During the manufacturing of a mask, silicone vapor
deposits on the glass, which ensures that the mask
doesn't stick in the machinery. However, when you wear
it, humidity within the mask may cause it to fog. You can
usually prevent this by scrubbing off the silicone film
with old-fashioned white toothpaste (not a gel) before
using your mask the first time. If you spread a pea-sized
lump over the inside of the glass and rub furiously, the
toothpaste will remove the deposit. Better yet, leave the
toothpaste on overnight and when you rub it off, it takes
the silicone vapor deposit with it. If that fails, one of our
long-time correspondents, Ken Kurtis, owner of Reef
Seekers in Beverley Hills CA, offers a solution (but keep
in mind that incautious use of a flame can weaken the
toughened glass and even damage the silicone skirt of
the mask).
"I decided to replace my old, well-used Atomic
Frameless mask with a new Atomic Frameless mask. As
you know, new masks have a coating inside from the
manufacturing process, and you need to scrub them
with toothpaste, Soft Scrub or something like that to get
rid of the coating. If you don't, then the mask will fog,
even when coated liberally with a defogging solution or
spit. I didn't do a good job with my new mask because it
fogged up fairly good on my test dive. But when I came
out of the water and relayed my issue, Nautilus divemaster
Dave Valencia said, "Why don't we burn it?"
"What he does is take a lighter and let the flame lick
the inside of the mask glass. He goes over every inch,
being careful not to get too close to or linger too long
near the skirt, lest you melt that. But when he was done
(it took maybe three minutes), the inside of my mask
was brown from the soot of everything that had been
burned off. I rinsed the mask thoroughly, dried it out,
reapplied McNett Sea Drops defog and . . . Voila! The
mask no longer fogged. It was truly amazing. A fireplace
lighter or BBQ charcoal starter, where you can squeeze
a trigger and get a continuous flame, may work the best
and avoid burning your fingers."