[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] 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.
[5] Most commercial anti-fog agents are surfactants that minimize the surface tension of the water.
Scuba divers often spit into their masks and then wash the surface quickly with water to prevent mist buildup that can impair vision.