lense coating repair diy
I recently purchased a used mask and the protective coating had areas where it became detached from the lense(air bubbles). As an experiment I dug into my bag of custom vinyl sticker experience and coated the entire lense with dish soap and let it sit for a day. After it sat I used a squeegee and pressed the coating back onto the lense. About the same idea as applying window tint. It's been about 2 months and it's still perfect.
My speculation with this mask is that the previous owner used high pressure water to clean which forced it's way between the lense and coating.
Hope someone finds this helpful.