With warmer weather comes more days at the beach and more opportunities to brave the ocean. I’ve never been scuba diving, but I have been around long enough to see divers spit on their masks before going under. The theory is that spit helps the mask from fogging up. Does it really work?
Depends on who you ask, but most sites I visited seemed to side with the spitters. The good folks at ScubeGuide.com wrote, “Saliva works very well as a mask defogger for reasons that have never been adequately explained.”
A blog from AquaViews.net goes into some pretty deep detail on why spit works so well. Masks fog up when the temperature of the inside lens falls “below the dew point of the air inside the mask.” The drop in temperature leads to condensation and then fog. Spit comes in handy because it lowers the “surface tension of a liquid,” in this case the water. The spit “prevents water droplet formation.”
AquaViews.net puts it this way: “The water from the condensation does not mound up as beads or droplets but, instead breaks to form bigger droplets that just roll away into the mask. So the water condensation on the insides of the mask don’t adhere to the glass but instead break up and roll down into the mask itself, giving the scuba diver clear vision.”
You could something else like baby shampoo and it would be just as effective. But why bother when saliva is always at the ready?
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