Mask fogging.

[Mopar]

My wife had the same problem with her mask, and we had to use toothpaste on it four or five times before it finally worked. You have to really rub hard.

I think they must not put as much abrasive in toothpaste as they used to - many years ago I remember polishing out the scratches on my watch crystal with toothpaste, but I don't think you can do that anymore.

It might be easier with auto rubbing compound, if you have a can of that around. Try it out on a window first to make sure it doesn't frost the glass.

I agree. But Colgate is stil pretty abrasive

Toothpaste before every dive.

Never fogs, but always raises cries of indignation from the internet.

I carry a sample or travel size tube with me in my mask box with my Sea Gold.

 

[Marek K]

Yes, the curing of the silicone has some ugly off gassing effects.

But that doesn't explain why replacement corrective lenses also need to be scrubbed to prevent fogging.

Things may have changed over the years but another source of the film is the way the glass is floated during manufacturing.

That might explain it, if I knew what glass floating was. But then I found this by the Triptar Lens Company, here:

During the 1950’s, Pilkington Glass of the UK developed a continuous melting and forming process for the architectural window markets. This kind of glass is called “float glass”. Pilkington’s float glass is melted and floated on a molten pool of tin. Gravity flattens the layer of liquid glass into a thin ribbon of very consistent thickness.

Is that what you're talking about? I had no idea. But is that how glass for corrective lenses is made too? Seems like it wouldn't, because of the thickness nad precision; Triptar is contrasting greenish "float" glass with their own precision lens glass manufactured in crucibles...