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 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.
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.
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.
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.
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?
Not literally supercooled though, pipes aren’t that pristine, they will happily freeze.
I use cheap, uncoated glasses though and replace them every 3-4 years anyways.
- 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.