fatpossum is right. We make FogTech. And I feel for you riding in those low temps. FogTech is made for people who must have clear vision for their sport or at work. It is not meant for your bathroom mirror...it works but it is too expensive. It was developed specifically for plastic or coated lenses which all too often reject other anti-fogs.
Some guys at British Petroleum have tested FogTech on goggles down to -35 F with good enough results that they have bought 4,000 packets so far. I personally tested it on several sets of goggles, a motorcycle helmet and sunglasses in a blast freezer at -20 F with no fogging. I had to stop after my boots froze to the floor and I walked out of them.
But everyone's equipment is different, your weather is different and you sweat and breathe differently than your buddy. That's why his fogging solution may not work for you. I can spit on my diving mask and never have fogging problems. My wife needs FogTech. (She refuses to let me spit in her mask, silly girl.)
If anyone wants to test FogTech on your specific equipment, shoot me an email with your shipping address and I will send you two packets, no charge. Once you cycle with it, email me with what you used it on, what the conditions were like and if it cleared your fogging and how long it lasted and post those results here if that's OK with the moderators.
gene@motosolutions.com