Under which conditions do photochromic lenses darken?

[ShadedChimera]

Just mere hours ago (6PM local time), I picked up a pair of Radarlock Path Photochromic Oakleys at a major department store here in Seoul. Given that Korea is in the Northern Hemisphere, there was still plenty of sunlight (though not near midday).

I hopped on a bus heading home and sat on the side that was getting most of the sunlight while wearing the pair. Initially the lens wouldn't darken, but I chalked that up to there being many apartments on the way home and the bus possibly having UV shielding on its windows.

When I got off at around 6:30, I stood in direct, unobstructed sunlight for about 3 minutes, but the lens still wouldn't darken. Today wasn't exactly a cloudless sunny day, if that's of any relevance.

So my question is, do photochromic lenses work best during the afternoon and become less dark for lack of a better term as the day progresses, or do I have a dud?

I'm going to wait until tomorrow lunch to try again and return it that day if need be.

 

[GavinL]

They should start to darken in less than a minute, I would take them back

 

[ShadedChimera]

They should start to darken in less than a minute, I would take them back

Bummer. So even past afternoon and before actual sunset, the lens should have darkened within a minute?

 

[Rustpot]

I wore a photochromic lens at work for safety glasses. I'd walk outside between buildings and even on a cloudy day the lens would have some tint to it.

It's UV activated, if the sun is out and it's not dark and stormy, there's UV getting through.

Now there IS a break-in period on the lenses. I think you're supposed to leave it out in the sun for 15 minutes to "activate" it. Or something like that.

 

[OakleyCan]

The lenses are activated by exposure to UV light. Not working on the bus is quiet normal as you are mostly shielded from the sun, hence why they are not popular for driving.

As for direct exposure, perhaps the sky was partially covered and a low UV day. I'd give them a proper chance before returning them.

 

[GavinL]

Bummer. So even past afternoon and before actual sunset, the lens should have darkened within a minute?

I would not say that that, my response was to your statement

I stood in direct, unobstructed sunlight for about 3 minutes

 

[ShadedChimera]

Thank you all for your replies.

I wore a photochromic lens at work for safety glasses. I'd walk outside between buildings and even on a cloudy day the lens would have some tint to it.

It's UV activated, if the sun is out and it's not dark and stormy, there's UV getting through.

Now there IS a break-in period on the lenses. I think you're supposed to leave it out in the sun for 15 minutes to "activate" it. Or something like that.

I'm going to have to spend at least ten minutes walking in broad daylight tomorrow moving from one building to another. I'll pay attention to tinting as I move.

The lenses are activated by exposure to UV light. Not working on the bus is quiet normal as you are mostly shielded from the sun, hence why they are not popular for driving.

As for direct exposure, perhaps the sky was partially covered and a low UV day. I'd give them a proper chance before returning them.

Tomorrow is supposed to be a cloudless sunny day. Let's hope for the best.

I would not say that that, my response was to your statement

I stood in direct, unobstructed sunlight for about 3 minutes

Right, but this was around 6:30PM-ish, and the sun wasn't as bright as when it was at noontime, hence my question about lesser tinting past noon.

 

[Peeza21]

One thing I've noticed with my photochromic RX lenses is that I don't notice that they've gone dark. The look through them stays exactly the same even when they've gone from 95% transmission to 18%

 

[Rustpot]

One thing I've noticed with my photochromic RX lenses is that I don't notice that they've gone dark. The look through them stays exactly the same even when they've gone from 95% transmission to 18%

Right, the gradual transition isn't very apparent when wearing them, until you take them off or walk inside.

 

[Dieseltech]

The Radars I have darken pretty fast but they dont get super dark.