Does anti-fog coating on glasses work?

February 2, 2021 7:51 AM

I am in the process of buying new glasses, and I have the option to add an anti-fog coating to them. If you have that on your glasses, does it work? And specifically does it work to prevent fogging outdoors when you where a mask? Are there any downsides to an anti-fog coating that I should be aware of?
posted by nanook to Shopping (12 answers total)

Response by poster: *wear* a mask.
posted by nanook at 7:52 AM on February 2, 2021

I would never go without this coating because it makes my glasses much less reflective (so more comfy to wear all day - the key benefit for me, and why it used to be called anti-reflective coating) and a bit less prone to grub (it's hydrophobic)...but it won't stop mask fog. The only downside is that sometimes it can flake if it's scratched through, but I've not seen that issue for quite a few years.

For mask fog I've been having some success pulling my mask up to just under my eyelids, and making sure there's space for air to travel sideways or preferably down from my mouth.
posted by london explorer girl at 8:14 AM on February 2, 2021 [1 favorite]

It works sort of - for the first year, then degrades. Much like transition coating, it wears off depending on how often and with what you clean your glasses with.

No other downsides that I have found in 20+ years of getting anti-fog coating.
posted by rozcakj at 8:14 AM on February 2, 2021 [2 favorites]

and making sure there's space for air to travel sideways or preferably down from my mouth

The "ear-loop-twist" works for me - but people here have been horrified that it makes gaps, so in theory droplets can get out. My theory is that they will hit the front of the mask when exhaling, and only air will escape out the gaps - I am not breathing sideways...

And - I did not know it used to be called anti-reflective/glare - which, for me is a must.
posted by rozcakj at 8:19 AM on February 2, 2021

No, coatings do not work - they're just a way optometrists upsell their products. And after a while, the coating wears away, sometimes flaking off in an ugly, inconsistent manner. Try to avoid (although they may be included, by default, whatever your request).
posted by Rash at 8:49 AM on February 2, 2021 [2 favorites]

(an appropriately sized [small] bandaid or a small strip of surgical tape [can buy at pharmacies' first aid section, the translucent 3M brand tears easily and cleanly] to adhere the top of your mask to your nose can help prevent fogging)
posted by porpoise at 9:17 AM on February 2, 2021 [1 favorite]

This article was in The Guardian yesterday and I just ordered some of the ProGear anti-fog gel which the writer recommends. I also find that twisting the ear loops makes a tighter fit, and in home-made masks where there's a pocket for a nose-wire (usually a bit of pipecleaner), I've replaced the more flexible nose wire with some of that soft foam-coated flexible garden wire (you want the soft one, not the more rigid one, often described as 'durable').
posted by essexjan at 9:42 AM on February 2, 2021 [1 favorite]

There are anti-fog cleaners you can buy, that clean and polish the lens. I don't know what effect they will have on coatings. I leaned about these when I used to scuba dive.
posted by tman99 at 10:36 AM on February 2, 2021

Soap residue makes a decent temporary anti-fog. Moisture still accumulates, but the soap breaks the surface tension so that you get a thin layer of water rather than lots of tiny droplets. I pour a couple drops of diluted (maybe 5%) Dawn dish detergent on my glasses, let them dry (or use a hairdryer if in a hurry), and then buff out the streaks with a cloth. Works for bathroom mirrors too.

Here is a legitimate source for headband-style masks which provide a good seal on my particular face while wearing glasses: https://bonafidemasks.com/kn95-respirator-mask-headband-style-fda-authorized/
posted by gray17 at 10:48 AM on February 2, 2021 [1 favorite]

My anti-fog coating has always worked for me, within reason. Yes, it degrades over time, but I've never had any real problems with that, either -- by the time it happens, I'm due for a new prescription, anyway.

That said, I have all the trimmings added when I go for a proper everyday pair of glasses -- anti-fog, anti-glare, anti-scratch, Zeiss lenses, all of that. I invest a fair bit to go top of the line for my glasses. I've also ordered cheapo online glasses as second pairs, and given the quality difference, I wouldn't expect much from those add ons (if I would bother at all). Point is, there's a price-quality index at play with this.
posted by Capt. Renault at 12:25 PM on February 2, 2021 [1 favorite]

I use cheap medical tape to create a seal across the top of my mask. Two strips - start at the bridge of the nose and follow the shape of the face left to avoid gaps, then do the right side. Don't tape up the entire top of the mask if your glasses are smaller, just enough so that air can't go directly up into the glasses. There will still be some slight, brief occasional fogging.

You'll have to leave the mask taped on the whole time you are out, and removing it involves scrunching up your eyes and peeling off the tape very slowly.
posted by BinaryApe at 12:30 AM on February 3, 2021 [1 favorite]

Not to be a downer, but I have tried just about every suggestion to avoid fogging up my glasses in the book, multiple masks (including a silicone one with a filter insert), anti-fog spray, diluted dish soap, masks with the metallic strip in the nose bridge part, etc. and have not yet found anything that worked flawlessly. The best results I've gotten are with double-sided tape strips but even then, it's uncomfortable to wear and you have to be absolutely sure to get no gaps between your mask and the tape, and it doesn't work well with all of the fabric masks I have (it probably works fine with paper-based disposable masks, tho, so that's a thought).
posted by Aleyn at 1:03 PM on February 3, 2021 [1 favorite]