Hot take: a $9 can of silicone spray fixed my mask fog and I'm mad I waited 6 years
I dive mostly shallow intake work around Chattanooga and my mask fogged every single time once I hit about 20 feet, no matter what defog goop I smeared on it. Last month a tender handed me a plain can of silicone spray, the kind you'd use on a stuck window, and told me to try it on the glass instead. One light coat, let it sit, no rinse, and I got a full 90 minute shift with zero fog, three days straight. I almost told him to keep his hardware store junk to himself, and I'm glad I didn't. What I learned is that half my fog problem was me scrubbing the lens with my fingers and leaving oil behind, not the defog. Anyone else quit the fancy defog bottles for something from the paint aisle, and did it hold up on a longer decompression job?