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Comment by andrelaszlo | Hacker News Reader

I asked the optician how they clean glasses:

- Wash with cold water. Warm or hot water might ruin the coating. (Our water comes supercooled right out of the tap in the winter,so in order to not have my hands instantly frozen into a solid block of ice I go for 15—20 degrees or so.)

- Use a drop of mild dish soap without ammonia.

- Dry them with a soft clean cloth (they use microfiber I think, I just use a random soft towel that doesn't give off any lint/dust)

Doesn't have to be more complicated than that. It takes 20 seconds and my glasses are as good as new.

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My opticians have always given me a microfiber whenever I got a set of glasses made, and last time I went I asked for a spare as well. Now I have the habit of having one in my pocket at all times so I don't have to devolve back to using the bottom of my tshirt.

I ordered a pack of 100 off amazon, and I have them everywhere -- desk, laptop back, suitcase, car, bookshelf, etc...

Realistically, I wash my t-shirt much more often than any microfiber cloth...

Yeah, but the fabric of my shirt seemed noticeably worse at cleaning my glasses, so I stopped using that completely. Having a microfiber on hand at all times is very helpful for that

Wash with cold water. Warm or hot water might ruin the coating.

This is why I worry about radiant heat from fires while camping or burning yard debris. Plastic lenses are usually opaque to IR and that means they're heating up even more than you might think.

I once ruined the coating of my glasses by sticking my head into a hot oven to check a disk I was baking. The surface of the lens sort of blistered. From then on I removed my glasses when checking on food in the oven... I also try not to stick my head so far in also.

Chef tip: Take the item out of the oven instead of inserting your head into the oven.

Hanzel and Gretel hate this one simple trick!

Glasses are plastic lenses? I thought they were… glass. Am I wrong? Warby Parker and such are plastic?

They used to be actually glass, but now the majority are plastic.

For people with poor eyesight (like me!) plastic lenses are lighter and can have a higher refractive index, making them thinner than the equivalent glass lenses. Weight is the big thing though.

Another reason to consider glass lenses.

Unless they're completely plain lenses the heat could still ruin the oleophobic and anti-reflective coatings.

Can you even get glass lenses anymore? I don’t recall seeing it as an option the last time I ordered a pair but maybe since Zenni tends to focus on affordability they don’t bother offering the (presumably more expensive) option.

Yes https://lensfactory.com/ They are so much better.

Heh, its funny, whenever I see a video of an American with glasses, they don't have a reflective coating. I guess its too expensive over there. I have glasses which have reflective coating and photochromic coating. They're also made of titanium. Very light, despite being -4 or so. My wife has even worse than -4, and she enjoys the same. They're a tad more expensive, yes, and eventually the coating goes bad which with proper usage can be postponed for years (e.g. wear real sunglasses on beach).

Do they shatter when you drop them?

They might if you drop them hard enough, but I've dropped glass lenses numerous times and I've never had them shatter on me. Probably helps to have a sturdy frame with barrel hinges, too: https://shop.shuron.com/shop/sidewinder/

I asked my optician to please give me glass lenses and avoid the shenanigans with inferior materials, but they declined citing safety concerns with broken glass. Ah well.

There's absolutely nothing unsafe about glass lenses if you're a normal person and don't abuse them. They're actually superior to plastic in terms of longevity and durability. What I've found is that the tradeoff is durability vs. weight. Glass is heavier than plastic but if your glasses are well-fitted and adjusted, this is not a problem. Also, in terms of cleaning you can be a lot less careful with glass and they won't scratch. I had a pair of glasses with plastic lenses and my wife tried to "help" me by cleaning them with a paper towel when I wasn't around. The lenses got scratched up and unusable. Never again...it's glass lenses in Shuron frames for me!

I would rephrase that as: There's nothing dangerous about them until an accident happens. And that's why it's not worth it to me. I saw my dad's eye surgery from a glass-lenses incident years ago - he was lucky, it still was an awful experience. Should he have been wearing a pair of goggles while working in the yard? Sure. But I've forgotten that too!

Most eye 'glasses' are eye plastics. Plastic lenses are softer than cellulose = kleenex scratches them. There is no easy way to avoid scratching plastic apart from detergent rinsing and soft lens cloth pat drying. I buy true glass lenses, hardened so they break into splinters (I have never broken one) To clean, I wash with warm water and dish soap = they last for years and I need new ones due to eye aging before they ever get scratchy. A few others made this point as well.

I have glass lenses, but I don't care to find out what happens if ever an airbag explodes into my face.

Fun fact: if you're ever institutionalized for suicide watch, they confiscate your spectacles due to a perceived risk of being able to break them and cut yourself, even if your spectacles aren't made of glass.

Glass lenses are only good for spherical prescriptions. If you have astigmatism, you need an aspherical lens, which cannot be shaped in glass.

Anyone who is into photography knows this is flat-out untrue. Aspherical lenses are a big deal in the high-end camera lens world. Canon, Nikon, Leica, Zeiss, etc. all have aspherical lenses.

I wear glasses and my glass lenses are made by Zeiss. My left eye has mild astigmatism and the glasses correct it perfectly. Each one is made from a single piece of glass that is ground to shape.

Thats not true, I have glass aspherical lens.

That you wear for prescription glasses? Unlikely. Glass cannot be shaped into aspheres without very expensive grinding and polishing techniques. Multiple glass shapes are typically molded together to make an aspheric lens. The challenge is that molding the lens this way decreases the Abbe number significantly, which is why it’s not used for prescription eye glasses. If you have astigmatism, your lenses are most likely a polymer of some sort. Check with your optometrist.

I know exactly what I have. You can even get glass progressive lenses which are very aspherical. https://lensfactory.com/collections/progressive/products/pro...

I've owned several pairs of aspherical lenses made of glass, ground by competent yet hardly exceptional shops. Only in the U.S. I found people uninterested in selling me glass lenses--exaggerated mimicry, "but they'll be so heavy!", etc.

> "but they'll be so heavy!"

Yeah, they are. If you only have say -2 its no big deal. I have -4 and with heavy glasses (I used to wear such) I get pain in top of my nose rather quickly.

Are optical coatings that sensitive that warm water might bother them? I'll have to treat my lenses differently.

The anti-reflective coating expands and contracts differently with heat than the plastic lens underneath. A big temperature difference will cause it to crack. So don't use ice cold water, use water that's at room temperature, which is usually what comes out of your cold tap.

> water that's at room temperature, which is usually what comes out of your cold tap.

Is that really your experience where you live? In mine, the cold tap is cold - once allowed to run through whatever's in the pipes in the building, since it's come from underground.

It depends on where you live and the time of year.

I've lived places where in the winter, the tap water is just a couple of degrees above freezing. I've lived in places where in the summer I've measured the tap water at over 90 degrees.

He must live somewhere that doesn't get to any real temperature extremes.

Yeah, I used to wash my glasses in hot water. I didn't notice an instant change, but it noticably degraded their quality after a while. Water straight from your cold tap is the way to go.

I've ruined my coatings by wearing them in the sauna before. Sauna temps tend to be around 180.

> Our water comes supercooled right out of the tap in the winter

I'm from a place that never really gets below freezing, so I have to ask. Is this serious? If so, that's fascinating. When you turn the tap on, does the water instantly turn to slush on the way out? Does it come out at full speed or sluggishly?

It is serious but in hyperbole. The water is probably near freezing, but not below. Frozen pipes are a big problem in cold regions, they expand and burst, so measures are taken to insulate and keep the pipes warm. Depending on the piping though, sometimes the only resort is to completely drain the pipes during winter and not have any running water for that part of the year. (Common in cottages rather than real homes)

I believe they were exaggerating a bit. Water pipes are typically buried deep enough in the ground that the water gets very cold but not frozen. The pressure in water lines isn't high enough to really drop the freezing point of the water to an appreciable amount.

Groundwater tends to be around the local air temperature averaged across the whole year. It is considerably colder in northern climates.

Not literally supercooled though, pipes aren’t that pristine, they will happily freeze.

I use a tall glass with tap water and some dish soap. Dunk them in while I shower, then remove, rinse off with cold water. Afterwards I could use a towel, but actually I tap them dry with a sheet of toilet paper. I THOUGHT that would leave small dust, but surprisingly, does not.

I use cheap, uncoated glasses though and replace them every 3-4 years anyways.

I second this. Super easy to do and kept my current 1 year old glasses in great shape.

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