Far from me getting in the way of good science, and I'm all for a good theoretical discussion when its too cold to dive outside, but for the average joe, this might get them too energized. Soon we'll be having new divers cleaning their masks with flamethrowers and chainsaws. I'm having Mythbusters flashbacks.
FWIW, I've used cerium oxide to buff scuffs out of dome ports. It works great, but it will strip the anti-reflective coatings for sure. It's way more than is needed.
Bringing it back to the practical, because it just isn't that hard:
1. What is important for anyone is a good fitting mask. Lots of divers bubble around the edges of their masks and don't even know it. The mask isn't flooding, they are just exhaling a little through their nose and it bubbles out the top of the mask. That leads to fogging - it is a constantly refreshed stream of warm humidified air. A better fitting mask that is a tad more resistant to leaking bubbles, combined with awareness by the diver not to breath out of their nose, will go a long way to limit the problem. If you're a persistent fogger, try a few mask off drills, getting comfortable breathing underwater without any mask and you may find that your fogging problem goes away as you get better at isolating your nose breathing from your mouth breathing.
2. A new mask is not that hard to clean. I've flamed, toothpasted, sea buffed and toothbrushed them -- and it all works. What seems to work BEST for me is to clean the entire mask, not just the lens, with a mild soapy something. Nothing harsh, but get the oily stuff off everything. Then go to work on the inside of the glass. As I said before, I've found a Sonicare toothbrush to be a great tool, but you can use a finger. It just takes longer. Don't skimp on the time. Get the whole inside with something mildly abrasive like whitening toothpaste or sea buff. You shouldn't need to flame, but you can if you want. Just be careful around the silicon and don't plunge the thing into cold water afterwards. But, this is a last resort for me and is no substitute for the other cleanins because you cannot safely flame the coating along the edges where the lens meets the silicon. With a electric tooth brush, the whole process takes 5 minutes. Done.
3. In terms of what works in the water to prevent or minimize fogging, for reasons I don't understand it seems to depend on the person, despite the fact that the physics ought to be the same for all of us. Spit, baby shampoo, sea gold, sea drops, etc. Whatever works best for you. Personally, for me sea gold works a little bit better than baby shampoo, but shampoo is fine 99% of the time.
4. Be careful about sunscreen, lotions, etc. All of that stuff will lead to fogging and if it's on your face, you can count on it migrating to your glass and then you're done. I generally sunscreen my face with something good at night and then just wear a hat on the boat, saving the sunscreen until after the dive - but, I have pretty sun-resistant skin. Just try to keep it away. Also, freshwater lakes that are alkaline, like many quarries, tend to strip away defog. A couple of flooding drills at our local training lake and it's fog city.
