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Any tips on how to repair lenses with Balsam Separation?

Created: 2022-04-29 21:57 Updated: 2022-04-29 21:57 Source: https://www.largeformatphotography.info/forum/ Notebook: All Photography


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  1. 12-Oct-2020, 03:40 #1
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    Any tips on how to repair lenses with Balsam Separation?

    Hi all,

    So I bought two lenses suffering from Balsam Separation on the cheap that I would like to try and fix. Since they were bought cheaply, I’m not worried if I totally destroy them. The inner-rear elements that had been cemented together with Balsam that has since separated and has created somewhat of a foggy haze inside that would absolutely affect shooting.

    As far as I have researched, here are the general steps that were recommended to take when repairing a lens with this type of damage.

    1.) The tools needed for this are: a spanner wrench (to unscrew the the rings holding the lens elements), Canada Balsam (to reglue the glass elements), double boiler (to boil the balsam-cemented lens elements), lots of microfiber cloth (to line the double boiler so that the glass elements don’t scrape/scratch against the metal of the double boiler as it’s boiling), and gloves and a super clean environment (for obvious reasons).

    2.) Unscrew and remove the problematic balsam-separated lens element(s). Mark a line along the side of the balsam-separated lens elements (so that you know how to assemble it back together), and put the lens elements in double boiler lined with microfiber cloth, and put in a good amount of room temperature water.

    3.) Heat up water slowly - with balsam-separated lens element inside - until it boils. If boiled too fast, you run the risk of cracking the glass.

    4.) After anywhere from a few minutes to a few hours, remove lens element from boiling water and let it cool down a little bit for handling. The lens elements, after being boiled, should separate easier.

    5.) After separating lens elements, clean thoroughly and let dry.

    6.) Now put on a little bit of new Canada Balsam on one of the elements and “sandwich” lens elements back together, squeezing out any bubbles, using the lines you marked earlier as your guide.

    7.) Wait a few hours or a full day and reassemble the lens.

    This is my basic understanding of how to fix a balsam-separated lens.

    Do you guys/experienced pros have any tips or suggestions?

    Many thanks!
    Last edited by manfrominternet; 12-Oct-2020 at 13:18.
  2. 12-Oct-2020, 04:53 #2
    Join Date:
    Dec 2011
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    Re: Any tips on how to repair lenses with Balsam Separation?

    I suggest you proceed

    Shortly some will tell you to not do it
    Local Hobbyist
  3. 12-Oct-2020, 05:19 #3
    Join Date:
    Dec 2005
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    Re: Any tips on how to repair lenses with Balsam Separation?

    No experience here... but read internet in the past. I seem to recall that balsam melting temp was higher than the temp of boiling water. Might want to check that out. Good luck; sounds like you have little to lose so will be a fun experiment.
  4. 12-Oct-2020, 05:50 #4
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    Re: Any tips on how to repair lenses with Balsam Separation?

    Cannot find melting temp yet

    This has a lot of good info

    https://www.naturalpigments.com/cana...%20deteriorate.
    Local Hobbyist
  5. 12-Oct-2020, 06:01 #5
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    Re: Any tips on how to repair lenses with Balsam Separation?

    Local Hobbyist
  6. 12-Oct-2020, 06:57 #6
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    NJ
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    Re: Any tips on how to repair lenses with Balsam Separation?

    What are the lenses? I ask because modern lenses don't use Canada balsam. The adhesives that replaced it aren't softened by heat.
  7. 12-Oct-2020, 07:22 #7
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    Re: Any tips on how to repair lenses with Balsam Separation?

    Originally Posted by Tin Can
    Cannot find melting temp yet
    Apparently I couldn’t either or I may have remembered details. I recall someone that used a 300 degree oven to get the lens hot enough to separate, and another who set the lens on a 75 watt lightbulb... presumably incandescent.
  8. 12-Oct-2020, 07:27 #8
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    Re: Any tips on how to repair lenses with Balsam Separation?

    Interestingly, I recall that the guy using the lightbulb also used his tongue to verify alignment of the lens elements when reassembling. He said tongue is better misalignment detector than fingers and eyes.
  9. 12-Oct-2020, 07:51 #9
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    Re: Any tips on how to repair lenses with Balsam Separation?

    Flash point 120 F

    Melt 160 F
    Local Hobbyist
  10. 12-Oct-2020, 07:56 #10
    Join Date:
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    Re: Any tips on how to repair lenses with Balsam Separation?

    ONCE while soldering a live circuit on my AM transmitter, I needed a 3rd hand

    Put a wire in my mouth

    Shockingly bad idea

    I was 14

    Originally Posted by BrianShaw
    Interestingly, I recall that the guy using the lightbulb also used his tongue to verify alignment of the lens elements when reassembling. He said tongue is better misalignment detector than fingers and eyes.
    Local Hobbyist

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