{{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 of water in the form of small droplets on a surface which resemble fog. They are one of many additives used in the production of plastics.<ref name=JCE>{{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 }}</ref>
==Development== Anti-fog agents were developed by NASA during the Project Gemini, for use on helmet visors. During Gemini 9A, in June 1966, Astronaut Eugene A. Cernan tested NASA's first space suit, and discovered during the space walk that his helmet visor fogged, among other issues.<ref>{{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|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}}</ref> Cernan's suit was tested using the 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. Later Gemini flights all included the anti-fog solution, for application prior to the space walk occurring.<ref>{{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|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}}</ref><ref>{{Cite web|url=http://www.jamesmskipper.us/PHOTOS1.html|access-date=February 15, 2010|title=My Experience as a Space Suit Test Subject}}</ref>
==Application== Anti-fog agents are available as spray solutions, creams and gels, and wet wipes, while more resistant coatings are often applied during complex manufacturing processes. Anti-fog additives can also be added to plastics where they exude from the inside to the surface.<ref name="plastics">{{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|publisher=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}}</ref>
===Agents=== Most commercial anti-fog agents are surfactants that minimize the surface tension of the water. Ethoxylates and polysiloxanes are typical.<ref name=JCE/>
Many other substances have been used as anti-fog agents including home-based recipes containing detergents.
One method to prevent fogging is to apply a thin film of detergent, but this method is criticized because detergents are designed to be water-soluble and they cause smearing.<ref>{{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|publisher=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}}</ref> Divers often use saliva,<ref name=":0">{{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|publisher=The Scuba Doctor}}</ref> which is a commonly known and effective anti-fogging agent.<ref>{{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}}</ref>
==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 often spit 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 on them from the manufacturing process,<ref name=":0" /> so it is recommended to clean the lenses with an appropriate mask scrub, then rinse the mask and then apply a demister solution.
==See also== {{portal|Underwater diving}} * {{annotated link|Fog}} * {{annotated link|Fogging (photography)}}, for fogging artifacts in photography
==References== {{Reflist}}
{{Underwater diving|divequ}}
Category:Automotive accessories Category:Glass coating and surface modification Category:NASA spin-off technologies Category:Plastics additives