How Does Spit Defog a Snorkel Mask?

I guess it matters on whose mask you're spitting in. Is it your mask? Your friends? Is it a snorkel mask that you rented as part of a cheap set from the snorkel guide or beach? It really just matters.

We've all seen it, though. No matter how nasty it may appear, people can be seen spitting into their snorkel masks and then rubbing it around with their fingers to make sure all that saliva is spread to every nook and cranny of the inside of the mask. I've never seen anyone liking their entire mask lens but I'm sure that it happens. (Anyone who shares that kind of video in the comments below will get a shout out!)

Where to Spit in the Snorkel Mask

I guess that would be the number one point that we start off right away in this article: You spit on the inside of your snorkel mask. Not the outside. That would just be weird. However, it is not impossible to imagine a person thinking that spitting on the outside of their snorkel mask will suffice in keeping the fog away.

And while we're on the subject let's also dwell upon this little tidbit of information: While spitting seems to work well enough for defogging snorkel masks there are other, less saliva-containing items and methods for defogging snorkel masks.

But that's all just digression at this point. We could debate whether spitting in a snorkel mask is just like spitting in your eye-glasses to keep them from fogging up when you come in from the cold. If spitting is socially acceptable on a beach or catamaran anchored on some tropical coral then why is it not okay to spit into your eye glasses when you walk in to a warm, cozy house on a winter evening.

Ah, well. Anyway...onto the spit...err...meat of this story.

A dew point is the atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form. So, yeah, as you can see the dew point has a lot to do with snorkel masks fogging up.

I'm also going to go ahead and assume that morning dew has something to do with this dew point thing. However, if you don't agree, then dew let me know.

I've actually heard someone scream the title of this section (Aaah!! What does it keep fogging up!?) into their snorkel tubes as I was videoing a sea turtle on a recent snorkeling adventure in Hawaii. Funny? Yes. However, it's also completely terrifying when you hear it screamed through the tube, underwater, in a high-pitch tone that can only be accomplished when screaming with frustration into a snorkel tube while submerged.

Still, though, it's a good question.

Why Do Snorkel Masks Fog Up At All?

Your snorkel mask will fog up when the inside (the part facing your...errr...face) is at temperature which is below the dew point (see tip titled "what the heck is a dew point" up and to the right) of the air that is inside the mask.

Okay, here's how this works: You have ocean water that is, while nice and tropical (like bathwater, my motha' woulda' said) is still cooler than the air that you're breathing out of your lungs, through your nose, and into the mask. The water cools the snorkel mask lens, you warm the air inside the mask with your dragon breath...and voila! There you have it! The temperature of the snorkel mask lens is cooler than the air in the mask.

But that's not all, kids! Nope. There's more to play here. The science is unbelievable! Check this out:

The inside of your snorkel mask, no matter how smooth it feels (like a baby's bottom, my motha' woulda' said) has tiny, microscopic, potholes, depressions, bumps and dimples on it...sort of like a golf ball. So, when you breath there is actually moisture in the mask and in your breath, actually. Those little globules of moisture start to become very attracted (like a bee to a flower, my motha' woulda' said) to those little indentations and depressions on the inside of the snorkel mask. When that moisture starts to gloop into those depressions it gathers and forms...FOG on the inside of the mask.

A surfactant is a substance that tends to reduce the surface tension of a liquid in which it is dissolved. So, as explained to the left, the surfactant prevents the water and moisture from globbing together and causing fog or condensation on inside of your snorkel mask.

You're saying, "Listen jerk, I was born during the day but it wasn't yesterday. How the heck do you prevent moisture on the inside of your mask by spitting into it, smearing it around, and then sticking it to your face? Huh, genius?"

Ah-ha! Uhm...It doesn't actually. Spit doesn't prevent moisture in a snorkel mask any better than chewing gum prevents nicotine cravings. All the spit does is to prevent the moisture from dispersing into tiny particles and instead forces it to stay larger and fall to the bottom of the mask.

Here's how Spit in a Snorkel Mask Helps Prevent Fog

Spit acts as a surfactant on the inside of your snorkel mask. (See the tip module to the right titles "what the heck is a surfactant" up and to the right).

Basically, surfactants prevent the water globules from gathering together and sticking to the inside of your snorkel mask and, thus, preventing the fog on the inside of your mask and reducing the chances of your screaming into your snorkel tube and terrifying those around you.

If all that moisture were to really disappear then that would be magic ("like a Harry Houdini",my motha' woulda' said). Instead of forming and sticking together the moisture is prevented from being so tiny and starts to glob into larger bits. Those larger bits are to heavy to stick to the inside of the mask and tend to settle down on the bottom. Quality snorkel masks have purge valves so that you can just push the moisture out of the bottom of the mask by way of a good snort.

No.

Spit is, in most cases, a valuable commodity inside mouth and it seems to never really be enough to go around in the mask. Commercial defoggers, while not free or as gross as spit are actually better to prevent fogging in snorkel masks and easier to use. Plus, squirting a little defogger from a bottle into your mask and having to constantly create saliva and spit will keep you in good on your snorkeling date.

A commercial defogger is the best route to take if trying to keep your snorkel mask clean. Look at this stuff to the right! It's called "Spit". Ironic?

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