Anti-fog agents, also known asanti-fogging agents and treatments, are chemicals that prevent thecondensation ofwater in the form of smalldroplets on a surface which resemblefog. They are one of manyadditives used in the production of plastics.[1]
Anti-fog agents were developed byNASA during theProject Gemini, for use on helmetvisors. DuringGemini 9A, in June 1966, AstronautEugene A. Cernan tested NASA's firstspace suit, and discovered during thespace walk that his helmet visor fogged, among other issues.[2] Cernan's suit was tested using theSpacecraft 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 ofcondensation. Later Gemini flights all included the anti-fog solution, for application prior to the space walk occurring.[3][4]
Anti-fog agents are available asspraysolutions,creams andgels, andwet wipes, while more resistantcoatings are often applied during complexmanufacturing processes. Anti-fog additives can also be added to plastics where theyexude from the inside to the surface.[5]
Most commercial anti-fog agents aresurfactants that minimize the surface tension of the water.Ethoxylates andpolysiloxanes are typical.[1]
Many other substances have been used as anti-fog agents including home-based recipes containingdetergents.
One method to prevent fogging is to apply a thin film ofdetergent, but this method is criticized because detergents are designed to bewater-soluble and they cause smearing.[6] Divers often use saliva,[7] which is a commonly known and effective anti-fogging agent.[8]
Ademister is a substance applied to transparent surfaces to stop them from becoming fogged with mist deposit, often referred to as fog.Scuba divers oftenspit 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 havesilicone on them from the manufacturing process,[7] so it is recommended to clean the lenses with an appropriate mask scrub, then rinse the mask and then apply a demister solution.
