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.[1]
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.[2] 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.[3][4]
Application
Anti-fog agents are available as
spraysolutions,
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.[5]
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.[6] Divers often use saliva,[7] which is a commonly known and effective anti-fogging agent.[8]
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 and
Underwater Hockey players 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, so it is recommended to clean the lenses with an appropriate mask scrub, then rinse the mask and then apply a demister solution.
Fogging (photography) – Secondary exposure of undeveloped film to light, for fogging artifacts in photography
References
^
abStevens, Malcolm P. (1993). "Polymer Additives: III. Surface Property and Processing Modifiers". Journal of Chemical Education. 70 (9): 713.
Bibcode:
1993JChEd..70..713S.
doi:
10.1021/ed070p713.