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Thread: Any tips on how to repair lenses with Balsam Separation?

  1. #11

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    Re: Any tips on how to repair lenses with Balsam Separation?

    Quote Originally Posted by Tin Can View Post
    Flash point 120 F

    Melt 160 F
    Good info... so boiling water should work. Maybe the detractors just didn’t boil long enough or, as Dan suggests, was boiling a lens with something other than Canada Balsam.

    I also recall reading something on the internet where it was suggested to heat the element, concave side up, in a 300 degree oven for a while and the balsam might smooth out and any bubbles flow to the edges and escape. Wouldn’t that be nice???

  2. #12
    Between here and there
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    Re: Any tips on how to repair lenses with Balsam Separation?

    I know Steven Tribe has done a good few (?) of these ... maybe there is something of worth in the thread here:
    https://www.largeformatphotography.i...=canada+balsam even if it has lost many photos.

    Perhaps he'll join with some tips.
    "Be still and allow the mud to settle."

  3. #13

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    Re: Any tips on how to repair lenses with Balsam Separation?

    Quote Originally Posted by Dan Fromm View Post
    What are the lenses? I ask because modern lenses don't use Canada balsam. The adhesives that replaced it aren't softened by heat.
    Theyíre Bronica GS-1 lenses, specifically the Zenzanon-PG 65mm F/4 and Zenzanon-PG 100mm F/3.5. The GS-1 and itís associated lenses were made sometime between 1983 and 2002, so itís safe to say they are indeed modern lenses. That said, Iím not really expecting the lens elements to separate, but I think itís worth a shot to try. Bronica GS-1 lenses are known to be pretty sharp; I have three other Bronica GS-1 lenses and can confirm. I would absolutely love to rehabilitate these two lenses, as they are in otherwise flawless condition.

    If the heat canít separate the lens elements, does anyone have any suggestions of what possibly could?

  4. #14

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    Re: Any tips on how to repair lenses with Balsam Separation?

    Try soaking in acetone.

  5. #15
    Drew Bedo's Avatar
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    Re: Any tips on how to repair lenses with Balsam Separation?

    For minor separation, I have wrapped the dismounted lens cell or element in a dish towel and put it into an oven at the lowest setting (20F to 150F but no higher) for an hour or so, but starting with the oven cold. I turn the oven off and let it cool. Somewhat later on, I take the still wrapped glass out ofg the oven and set it aside to continue to cool.

    Eventually I unwrap it and give it a close look. Sometimes that works out well.

    If there is still a separation problem, I take it all in to Professional Camera Repair here in Houston and they can fix it.
    Drew Bedo
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  6. #16
    (Shrek)
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    Re: Any tips on how to repair lenses with Balsam Separation?

    I've had better luck with MEK paint/furniture stripper than heat for separating lens elements, whether Canada balsam or modern UV-cure glue. Also re-assemble with UV-cure glue instead of balsam, easier to work with, available pretty cheap from some Chinese sellers.

  7. #17

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    Re: Any tips on how to repair lenses with Balsam Separation?

    MEK will probably do it eventually. I have used it to undo learning mistakes using modern UV cure cements on protar lenses. But it can take weeks as it slowly works its way in, and I didn't fully cure the lens cement before realizing I would be doing it over.

    Summers Optical has something for this, but it is toxic and highly flammable, and must be used over a certain type of hot plate with no visible red-glowing heating element.

  8. #18

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    Re: Any tips on how to repair lenses with Balsam Separation?

    If I remember correctly, the way to tell the cement is to shine UV (blacklight), balsam cement stays clear but UV cements glow...

    Steve K

  9. #19
    Nodda Duma's Avatar
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    Re: Any tips on how to repair lenses with Balsam Separation?

    It won’t be Canada balsam if made in that timeframe, and you won’t be able to separate with heat (and you’ll crack the lens if you do). Instead You’ll need to separate by soaking in methylene chloride, checking every week or so. A better mix is 100 parts methylene chloride, 15 parts methanol, 3 parts ammonia (26%). Probably take about three weeks. Btw that works very well on balsam..just a day or two. No need to heat up. Then, clean and rebond with UV cure adhesive. Recommend using Norland 61, which is very likely what was originally used.

    When rebonding, clean very thoroughly. You want every speck to be gone. Use Kimwipes to clean btw. Lightly blow Canned air Immediately prior bonding. Drop two or three drops Of NOA61 onto the concave surface. Set the other element on top, press down while moving the element in a circle on top of the other. The adhesive will distribute with pressure and swirlies. Get rid of all air bubbles. Once distributed, whack it with a UV light for a few seconds to precure. The adhesive will be a little less fluid. Re-check center. Once satisfied, expose to UV until cured. Constantly check center. Clean excess adhesive with acetone. Repaint edges then you’re done.
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  10. #20

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    Re: Any tips on how to repair lenses with Balsam Separation?

    Quote Originally Posted by Nodda Duma View Post
    It won’t be Canada balsam if made in that timeframe, and you won’t be able to separate with heat (and you’ll crack the lens if you do). Instead You’ll need to separate by soaking in methylene chloride, checking every week or so. A better mix is 100 parts methylene chloride, 15 parts methanol, 3 parts ammonia (26%). Probably take about three weeks. Btw that works very well on balsam..just a day or two. No need to heat up. Then, clean and rebond with UV cure adhesive. Recommend using Norland 61, which is very likely what was originally used.

    When rebonding, clean very thoroughly. You want every speck to be gone. Use Kimwipes to clean btw. Lightly blow Canned air Immediately prior bonding. Drop two or three drops Of NOA61 onto the concave surface. Set the other element on top, press down while moving the element in a circle on top of the other. The adhesive will distribute with pressure and swirlies. Get rid of all air bubbles. Once distributed, whack it with a UV light for a few seconds to precure. The adhesive will be a little less fluid. Re-check center. Once satisfied, expose to UV until cured. Constantly check center. Clean excess adhesive with acetone. Repaint edges then you’re done.
    Whoa! Thank you so much for this! You just saved an otherwise flawless Bronica lens from probable destruction, as I was planning on boiling the “balsam separated” lens element in my effort to fix it tonight. (In this case, would it still even be called “balsam separation”?)

    I did a cursory search on Google and couldn’t find methylene chloride easily available in my area (and I live in Los Angeles!). Apparently you can’t get this at Home Depot. Is there a pre-mixed compound of methylene chloride, methanol, and ammonia available for optical situations/problems like this?

    Regarding optical UV glue, I take it that any old optical UV glue from Amazon won’t work, will it? Also, would it be safe to assume that Norland 61 has some sort of special optical property that Canada balsam doesn’t have? (I just bought a little bottle of Canada balsam from Amazon before even starting this thread, unfortunately.)

    Anyway, many thanks again! I appreciate it.
    Last edited by manfrominternet; 14-Oct-2020 at 00:38.

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