Ratio of Johnsons baby shampoo and water for

[Lorenzoid]

Without diluting.

Two squirts, then I rub it all around and rinse it with sea water.

The key is to rinse it gently.

You need to leave the transparent film that the shampoo imparts.

The film is what creates a thermo barrier.

Is this statement correct as to what the mechanism is that provides the defogging effect? I know there have been a zillion threads on defogging, but it isn't clear to me exactly HOW it works.

I have tried diluted baby shampoo in a wide range of ratios. I have tried using a (scrupulously clean) toothbrush to spread it around. Diluted baby shampoo does not work well for me. The only method that seems to work consistently for me is rubbing (with clean fingers) a few drops of undiluted baby shampoo (or commercial defog), then rinsing gently a couple of times.

 

[bradymsu]

My buddy is a homeopath and he uses a ratio of 1:20,000. Although you may want to avoid J&J due to the potential of blood clots. Disclaimer: I am not a doctor.

 

[Lorenzoid]

My buddy is a homeopath and he uses a ratio of 1:20,000. Although you may want to avoid J&J due to the potential of blood clots. Disclaimer: I am not a doctor.

But the advantage is you only need one dose/application, and it doesn't have to be stored in liquid nitrogen. Wait, are we talking defog?

On the topic of Johnson's Baby Shampoo, I am disappointed to find it is no longer tinted yellow; rather, it now is clear but sold in a yellow-tinted bottle. I like to buy a large bottle to use to fill refillable smaller bottles for dive buddies and me to stash among our gear. There is some potential for confusion with a bunch of small bottles with clear liquids, some of which may be defog, others of which may be ear beer, etc.

 

[tridacna]

Is this statement correct as to what the mechanism is that provides the defogging effect? I know there have been a zillion threads on defogging, but it isn't clear to me exactly HOW it works.

Glass has micro-cavities. Fill them up with an aquaphobic substance before water vapor does. Voila.

 

[hedonist222]

Is this statement correct as to what the mechanism is that provides the defogging effect? I know there have been a zillion threads on defogging, but it isn't clear to me exactly HOW it works.

I have tried diluted baby shampoo in a wide range of ratios. I have tried using a (scrupulously clean) toothbrush to spread it around. Diluted baby shampoo does not work well for me. The only method that seems to work consistently for me is rubbing (with clean fingers) a few drops of undiluted baby shampoo (or commercial defog), then rinsing gently a couple of times.

I'm fairly certain thats how it works.

To test it - squirt some undiluted shampoo, then rub like you normally would.
Then wash it out really well. As in scrub the lens as hard as you can. Then breathe into the mask. It'll fog up.

I'm not a chemist but I figured out that the thin layer you leave behind by gently scrubbing acts as a thermo barrier between the cold outside and the warm inside.
A thermo buffer zone.

This would not work with dish detergent - because by virtue of what it does - the dish detergent cleans the surface by breaking down oils and leaving it squeaky clean - but not thin layer left.

 

[Lorenzoid]

Glass has micro-cavities. Fill them up with an aquaphobic substance before water vapor does. Voila.

Aha. So there IS some minimum amount or viscosity or whatever needed; too dilute a solution and it will not work. And you can't go wrong with 100%; the only reasons to dilute it with water might be to make it more economical and easier to apply (by spray, for example)? Is my logic correct?

 

[lexvil]

The only problem with 100% is that it’s so thick it can impair vision as much as fog, unless heavily rinsed, diluted it will sheet faster with less residual.

 

[Lorenzoid]

The only problem with 100% is that it’s so thick it can impair vision as much as fog, unless heavily rinsed, diluted it will sheet faster with less residual.

Good point. As I said above, I like to use 100%. But unless I spread it very evenly and thinly, rinsing often results in some spots being over-rinsed and others under-rinsed.

 

[hedonist222]

Good point. As I said above, I like to use 100%. But unless I spread it very evenly and thinly, rinsing often results in some spots being over-rinsed and others under-rinsed.

squirt two blobs on each side

use your finger to glide the shampoo all over the lens

go over the whole surface twice

then scoop in some sea water and gentle swish away the shampoo with you finger

don't press into the glass otherwise you're just removing the film

swish away the blob of shampoo

until it looks clear

 

[tridacna]

Nothing to do with “thin layers” or “film” left on mask. Either it fills the microcavities or it doesn’t. Viscosity seems less important than the chemistry. If 100% works for you - great. I only use 20% - works for me.