | url-status= live}}] Cernan's suit was tested using the [Spacecraft 9 life support system](/source/Spacecraft_9_life_support_system) after the flight, when it was discovered that a small patch of the visor treated with an anti-fog solution remained clear of [condensation](/source/condensation). Later Gemini flights all included the anti-fog solution, for application prior to the space walk occurring.[{{Cite book|url=https://history.nasa.gov/SP-4203/ch14-6.htm|access-date=February 15, 2010|title=On the Shoulders of Titans: A History of Project Gemini|chapter=An Angry Alligator|series=[The NASA History Series](/source/The_NASA_History_Series)|year=1977|first1=Barton C.|last1=Hacker|first2=James M.|last2=Grimwood| archive-url= https://web.archive.org/web/20100311114534/https://history.nasa.gov/SP-4203/ch14-6.htm| archive-date= 11 March 2010 | url-status= live}}][{{Cite web|url=http://www.jamesmskipper.us/PHOTOS1.html|access-date=February 15, 2010|title=My Experience as a Space Suit Test Subject}}]
==Application==
Anti-fog agents are available as [spray](/source/spray_(liquid_drop)) [solution](/source/Solution_(chemistry))s, [cream](/source/Cream_(pharmaceutical))s and [gel](/source/gel)s, and [wet wipe](/source/wet_wipe)s, while more resistant [coating](/source/coating)s are often applied during complex [manufacturing](/source/manufacturing) processes. Anti-fog additives can also be added to plastics where they [exude](/source/exude) from the inside to the surface.[{{Cite web|url=http://composite.about.com/library/glossary/a/bldef-a367.htm|access-date=February 15, 2010|title=Antifogging agents for plastics|work=[About.com](/source/About.com)|publisher=[The New York Times Company](/source/The_New_York_Times_Company)|archive-date=October 21, 2005|archive-url=https://web.archive.org/web/20051021092806/http://composite.about.com/library/glossary/a/bldef-a367.htm|url-status=dead}}]
===Agents===
Most commercial anti-fog agents are [surfactant](/source/surfactant)s that minimize the surface tension of the water. [Ethoxylates](/source/Ethoxylation) and [polysiloxane](/source/polysiloxane)s are typical.[
Many other substances have been used as anti-fog agents including home-based recipes containing [detergent](/source/detergent)s.
One method to prevent fogging is to apply a thin film of [detergent](/source/detergent), but this method is criticized because detergents are designed to be [water-soluble](/source/Solubility) and they cause smearing.][{{Cite web|url=http://www.webbikeworld.com/r2/motorcycle-helmet-visor-anti-fog/salclear/|access-date=February 15, 2010|title=Salclear Motorcycle Helmet Visor Anti-Fog|author=Rick K.|author2=Burn|work=[webBikeWorld.com](/source/webBikeWorld.com)|publisher=[webWorld International](/source/webWorld_International)| archive-url= https://web.archive.org/web/20100131041215/http://www.webbikeworld.com/r2/motorcycle-helmet-visor-anti-fog/salclear/| archive-date= 31 January 2010 | url-status= live}}] Divers often use saliva,[{{Cite web|url=http://www.scubadoctor.com.au/care-mask.htm|access-date=February 15, 2010|title=Mask Care - Have a clear view every dive|work=[The Scuba Doctor](/source/The_Scuba_Doctor)|publisher=[The Scuba Doctor](/source/The_Scuba_Doctor)}}] which is a commonly known and effective anti-fogging agent.[{{Cite web|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F5173804|access-date=February 15, 2010|title=Mirror and method of mounting the same|first=Kent|last=Dogey|date=July 26, 1991}}]
==Uses==
===Underwater diving===
A '''demister''' is a substance applied to transparent surfaces to stop them from becoming fogged with mist deposit, often referred to as fog. [Scuba divers](/source/Scuba_diving) often [spit](/source/saliva) into their masks and then wash the surface quickly with water to prevent mist buildup that can impair vision. Several products are commercially available such as Sea Drops that are generally more effective. New masks lenses still have [silicone](/source/silicone) on them from the manufacturing process,