FogCity is part of the Pinlock group, which produces specially formulated self-adhesive visor inserts for the military, emergency services and bikers. It now produces the same material in a version cut for dive-mask applications, and sent me some to try out.

The Design
The plastics used in the FogCity inserts have a chemical formula that absorbs the moisture, keeping its surface free from condensation. The inserts are adhesive on one side and simply stick to the glass surface inside the mask. One corner section is adhesive-free to aid removal.
The inserts are available for both twin- and single-lens masks, with two sizes to cover most of the popular mask models. They have a limited lifespan, however, and will need to be changed after 20 or so dives, because as they absorb moisture the chemicals are depleted. The lifespan is shortened further if the inserts are used in chlorinated swimming pools.

In Use
The inserts were a doddle to apply – all I had to do was stick them on to the inside of the mask lenses. The glass surfaces needed to be clean and free from detritus, and I found that I had to apply pressure with a finger from the centre of the insert to squeeze out any trapped air, but once done they stayed in place.
Under water they worked like a charm. I had deliberately taken a new mask with me, one that hadn’t had the silicon release agent removed with an hour or so of scrubbing with toothpaste.
There was the added advantage that I didn’t need to apply any defogging fluid (spit) or use any propriety agents such as baby shampoo or Mask Clear to keep the lenses fog-free.
Between dives I could also avoid having to place them in that bucket of diluted snot and sunscreen that’s always found at the back of a dive-boat.
Under water they stayed clear, giving me unrestricted vision when looking for critters to photograph and, more importantly, when assimilating the complex information displayed on my computer screen.
I used the inserts for a full week of intensive diving in Egypt’s Red Sea, and they performed as well on the last dive as they had on the first.

I’ve been testing masks for these pages like a man possessed for more than two years now, with each one going through the toothpaste routine and having propriety agents applied before each dive to stop it fogging.
I sometimes take two masks on each dive, swapping them over under water, and this invariably results in the second mask becoming completely misted up, because any anti-fog treatment has been washed away long before I put it on.
These inserts would have saved me a pile of trouble and anxiety in these circumstances, and it’s where I’d use them mostly.
I think the limited lifespan is a drawback, but they should last for a full diving holiday or liveaboard trip, and you can put your mask back in its protective box between dives instead of a germy bucket or, worse still, the dedicated rinse-tank for my camera housing.
The alternative is to rub the prints off your index fingers with vigorously applied bi-carb of soda toothpaste as you polish the mask lenses into a shine. This is very cheap, and will help to stop that condensation appearing indefinitely.

PRICE: £11 (two sets of inserts)
VARIANTS: Twin-lens, single-lens

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