In addition to cleaning off that stuff from the manufacturer with toothpaste, I've tried and tested quite a few things. 1st I tried that 500psi mask defoger stuff. I think it's pretty worthless. Without boring you with the details, let it be said that I've experimented a bit with this and here is the best 2 options.
1. Buy some Johnson & Johnson "no tears" baby shampoo, mix it 50/50 with water in a spray bottle, apply it to your mask, and don't rinse it all out. Your dive will smell like a baby, but it will be clear!
2. This one is the best! go to
www.fog-not.com and buy their solution. This is oderless and just works great! The have a terrible website, but the product rocks!
I promise if you do either one of these, you will not have mask fogging issues ever again..... period.