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Thread: 1.56 Semifinished SV Photochromic w/ AR

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    1.56 Semifinished SV Photochromic w/ AR

    I have a company buying 1.56 Semi finished Photochromic w/ front surface AR. After they surface the lenses they apply a UV curable hard coat to the back surface. The cure time is 7 - 10 seconds. After the curing they find spider web cracks in the AR coating. They do not have this problem with any other Semi finished lens product that has front AR.

    Any explanations and advice would be appreciated.

    Doc
    Last edited by DocInChina; 11-12-2007 at 04:59 PM. Reason: It should have read 7-10 seconds, not minutes. My bad.

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    ATO Member HarryChiling's Avatar
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    The base lens might not be fully cured before the AR is applied. Or the primer the AR is stacked on may not be fully cured. Just some suggestions to check out.
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    Quote Originally Posted by HarryChiling View Post
    The base lens might not be fully cured before the AR is applied. Or the primer the AR is stacked on may not be fully cured. Just some suggestions to check out.
    I also often face the spider web crack in the AR coating against SOLAMax. Any advise?

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    Quote Originally Posted by Samuel Jong View Post
    I also often face the spider web crack in the AR coating against SOLAMax. Any advise?
    I did more research about this the past few days. 1.56 Photochromic is a softer material and likely more prone to thermal expansion thus causing the crazing of a front AR applied to a semi-finished lens. In fact all resin lenses will expand but some more than others. There is a patent that I found online that has method(s) of keeping the lens cool during the application of the back hard coating.

    http://www.freepatentsonline.com/20050008774.html

    Doc

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    Quote Originally Posted by DocInChina View Post
    I have a company buying 1.56 Semi finished Photochromic w/ front surface AR. After they surface the lenses they apply a UV curable hard coat to the back surface. The cure time is 7 - 10 minutes. After the curing they find spider web cracks in the AR coating. They do not have this problem with any other Semi finished lens product that has front AR.

    Any explanations and advice would be appreciated.

    Doc
    Just sounds like an awful long time for UV curing. The Ultra Optics UVNV cures in seconds.

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    Quote Originally Posted by gemstone View Post
    Just sounds like an awful long time for UV curing. The Ultra Optics UVNV cures in seconds.
    This is what happens when I do not sleep. It should read 7-10 seconds, not minutes.

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