coliseum once bubbled...
Just to share my experience with you... the best Defogger I have used (I have tried almost everythinG)... is JOHNSON BABY SHAMPOO...
This is no joke... try it and thank me later if you have not tried it before...
Jim Wyatt of Reefdivers used scented baby shampoo, bubblegum, I think it was, and it worked great.
I use SeaDrops, because I kinda collect them, they have individual diveshops names printed on the label, I always have several bottles on me.
I have used Fog-X, applied the night before diving and allowed to dry, and it's lasted for weeks.
Masks fog because the warm moist air you exhale is cooled by the outside water temperature cooling your mask glass.
This can be aggravated by exhaling partially through your nose, which many people do without knowing.
Using a wetting agent in the mask will relieve surface tension of the condensation, and no fog forms.
Just about anything will work to do that, the question is, how long it stays before being washed out.
If your mask leaks a ton, you'll wash out whatever you use, regardless.
If my spit was less soluable than a chemical agent, I might think about seeing a doctor...