Polish plastic lenses

Discussion in 'Optometry Archives' started by _jk_, Mar 6, 2006.

  1. _jk_

    _jk_ Guest

    Is there any way to polish the surface of plastic lenses? They're
    just slightly abraded, so even if they can't be machine polished,
    maybe there is a liquid coating that would fill in the light
    scratches?
     
    _jk_, Mar 6, 2006
    #1
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  2. _jk_

    _jk_ Guest

    Not to interrupt all the interesting conversations here (is this
    really a sci.med group? What happened?) but I have an easy question:
     
    _jk_, Mar 7, 2006
    #2
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  3. _jk_

    drfrank21 Guest

    There isn't any product that will do the job (I know
    there are some commercial products but they
    do not work). Trying to polish the lenses will
    mar the optics. Bottom line- new lenses.

    frank
     
    drfrank21, Mar 7, 2006
    #3
  4. a liquid coating that would fill in the light scratches?

    I think that the reason a liquid coating would not work is that it
    would have to have _exactly_ the same index of refraction as the glass.

    I once saw a neat experiment - a guy took an empty drinking glass and
    put it in a big transparent container full of water. You could easily
    see the facets of the glass in the water, because the water and the
    glass refracted light differently.

    He then took another glass and put it in some kind of vegetable oil
    (forget what kind it was) - and the glass completely vanished. The
    index of the oil matched perfectly that of the glass.

    Point being - just 'filling the scratches' won't do it - if the filler
    refracts light differently than the material it's filling, then it
    won't work at all.


    BD
     
    The Central Scrutinizer, Mar 7, 2006
    #4
  5. _jk_

    Salmon Egg Guest

    More years ago than I want to remember, I needed to polish some plastic
    insulating spacers to prevent surface leakage. I do remember that I dealt
    with several different plastics such polystyrene and PMMA. I tried several
    different abrasives such as cerium dioxide and rouge. Each combination of
    plastic and abrasive seemed to require a different vehicle to prevent
    scratching. Choice of a pad could be important as well.

    Bottom line: It can be done, but you have to determine, by hook or crook,
    which combination will work.

    When you are done, you will probably have lousy surface quality anyway.

    Bill
    -- Ferme le Bush
     
    Salmon Egg, Mar 7, 2006
    #5
  6. When you are done, you will probably have lousy surface quality anyway.

    Isn't it more the case that when you're polishing, you're simply
    removing material, regardless of how smooth the final surface is? And
    when you remove material you change the focal characteristics of the
    lens - so you could remove the scratches, but you'll be baffled as to
    why the heck you get headaches so much now!!
     
    The Central Scrutinizer, Mar 7, 2006
    #6
  7. _jk_

    CatmanX Guest

    Do they make plastic lenses in poland?

    well you learn something new every day.

    dr grant
     
    CatmanX, Mar 8, 2006
    #7
  8. _jk_

    _jk_ Guest

    Good point. I didn't think there would be much refractive effect in a
    thin layer. I wonder what the mystery vegetable oil was. Sounds like
    it would be nice to have the equivalent for plastic lenses.

    Thanks to all for the help.

    (I'll let you know how the vegetable oil works on my glasses <g>)
     
    _jk_, Mar 8, 2006
    #8
  9. _jk_

    Dr. Leukoma Guest

    I've heard two basic arguments over the years. One has to do with
    federal regulations regarding minimum thickness and the other argument
    has to do with reworking the lens not being cost-effective.

    DrG
     
    Dr. Leukoma, Mar 8, 2006
    #9
  10. An "old farm wife" remedy for scratched eyeglasses is good
    old-fashioned Lemon Pledge. Coat em up, polish it off with a smooth
    cloth, and you have darn near 48 good hours before you need to do it
    again.
     
    doctor_my_eye, Mar 8, 2006
    #10
  11. I wonder what the mystery vegetable oil was.

    It was corn oil.

    I remembered that the TV show I saw the demo on was Daily Planet, so I
    tracked down a small writeup on the premise...

    http://exn.ca/Stories/2002/02/04/52.asp

    "The key here is that the index of refraction of the corn oil and the
    pyrex glass are virtually identical. Therefore, when the glass is
    immersed in the corn oil, it bends light to exactly the same degree as
    the surrounding liquid and thus disappears. There is no way to
    distinguish it from its surroundings."

    True, there may be little effect when a material of a different
    refractive index is used for filling tiny scratches in lenses; but the
    premise is sound...
     
    The Central Scrutinizer, Mar 8, 2006
    #11
  12. _jk_

    Quick Guest

    I wonder what Rain-X would do to them?

    if they survive that and it doesn't work you
    could try Armor-all?

    -Quick
     
    Quick, Mar 8, 2006
    #12
  13. _jk_

    Salmon Egg Guest

    Even if the index is not correct, it might help. It is the relative index
    that counts. Thus, a lens material of index 1.5 immersed in a water of index
    1.33 would have a reflectivity of 0.36% at the interface while the same lens
    in air would have a reflectivity of 4.00%. Nevertheless, scratches will not
    reflect the same way as plane surfaces do.

    Bill
    -- Ferme le Bush
     
    Salmon Egg, Mar 8, 2006
    #13
  14. _jk_

    The Real Bev Guest

    600 Wetordry sandpaper does NOT work, it just makes the matter worse.
    Neither does the plastic polish designed for plastic motorcycle windshields.
    It doesn't work on plastic motorcycle windshields either.

    Filling the tiny bubbles in big aero camera lenses with nail polish or black
    paint worked fine to prefent light scattering, but I'm pretty sure that
    wouldn't work with spectacles.
     
    The Real Bev, Mar 14, 2006
    #14
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