I hike in the ice and snow of the New Hampshire White Mountains in the Winter and I hike in heat and humidity of same peaks in the Summer.
In Winter, my glasses and goggles fog as they accumulate moisture from my breath and the moist heat radiating from my body.
In the Summer, my glasses fog in the humidity of trails that follow streams and waterfalls.
What technology do I use to keep my glasses fog free in subzero winter hiking and the blistering heat of summer?
The answer is not entirely obvious.
How do anti-fog products work?
They are hydrophilic - water vapor accumulates on glass as a thin layer of water, preventing fog.
However, in the winter, the thin layer of water freezes solid, rendering glasses entirely opaque.
After trying many anti-fog products to keep my eyewear clear in winter, I finally figured out that hydrophilic anti-fog products cannot work in winter. What you need is a hydrophobic product - Rain-X Glass Treatment.
It prevents water from accumulating on glass and in the winter, works perfectly as an anti-fog treatment.
However, as temperatures rise above freezing, hydrophilic is the right answer. I tested several different anti-fog products on my bathroom mirror. The winner, creating the clearest glass with the thinest layer of water was Rain-X Anti Fog.
Thus, my technology to keep my glasses clear in outdoor pursuits is simple
Hydrophobic Rain-X Glass for winter
Hydrophilic Rain-X Anti-Fog for summer.
Clear vision based on science. That's cool.