Do professional chefs and bakers need glass eyeglass lenses?
June 8, 2024 9:04 PM   Subscribe

I understand that various coatings on plastic and polycarbonate eyeglass lenses don’t hold up in high heat environments. Is an uncoated non-glass lens prone to damage or deformation after prolonged exposure to the high temperatures of a professional kitchen, bakery or barbecue?

When I started wearing glasses last year, the optometrist told me that I should be careful to remove my glasses before bathing at an onsen (hot spring bath) because the heat might warp the lenses.

At first I wondered if it wasn’t simply standard Japanese oversolicitous customer service, but when I looked it up, I found that the various anti-glare etc. coatings on the lenses are not particularly heat proof.

Most of the data I can find about durability differences between the lenses themselves is naturally more focused on impact and scratch resistance.

What I want to find out is whether the lens itself would warp in a sauna or other hot room, and if that is the case, do pro chefs, bakers and pit masters require glass lenses in their eyeglasses?
posted by Ice Cream Socialist to Work & Money (7 answers total)
Response by poster: I swear I wrote “optician” not “optometrist.” I blame these dang eyeglasses.
posted by Ice Cream Socialist at 9:07 PM on June 8

Best answer: The glass transition temperature for polycarbonate is 145C (~300 degrees in Freedom units). Any temp where you aren't experiencing burns should be OK.

Anecdotally I've left many a pair of plastic safety glasses (which are almost universally polycarbonate) on the dash of a vehicle in full sun when temperatures have been in the high 30s (interior temps easily 50C) with no observed ill effects.
posted by Mitheral at 9:42 PM on June 8 [1 favorite]

Best answer: I learned the hard way that saunas are hard on lens coatings. I did not notice any other structural changes to the lenses or metal eyeglass frames. I suspect that I didn’t notice these changes because it wasn’t that hot for that long relatively speaking.

There are some sources out there that advise not to leave glasses in a hot car. At the same time, this doesn’t seem to be a common enough occurrence for people to stop leaving glasses in their car.

My non scientific explanation is that the coatings are the most heat sensitive part of the glasses, and can be affected by heat in conditions tolerated by humans. The heat required to warp a frame /lens would be at a temperature that is also dangerous for humans.
posted by oceano at 9:57 PM on June 8

My coated lenses got damaged from being exposed to being in the direct sun for too long (while I wasn't wearing them). The coating developed a strange wrinkled texture similar to frost patterns. They're glass lenses, it was the coating that was affected.
posted by Zumbador at 12:19 AM on June 9

My eyeglass frames are acetate, and to bend the earpieces to fit my ears the optician simply heated them up in a sort of tubular hair-dryer device and bent them with her hands. I could imagine that the frames could get deformed in a human-tolerably-hot environment like a sauna.
posted by heatherlogan at 4:41 AM on June 9

Best answer: My experience: I wear magnifying glasses, nothing fancy, to read fine print/phone/screens; I also occasionally wear makeup.
When you open an oven that's been turned on full blast 450-550 (a basic loboy, not a pizza deck) the heat is immediate; I could feel my glasses frames getting warm right away. If I wasn't wearing glasses at the time and reached in, there were times I could feel my makeup, specifically mascara, melting away. It didn't run down my face but it was gone baby gone. So it's a lot of heat very quickly. One learns to lean back when opening that oven, until the first rush of very hot air is out. Same if grilling with a closed (outdoor) grill-- they can get very hot when the lid is on.
posted by winesong at 5:19 AM on June 9 [1 favorite]

> I learned the hard way that saunas are hard on lens coatings.

Same. I had to get the lenses replaced, but only because the coating had distorted. The lenses themselves were fine as were the frames. An expensive lesson!
posted by gingerbeer at 2:23 PM on June 9

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