I’m sure anyone who has ever owned or used a scuba mask or snorkel mask knows that they tend to get very foggy. This is very annoying because the very reason you are using the mask is to see underwater and the fog prevents that. But, have you ever wondered why scuba masks fog up?
Well, wonder no longer. In this article I will give you a mini-science lesson explaining why scuba diving masks fog up. If you stick around, I will also tell you some strategies to prevent fogging. But, keep in mind that no strategy will completely remove fog.
Ok, so why exactly does fog build up in your scuba mask? Well, first you will need to know a little background information about air. I’m sure you have come across the term humidity in your everyday life. Basically, humidity refers to minuscule particles of water that are in the air. Since your body contains a lot of water, your breath is very humid. Once you put your mask on, you tend to exhale through your nose. This adds more moisture to the air inside the mask.
So now that you know the basics of humidity, it is time to explain what the fog really is. The fog you see inside your scuba diving mask is condensed droplets of water from the air inside the mask. Have you ever noticed that, when you pour cold water into a warm glass, droplets begin to form on the outside of the glass? This happens because the water rapidly cools the glass and the droplets form when the warm air surrounding the glass comes in contact with the cool glass. This same process happens inside your mask. The water outside your mask cools the glass and the warm air inside your mask comes in contact with the glass lenses. This is how fog is formed.
But how does fog actually form? Well, my good sir/madam, fog forms because of something called surface tension. Basically, surface tension is the ability of water molecules to hold themselves tightly together. Think of it this way, one molecule sees another and is all like “Hey, man this glass is pretty damn cold, let’s bunch together to stay warm.” And the other guy responds with “Dude……good idea.” Repeat this step oh, I don’t know, maybe a million times and you got yourself a little speck of fog or a water droplet. While horribly inaccurate, this is basically what surface tension is like.
And that is how fog forms on your scuba mask. So, how do you get rid of it? Well, the most common form of scuba mask defog is simply spitting on the lenses of your mask before you put it on. Your spit forces its way between the bonds the water molecules form and causes them to break. This causes the water molecules to spread out. This eliminates the fog effect and causes large, spread out droplets to form rather than a blanket of fog.
That’s the only method I am going to list in this article. I will be writing another article dedicated to fog preventing methods so stay tuned.