How does mask anti-fog work?

[ChrisA]

I figure the reason a mask fogs up is that the inside of the lens is at a tempure below the dew point of the air inside the mask. So water
condenses on the inside of the lens. So how does de-fog (spit or
whatever) prevent this?

My first guess is that the stuff (spit, 500PSU, kelp juice....) afftects the water surface tension alowing the litle droplets to merge and form big droplets that roll of the lens, Or maybe it makes the lens less "sticky" so the condensed water rolls off.

I really don't even know why the condensed water on the inside of the lens stays in place Perhaps the antifog prevides a hydrophobic coating.

I could go on and propose many theories but maybe some one knows the answer.

[MechDiver]

A mask will fog due to particles on the inside of the lens. Antifog cleans the lens so there is nothing for the condensation to adhere to. All I have ever used is spit. As long as you clean the glass, it doesn't matter what you use.

MD

[H2Andy]

what a great question! it had never occurred to me to ask...

and thanks for the quick answer, MechDiver

[getwet2]

:06: I always used spit until I tried an antifog product, gold seal I believe it's called, it works way better than spit. I never thought about how it works, never really cared. I see from your profile that you are an Imagineer, so is this what you guys think about when you're staring through your mask at 60'? Maybe try some different dive sites that are more interesting! Just kidding, interesting question.

[scubasean]

:06: I always used spit until I tried an antifog product, gold seal I believe it's called, it works way better than spit. I never thought about how it works, never really cared. I see from your profile that you are an Imagineer, so is this what you guys think about when you're staring through your mask at 60'? Maybe try some different dive sites that are more interesting! Just kidding, interesting question.

Not sure how it can be "better than spit", at least in my case. Spit works quite nicely for me. I use it before every dive and never get fog. So, price is the only factor, and spit is free.

:banana:

[Scubakevdm]

Anti-fog works due to the priciples of molecular-tension and cohesive dynamics. Simply stated, the anti-fog molecules repel water molecules by giving them the finger and timing the punchlines of very funny jokes to cause them to shoot distinct streams of milk or soda from each nostril. This is why the worse your breath is, the better your spit works as defog. I have bottled mine, and am making it available for a modest fee. Please PM me with any requests.

[theskull]

Anti-fog works due to the priciples of molecular-tension and cohesive dynamics. Simply stated, the anti-fog molecules repel water molecules by giving them the finger and timing the punchlines of very funny jokes to cause them to shoot distinct streams of milk or soda from each nostril. This is why the worse your breath is, the better your spit works as defog. I have bottled mine, and am making it available for a modest fee. Please PM me with any requests.

Yes, I have a request. . . and for a modest fee I will reveal what it is.

theskull

[jimisurf]

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

[cancun mark]

90% of comercial defog is a tiny bottle of very expensive watered down dishwasher liquid.

Most of the time in the ocean spit works fine, but if you use suncream or (ladies) makeup, itputs a greasy layer on the inside of the glass, and you need the soap to break the surface tension.

I have one of those soap dispensers that you get in bathrooms on the side of my training pool, as there is always a layer of suncream on the top of any swimming pool, and I use regular anti bacterial liquid soap in it. It works great.

I did just have chance to use some comercial stuff recently though, and it seemed to be a little more like gel toothpaste mixed with soap. The mild abrasive helps.

The toothpaste trick for new masks breaks the surfactant layer used during the manufacturing process of the glass. When they make glass, they float it on top of molten metal to get it flat, but they need some kind of wax so it doesnt stick. This wax is why new masks fog up.

One other way to break in a new mask is with a cigarette lighter and burn this wax off, just be careful you dont burn the silicone skirt off too.

[crispos]

90% of comercial defog is a tiny bottle of very expensive watered down dishwasher liquid

Do you know that for a fact, cancunmark? You know, I was just looking at the bottles of Sea Drops (www.mcnett.com)
and thinking what a great business that is, selling them for $6 a pop. Great thread.

I would have thought it was glycerin, also used in K-Y jelly, which conjurs up alot of possibilities...

http://www.pioneerthinking.com/glycerin.html

As glycerin seems to be a by-product of soap manufacturing, you may be correct in substance. So indeed it is acting as a surfactant of sorts.

I think ChrisA probably has the mechanism of the fog formation right. It would seem to me that the warm breath of the diver hits the cold mask face. I don't think you need particles for that to create the condensation, although agreed the initial coating on the glass definitely enhances droplet formation. The glycerin dissolves the water molecules rather than allowing condensation.

At depth no more mask equalization occurs and the air in the mask gets colder and it stops fogging.

Probably the pool students continue to fog the mask because they keep taking it off at the surface to clear the fogging up, or they wash the glycerin off during the mask clears.

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

[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"

[ams511]

Ha ! Maybe we should try Rain-X. Works great on my truck, would hate to get it in the eyes though.

[Scubakevdm]

Another nice thing about baby shampoo is that in addition to being a good anti-fog, it also makes a great hair cleaning detergent for after the dive. I feel that it is worth noting that although spit may be substituded for baby shampoo as an anti-fogging agent, it should not be used as a hair cleaning detergent.

[H2Andy]

now you tell me...

[sgtmnstr]

I figure the reason a mask fogs up is that the inside of the lens is at a tempure below the dew point of the air inside the mask. So water
condenses on the inside of the lens. So how does de-fog (spit or
whatever) prevent this?

My first guess is that the stuff (spit, 500PSU, kelp juice....) afftects the water surface tension alowing the litle droplets to merge and form big droplets that roll of the lens, Or maybe it makes the lens less "sticky" so the condensed water rolls off.

I really don't even know why the condensed water on the inside of the lens stays in place Perhaps the antifog prevides a hydrophobic coating.

I could go on and propose many theories but maybe some one knows the answer. Started using baby shampoo and water mixed in a spray bottle, about half and half. Works like a charm and only cost about 2 cents a gallon. Picked it up from my instructor, spray a little in your boots also, keeps em smelling baby fresh.................

[rcohn]

Started using baby shampoo and water mixed in a spray bottle, about half and half. Works like a charm and only cost about 2 cents a gallon. Picked it up from my instructor, spray a little in your boots also, keeps em smelling baby fresh.................

Why are you guys making the effort of mixing it with water and carrying a larger bottle? You have all the water you'll ever possibly want at the dive site. Just put some baby shampoo in a small bottle, squeeze a few drops in the mask, add a little water when you rub it arund and rinse it out and you're all set.

Ralph

[H2Andy]

brilliant

[SamDiver14]

I love engineers.

[Laurence Stein DDS]

I hope I don't upset all those that replied...Defogs, either detergents, toothpastes, soaps, alcohols, or glycerine work not because they clean the mask (although they do clean the surface as well) but because, as a surfactant, they decrease surface tension. Drops or microdrops of water do not mound up as beads but, instead lay "flat" and their margins intersect forming a single sheet of water.

The surface of the glass in your mask may appear smooth and shiny but, in fact, it is pitted with microscopic depressions. Moisture is attracted to this uneven surface. Decreasing the surface tension and creating a moisture film prevents fogging.

Toothpaste is recommended for new silicone masks because microscopic particles of silicone...which repels water is impregnated onto the glass. The mild abrasive of the paste simply rubs away the silicone particulates. Toothpaste also has "foaming agents"...a long name for something a surfactant does. Therefore toothpaste can also be used as a defog in addition to its use as a glass cleaner.

Glycerine in actually a tri-alcohol. Alcohols mix with water and decrease surface tension. That is why you rinse your ears with alcohol...it breaks the surface tension of the water in your ear and allows it to be rinsed out. In addition, water goes into solution in alcohol forming an azeotrope. When you dump out the alcohol, you are also dumping dissolved water. This is also the reason that alcohol is used in fuel to remove moisture...the water dissolves in the alcohol and the mixture is then combusted and removed in the exhaust.

In addition, glycerine is not a biproduct of soap manufacture. Rather, it is instead capable of being turned into a soap. Neutrogena is glycerine soap.

Edit: Yikes...I made a mistake! Glycerine is a byproduct of soap manufactured from animal fat (tallow) and is capable of being saponified (turned to soap). Hey, I just want the facts!...Larry

So any compound capable of decreasing surface tension should be able to "defog" a mask.

Hope this makes sense. Everyone was sort of in the right track and with any luck I haven't made too big an ass of myself!

May your defog last as long as your dive.

[beachdivequeenbelam]

I hope I don't upset all those that replied...Defogs, either detergents, toothpastes, soaps, alcohols, or glycerine work not because they clean the mask (although they do clean the surface as well) but because, as a surfactant, they decrease surface tension. Drops or microdrops of water do not mound up as beads but, instead lay "flat" and their margins intersect forming a single sheet of water.

The surface of the glass in your mask may appear smooth and shiny but, in fact, it is pitted with microscopic depressions. Moisture is attracted to this uneven surface. Decreasing the surface tension and creating a moisture film prevents fogging.

Toothpaste is recommended for new silicone masks because microscopic particles of silicone...which repels water is impregnated onto the glass. The mild abrasive of the paste simply rubs away the silicone particulates. Toothpaste also has "foaming agents"...a long name for something a surfactant does. Therefore toothpaste can also be used as a defog in addition to its use as a glass cleaner.

Glycerine in actually a tri-alcohol. Alcohols mix with water and decrease surface tension. That is why you rinse your ears with alcohol...it breaks the surface tension of the water in your ear and allows it to be rinsed out. In addition, water goes into solution in alcohol forming an azeotrope. When you dump out the alcohol, you are also dumping dissolved water. This is also the reason that alcohol is used in fuel to remove moisture...the water dissolves in the alcohol and the mixture is then combusted and removed in the exhaust.

In addition, glycerine is not a biproduct of soap manufacture. Rather, it is instead capable of being turned into a soap. Neutrogena is glycerine soap.

So any compound capable of decreasing surface tension should be able to "defog" a mask.

Hope this makes sense. Everyone was sort of in the right track and with any luck I haven't made too big an ass of myself!

May your defog last as long as your dive.


THank you for your info. I like this kind of answer. It tells me exactly what I need to know and why. I am a WHY? person. I always want to know Why?

[Wijbrandus]

I used rain-x on my mask. It works really well on the outside (no water beads when I get back on the boat!) and keeps the fog down on the inside. I think everyone should try it. And the bottles are bigger than your usual defog, so you don't lose them easy, and you can still use it on your car. Awesome stuff.

I'm kidding of course. The stuff is great for the car, but I don't think it'll do the trick on my mask. Though it might do the trick on the skirt, as in destruction...

[Sideband]

I used rain-x on my mask. It works really well on the outside (no water beads when I get back on the boat!) and keeps the fog down on the inside. I think everyone should try it. And the bottles are bigger than your usual defog, so you don't lose them easy, and you can still use it on your car. Awesome stuff.

I'm kidding of course. The stuff is great for the car, but I don't think it'll do the trick on my mask. Though it might do the trick on the skirt, as in destruction...

When I'm done Rain-xing my mask, can I Armour-All the inside of my wetsuit to make it easier to put on? ;)

Joe

[O2BBubbleFree]

I carry a small 'travel size' tube of toothpaste in my mask box. For me, it works a lot better than spit. I've never tried shampoo, but I think I prefer the toothpaste just because you don't have to worry about it leaking when you change altitude (fly). 'Course, the shampoo won't leak if you remember to squeeze the air out.

Boycott shampoo. Insist on real poo. ;)

[H2Andy]

Boycott shampoo. Insist on real poo. ;)

:rofl:

[Curt Bowen]

Your spit globs to the glass making a biohazard bond that not even fog wants to touch!

[-=>Larry<=-]

Since this message string has come back to life a little - I was thinking [in a really idle & odd moment] about the Rain-x comment. It ought to work fine, but for the opposet reason that the surfactants are good - - It INCREASES surface tension to the point that no water can have enough contact area to stick to the mask.

It worked great on my car coming to San Marcos through some 1"/hour storms just now - but the lightning hit just in time to keep me from getting my dive in at Aquarena - thus I'm idly at the computer!

[Fivetide]

Yep got to agree De-Fog is expensive washing up liquid (watered down) I use fairy liquid (Washing up detergent( not u cheap Asda stuff)) and water on my Motorcycle helmet visor and it works a treat !! The only problem with spit is when you have a bit of a cold..and you get a bit of lung butter mixed in there without knowing it…. I remember once I did.. and followed what I thought was a large grouper for most of the dive that stayed always the same distance from me…should have guessed sooner it wasn’t, as I was in a Scottish Lake :)

[BradfordNC]

In addition, glycerine is not a biproduct of soap manufacture. Rather, it is instead capable of being turned into a soap. Neutrogena is glycerine soap.




yeah, did you pay attention during "Fight Club" ????

[BradfordNC]

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...


you must have missed the "war hammer" photo

[H2Andy]

yes i did, and diligent search of the archives still left me in the dark

[ScubaLoon]

To spit or not to spit, that is the question ;)

[H2Andy]

To spit or not to spit, that is the question


whether 'tis nobler in your mask to suffer
the slings and arrows of outrageous fog
or by expectorating end them

[BradfordNC]

yes i did, and diligent search of the archives still left me in the dark


they must have removed it from the board.

you might try a search for "deep relief"

just make sure you don't view when eating

[Laurence Stein DDS]

Since this message string has come back to life a little - I was thinking [in a really idle & odd moment] about the Rain-x comment. It ought to work fine, but for the opposet reason that the surfactants are good - - It INCREASES surface tension to the point that no water can have enough contact area to stick to the mask.

It worked great on my car coming to San Marcos through some 1"/hour storms just now - but the lightning hit just in time to keep me from getting my dive in at Aquarena - thus I'm idly at the computer!


Hi Larry,

Rain-X actually makes two products. One for the outside and a glass defogger for the interior of the car.

The INCREASED surface tension is great when the beads of water are subjected to the wind but I really don't think this is a good idea inside your mask.

On the otherhand, their glass defogger may be useful. It can be used on eyeglasses, interior auto glass, bathrooms, etc. I tried it in the shower and it only worked so-so. I'm gonna stick with spit...it's really cheap and if it doesn't work, it rinses out. I can't figure out how to get the Rain-X off...it just sort of has to wear off.

Regards

Larry

[Laurence Stein DDS]

To spit or not to spit, that is the question


whether 'tis nobler in your mask to suffer
the slings and arrows of outrageous fog
or by expectorating end them

Hey H2Andy...

Didga ever notice that drinking a regular (non diet) coke just before using spit as a defog makes it gooier and it seems to coat better :11: ?

I like to think of it as gourmet spit.

SPIT HAPPENS!!!

Larry

[BradfordNC]

Didga ever notice that drinking a regular (non diet) coke just before using spit as a defog makes it gooier and it seems to coat better :11: ?

I like to think of it as gourmet spit.



ummm, yeah, try it after eating a chocolate bar.

[Laurence Stein DDS]

ummm, yeah, try it after eating a chocolate bar.

With or without nuts? :06: