How does mask anti-fog work?

[Scubakevdm]

We can't use spit in the pool due to the usual rules against this.

Crybabies.

 

[rcohn]

I little trick I learned from the divemasters in Thailand is to use baby shampoo. ..... It smells reasonably good too. > Jimi

I've been using baby shampoo for several years, it works very well. You want a "no tears" type in case you get some residue in your eyes, hence no adult shampoo or soap.

Ralph

 

[Phaethon]

As a motorcyclist I suffered from visor fogging in cold and/or rainy days. Like scuba, there are many propriety anti-fog preparations, but the best solution was to smear a small amount of washing-up detergent on the inside.

Scuba defog foams like detergent also, but I would image that it is very mild because, during a mask flood, the chemical is more likely to reach the eye and cause irritation than would be likely in a MC helmet.

Cheers,

K.

 

[WarmWaterDiver]

The key science word is "surfactant". Scubakevdm has captured this elegantly in his first post on this thread. This is also why the soap "lifts off the grease" from the dirty dishes (for dishwashing soap), hair (for shampoo), etc. as it's conventional wisdom "oil & water don't mix" (I won't go in depth in discussions of emulsions here). Saliva in this case also works as a surfactant - ask any feline.

 

[Canucklehead]

I will let the attached pic tell the story....

 

[H2Andy]

why is it that i am always eating when i read one of these posts?

the whale poop picture was by far the worst, but this one comes close...

 

[armyscuba]

I little trick I learned from the divemasters in Thailand is to use baby shampoo. It seems to work as well as any of the defogs or spit (maybe even Scubakevdm's spit, I think.... It smells reasonably good too. > Jimi

I'll agree with You on this one Jimisurf..My MSDT showed Me that same trick..Johnson's Baby Shampoo and water, I put it in a spray bottle, best of all it's cheap $1.59 and makes dozens of bottles..it works Great..and no tears...ha...

 

[H2Andy]

aha! but you fail to mention the ratio of baby shampoo to water...

 

[DennisW]

I use dishwashing detergent (surfactant). Dawn works, but any type of detergent works. Baby Shampoo is a detergent and since it doesn't sting if it gets in your eyes, even better. I store my mask with the detergent smeared on the lenses. When I get ready to go diving, I use some more and then just before entering the water, I wash out the detergent (I make sure I get all of it out). Sometimes, I add spit just for good measure. Mostly, this works. The trick is to get the inside of your mask very clean and the water particles will not stick to the surface.

 

[-=>Larry<=-]

A most enjoyable thread, My particular religion is Baby Shampoo [50% in water], with spit as backup anytime I can't find that little bottle....but..
<lecture mode on>
The property involved is Surface Tension. Detergents as a subset of the surfactants have the property of reducing the surface tension of the water to the point that it forms a smooth coating over near anything [generally hydrophilic] rather than beading up into droplets, the extreme case of which is a hydrophobic surface, where the water is in a bead, no matter what. That fog on your mask or visor is tiny, tiny beads of water that refract the light in all sorts of directions making vision near impossible. With a nice surfactant - the water simply forms a layer that flows off as soon as there's enough of it <lecture mode off>
I enjoy running around classes I help with and donating water/shampoo - especially to the students that just bought the 5$ [?] bottle of "DeFog"