Actually during Special Operations Warfare training it's taught to pilots & other soldiers who have to wear a helmet/mask to use "HUMAN PEE, note only HUMAN pee will work" on the inside of their mask. This creates a great seal and does not allow the lens to fog up.
This has been well proven during combat operations that human pee works great to stop the fog on pilot lenses as well as other types of lenses used by the military. Experiments with dog, cat, and horse pee didn't work so remember to pee on your own lens before you take off guys.
Next time try PEE and then let us all know how it turns out.
Actually just joking,,, hopefully no one believed me!!!!