Results 1 to 12 of 12

Thread: Tainted Tint

  1. #1
    Platinum Lounger
    Join Date
    Feb 2002
    Location
    A Magic Forest in Deepest, Darkest Kent
    Posts
    5,681
    Thanks
    0
    Thanked 1 Time in 1 Post

    Tainted Tint

    I read this in an article recently and thought it could be a nice little conundrum. <img src=/S/cool.gif border=0 alt=cool width=15 height=15>


    "I have a photochromic coating on my glasses. Under a blazing Caribbean sun they were only moderately tinted. However, under a weak midwinter sun in the UK they go almost black. Why?"
    Jerry

  2. #2
    WS Lounge VIP sdckapr's Avatar
    Join Date
    Jul 2002
    Location
    Pittsburgh, Pennsylvania, USA
    Posts
    11,225
    Thanks
    14
    Thanked 342 Times in 335 Posts

    Re: Tainted Tint

    I can see 2 possible answers, 1 seems more logical, but 2 may also play a role.

    1) <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold"> Midwinter sun is more indirect to the ground, so will be more direct to the glasses. Caribbean sun should be more overhead and less direct on lenses.</span hide>

    2)<span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">Temperature effect. I think I recall, though do not remember for sure, that they get darker when colder and less dark when hot. I think it has to do with the a slow down in the reverse reaction. The darkening is not affected by heat, but the reverse reaction is.</span hide>

    Steve

  3. #3
    Platinum Lounger
    Join Date
    Feb 2002
    Location
    A Magic Forest in Deepest, Darkest Kent
    Posts
    5,681
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: Tainted Tint

    I had a feeling you were going to be the first to answer and I wonder if you read the same magazine as I do.

    Both of your answers came back as possibilities for the reason as it is not necessarily the quantity of UV that causes the problem. The general feel of the responses are below:

    <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">
    1) Photochromic lenses are sensitive to temperature
    2) Particles of silver halide are trapped inside the glass and are transparent but when struck by UV they disassociate into halogen and metallic silver. The recombination reaction increases as temperature rises. Therefore you need more UV in a hot climate to get a darker lens

    </span hide>

    I could go on but the answers from readers is generally around the same matter
    Jerry

  4. #4
    WS Lounge VIP sdckapr's Avatar
    Join Date
    Jul 2002
    Location
    Pittsburgh, Pennsylvania, USA
    Posts
    11,225
    Thanks
    14
    Thanked 342 Times in 335 Posts

    Re: Tainted Tint

    I did not get this from a magazine, but I admit, to hearing about it before and it being discussed at work.

    Steve

  5. #5
    Platinum Lounger
    Join Date
    Feb 2002
    Location
    A Magic Forest in Deepest, Darkest Kent
    Posts
    5,681
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: Tainted Tint

    It was in New Scientist recently so I hazarded a guess that you may have seen it in passing...funnily enough this is the kind of topic point that gets brought up in our office that can be quite explosive with differing views <img src=/S/flee.gif border=0 alt=flee width=25 height=25>, quite fun, hence why I thought I would post it here <img src=/S/evilgrin.gif border=0 alt=evilgrin width=15 height=15>
    Jerry

  6. #6
    WS Lounge VIP sdckapr's Avatar
    Join Date
    Jul 2002
    Location
    Pittsburgh, Pennsylvania, USA
    Posts
    11,225
    Thanks
    14
    Thanked 342 Times in 335 Posts

    Re: Tainted Tint

    Yes these "academic questions" can get explosive.

    They are almost as explosive as topics about which Star Trek TV series (or even which captain) is the best or which manifestation of "The Doctor" you would most likely travel around with in the TARDIS...

    Steve

  7. #7
    Silver Lounger
    Join Date
    Mar 2001
    Location
    Dallas, Texas, USA
    Posts
    1,680
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: Tainted Tint

    I'm no scientist, but...
    Best Captain = Kirk [had a sense of humor]
    Doctor = Crusher [I have my reasons...]

    <img src=/S/2cents.gif border=0 alt=2cents width=15 height=15>
    - Ricky

  8. #8
    WS Lounge VIP sdckapr's Avatar
    Join Date
    Jul 2002
    Location
    Pittsburgh, Pennsylvania, USA
    Posts
    11,225
    Thanks
    14
    Thanked 342 Times in 335 Posts

    Re: Tainted Tint

    I didn't put them for debate, but I prefer Picard and "The Next generation" as a series.

    "The Doctor" I referred to was not in reference to Star Trek but to the British Series Doctor Who (A Brief History Of Time (Travel): Doctor Who On Television). The TARDIS (Time And Relative Dimension In Space) is his time travel ship that looks on the outside like a police call box and is much much larger on the inside (it is in other dimensions).

    Steve

  9. #9
    3 Star Lounger
    Join Date
    Aug 2004
    Location
    Saco, Maine, USA
    Posts
    293
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Tainted Tint

    1. The original series
    2. I'd boot out the Doctor, and would travel with Romana. She, at least, knew how to fix the Chameleon circuit!

  10. #10
    Platinum Lounger
    Join Date
    Nov 2001
    Location
    Melbourne, Victoria, Australia
    Posts
    5,016
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Tainted Tint

    I was going to suggest that the difference in observed tints <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">may be largely based in perception. There is much more light around everywhere in the first climate than the second. So a judgement of the apparent tint will be a reflection <img src=/S/pun.gif border=0 alt=pun width=22 height=18> of how much ambient light is transmitted through the lenses - lots in the Caribbean; little in the UK winter.</span hide>

    Alan

  11. #11
    Platinum Lounger
    Join Date
    Feb 2002
    Location
    A Magic Forest in Deepest, Darkest Kent
    Posts
    5,681
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: Tainted Tint

    Sadly not what the scientists said but still may have validity. Apparently there is a distinct difference from near Black in winter time and very light in the Caribbean.
    Jerry

  12. #12
    WS Lounge VIP sdckapr's Avatar
    Join Date
    Jul 2002
    Location
    Pittsburgh, Pennsylvania, USA
    Posts
    11,225
    Thanks
    14
    Thanked 342 Times in 335 Posts

    Re: Tainted Tint

    An excellent observation.

    <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">In a way this is like a tinted windshield. The window is the same "darkness" on both sides, but to the people outside of the car with little light coming out of the car, the window looks black. From inside the car, with a lot of light coming in, it can be seen through and does not look that dark (dark but not black).</span hide>

    Steve

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •