EK USA FAQ
What is Cat Crap?
An anti-fog paste from EK USA. Skiers have used it for decades; it works just as well on glasses that fog when you walk in from the cold. Sold as a tin of paste, a spray, and single-use packets.
How do I use it?
A thin smear on both sides of a clean, dry lens, let it haze, then buff clear with a soft cloth. It lasts a few days of use before you reapply. One tin gets most people through a winter.
Will it hurt my anti-reflective coating?
It's made for optical lenses. The only way to damage a coating is buffing with a gritty cloth, so use microfiber.