Any tips on how to repair lenses with Balsam Separation?

[manfrominternet]

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!

[Tin Can]

I suggest you proceed

Shortly some will tell you to not do it

[BrianShaw]

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.

[Tin Can]

Cannot find melting temp yet

This has a lot of good info

https://www.naturalpigments.com/canada-balsam.html#:~:text=Details-,Canada%20Balsam%20is%20the%20pale%20yellow%20oleoresin%20with%20a%20faint,optical%20properties%20do%20not%20deteriorate.

[Tin Can]

https://web.archive.org/web/20070220153603/http://www.emsdiasum.com/summers/optical/cements/manual/manual.html

[Dan Fromm]

What are the lenses? I ask because modern lenses don't use Canada balsam. The adhesives that replaced it aren't softened by heat.

[BrianShaw]

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.

[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.

[Tin Can]

Flash point 120 F

Melt 160 F

[Tin Can]

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


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.

[BrianShaw]

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???

[Jimi]

I know Steven Tribe has done a good few (?) of these ... maybe there is something of worth in the thread here:
https://www.largeformatphotography.info/forum/showthread.php?58763-How-I-did-it-new-balsam-for-a-sick-RR&highlight=canada+balsam even if it has lost many photos.

Perhaps he'll join with some tips.

[manfrominternet]

What are the lenses? I ask because modern lenses don't use Canada balsam. The adhesives that replaced it aren't softened by heat.

They’re Bronica GS-1 lenses, specifically the Zenzanon-PG 65mm F/4 and Zenzanon-PG 100mm F/3.5. The GS-1 and it’s associated lenses were made sometime between 1983 and 2002, so it’s safe to say they are indeed modern lenses. That said, I’m not really expecting the lens elements to separate, but I think it’s 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 can’t separate the lens elements, does anyone have any suggestions of what possibly could?

[Dan Fromm]

Try soaking in acetone.

[Drew Bedo]

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.

[Jody_S]

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.

[Kevin Crisp]

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.

[LabRat]

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

[Nodda Duma]

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.

[manfrominternet]

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.

[Tin Can]

don't forget the correct fire suppression device

and children

[Randy]

I soaked my cell in acetone - took about a week for it to dissolve and easily come apart. After cleaning the elements up, rather than balsam I used a drop of canola oil. I suspect that it is not as "permanent" as balsam, but after about a year, it had not discolored. :) I have since sold the lens fully disclosing my procedure to the buyer.

[reddesert]

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.

Methylene chloride is a very strong solvent that is a significant health hazard (as in, touching it momentarily won't poison you, but major inhalation or skin exposure can cause various kinds of damage). Some paint strippers used it, but paint strippers with methylene chloride have been banned. I used it once years ago to build a slot processor by gluing acrylic. Maybe plastics stores still have it. However, you must use it cautiously.