Let’s talk about Delamination

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Scoper
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Let’s talk about Delamination

#1 Post by Scoper » Wed May 24, 2023 4:20 pm

Recently I was using a scope with Leitz EF objectives (4x,10x,40x and 100x). The 4x and 10x objectives worked well..the 40x and 100x has lines across their viewing fields and were a bit out focus no matter what I did. Checking and cleaning the optics in the optical train made no significant improvement.

As I pondered the problem, I was handling the pair of Leitz Periplan 10x eyepieces being used and saw a SMALL discrepancy in one of the eyepieces. Upon much closer inspection, one could just barely see delamination in BOTH eyepieces. After using many scopes over the years, this is the first I have seen delamination in eyepieces..usually it occurs in objectives.

Comments on this?

Scarodactyl
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Re: Let’s talk about Delamination

#2 Post by Scarodactyl » Wed May 24, 2023 11:55 pm

Zeiss eyepieces from the finite era do it all the time. Otherwise it isn't super super common but can happen, especially to ones that weren't kept well.

Scoper
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Re: Let’s talk about Delamination

#3 Post by Scoper » Wed May 24, 2023 11:58 pm

I too have seen the “Zeiss Curse”…really sad to see a beautiful piece of craftsmanship ruined.

The Leitz eyepieces were a surprise and easily overlooked.

apochronaut
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Re: Let’s talk about Delamination

#4 Post by apochronaut » Thu May 25, 2023 1:55 am

I think the early synthetic cements were made in Delami. That nation isn't known for it's high quality industrial production so it was probably cheap. B & L obviously bought heavily into stuff from Delami. Some of their eyepieces should be in the Museum of Failed Products, which does exist.

Scoper
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Re: Let’s talk about Delamination

#5 Post by Scoper » Fri May 26, 2023 6:55 pm

A question…is delamination worse for the viewing experience when it occurs in the eyepieces or the objectives?

How about in the condenser or intermediate lens?

Scoper
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Re: Let’s talk about Delamination

#6 Post by Scoper » Fri May 26, 2023 6:58 pm

I have read a number of theories as to why it occurs.

Wrong type of cements, improper storage conditions, vibration/shock, the phase of the moon…in other words many guesses and no real documented evidence.

Any thoughts on this?

Hobbyst46
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Re: Let’s talk about Delamination

#7 Post by Hobbyst46 » Fri May 26, 2023 8:00 pm

Scoper wrote:
Fri May 26, 2023 6:55 pm
A question…is delamination worse for the viewing experience when it occurs in the eyepieces or the objectives?

How about in the condenser or intermediate lens?
Many condensers consist of single lenses (not doublets formed by cementing) so no delamination is expected.
In principle, all glass doublets might be delaminated. However, experience shows that some specific products from the past are much more vulnerable, for one reason or another.
IMO, delamination in the objectives is liable to ruin the image quality more than delam in the other optical parts. Cannot prove it though.
Besides, A typical microscope setup includes many more objectives and several eyepieces, but only 1-3 condensers, so the discussions mostly involve objectives and eyepieces. Not exclusively.

Hobbyst46
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Re: Let’s talk about Delamination

#8 Post by Hobbyst46 » Fri May 26, 2023 8:22 pm

Scoper wrote:
Fri May 26, 2023 6:58 pm
I have read a number of theories as to why it occurs.

Wrong type of cements, improper storage conditions, vibration/shock, the phase of the moon…in other words many guesses and no real documented evidence.

Any thoughts on this?
What is wrong in the "theories" ? the behavior of glass and cements under different ambient conditions is well known, sufficiently so that each one of the factors: high temperatures, high humidity, repeated warm-cool cycles, vibrations, is able to break the glass-cement bond and cause separation. It is documented, maybe not within microscopy literature but very probably as part of material science and technology and engineering. And it appears that modern glass technology has found better and resistant cements.

The phase of the moon is probably harmless to microscopy, but to be on the safe side and avoid delamination, microscopy sessions should only be run by daylight, when the moon is usually invisible.

Phill Brown
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Re: Let’s talk about Delamination

#9 Post by Phill Brown » Fri May 26, 2023 8:34 pm

Poor choice of cement.
For many manufacturers it's very uncommon but not a never event, for some it's almost a given by the sound of it.
Dropping an objective onto a hard surface can damage the best of them.
It happens.

Scoper
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Re: Let’s talk about Delamination

#10 Post by Scoper » Fri May 26, 2023 10:05 pm

My guess is a combination of unstable cements (keeping mind many of these optics are many decades old), drastic temperature extremes (too hot, too cold or rapid temperature changes), different expansion rates for the glasses and their mountings.

Every chain has a weak link and the boundary between glass elements with its cement is likely it in an optical train.

I also agree to be safe one considers the moon phase. ;<)

apochronaut
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Re: Let’s talk about Delamination

#11 Post by apochronaut » Sun May 28, 2023 6:24 pm

De-lamination doesn't just have one characteristic and because there are different cement formulas, each formula fails somewhat differently as well as differently due to cause.
Balsam was the problem cement for Zeiss short objectives, the problem cement for Spencer short objectives, not much of a problem for B & L and then they paid for it when they switched to synthetic cement. Balsam failures tend to be due to excessive drying and oxidation, similar to those on old prepared slides, with the cement hardening and crazing or creating concentrated swirls, likely following the pattern of deposition. Sometimes it has not entered into the optical sweet spot yet and can be reversed with a combination of heat and solvent.
Some synthetic cements seem vulnerable to long adverse chemical reactions and or photo chemical reactions possibly. It seems that the Bausch & Lomb early synthetic cement problems are worse in objectives that have been used. I have seen crystals, milkiness, bubbles, or a generalized haze with synthetic cements. Not cracking yet. Relatively high heat ( 270 F.) has healed some objectives but there are now a lot of different cements.

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Crater Eddie
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Re: Let’s talk about Delamination

#12 Post by Crater Eddie » Wed May 31, 2023 7:42 pm

LOMO objectives of a certain age are particularly prone to delamination. Don't ask me how I know this. :oops:
I have never seen it in eyepieces though.
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Re: Let’s talk about Delamination

#13 Post by tpruuden » Mon Jul 10, 2023 1:33 am

How is the modern Zeiss stuff doing, any known problems?

Adam Long
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Re: Let’s talk about Delamination

#14 Post by Adam Long » Wed Nov 08, 2023 11:35 am

Just had an interesting delamination experience.

I bought a 10x Zeiss Planapo as an upgrade to my 10x Neofluar. The box was on my step when I got home from work on Friday. I unpacked it and attached it to my Universal. Immediately I saw a problem - I couldn't get a sharp image. The overall image was ok but the fine detail wouldn't come sharp. I compared it to the NF - it was clearly worse. Focusing through the objective with the betrand lens, a large central patch of delamination was obvious. Disappointing, but always a risk buying these old objectives (I'd guess this is 1960s). I put the objective back in the box to return.

On checking I found the seller 'doesn't accept returns' so messaged him and waited. No reply. I looked at the ebay return policy and photos are required as evidence. Hmm, could be tricky. This morning (four days later) I remounted the objective to see what I can do and was amazed to find it functioning perfectly, with an slight increase in sharp detail over the Neofluar, and absolutely nothing visible in the back focal plane.

I can only imagine the temperature change of the cold delivery van/ step to my warm house caused the issue. Really surprising how it could go from a serious problem to totally fine though! Food for thought...

Scoper
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Re: Let’s talk about Delamination

#15 Post by Scoper » Wed Nov 08, 2023 1:21 pm

Approximately how many degrees difference was it?

Adam Long
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Re: Let’s talk about Delamination

#16 Post by Adam Long » Wed Nov 08, 2023 1:52 pm

10, maybe 15 max.

apochronaut
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Re: Let’s talk about Delamination

#17 Post by apochronaut » Wed Nov 08, 2023 2:04 pm

Condensation possibly. Cold metal and glass and a warm humid hand can do it immediately and it will cling for a considerable time until the barrel and glass warms up. The heavier and more complex the objective the more likely that, as a potential brief annoyance.

Alexander
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Re: Let’s talk about Delamination

#18 Post by Alexander » Wed Nov 08, 2023 4:02 pm

tpruuden wrote:
Mon Jul 10, 2023 1:33 am
How is the modern Zeiss stuff doing, any known problems?
Just had to repair an eye-piece from a first generation Axioskop. It was terribly de-laminated.
There is a good chance to repair de-lamination if you are able to disassemble the item.

Adam Long
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Re: Let’s talk about Delamination

#19 Post by Adam Long » Thu Nov 09, 2023 10:03 am

apochronaut wrote:
Wed Nov 08, 2023 2:04 pm
Condensation possibly.
I don't think it was. I had a good look at the objective and couldn't see any, however there was a patch with the characteristic oily interference colours.
There is a good chance to repair de-lamination if you are able to disassemble the item.
Yes, I've had a lot of success with eyepieces and telan lenses. However all of these were delaminated in a ring around the outside. Objectives are another matter though, and this was in the centre, I have an Axio eyepiece which shows the same, but permanent. I've wondered about heating it, but it probably needs the elements completely separating and recementing.

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Re: Let’s talk about Delamination

#20 Post by iPeace » Sun Dec 03, 2023 12:29 am

Alexander wrote:
Wed Nov 08, 2023 4:02 pm

Just had to repair an eye-piece from a first generation Axioskop. It was terribly de-laminated.
There is a good chance to repair de-lamination if you are able to disassemble the item.
How does one go about repairing a delaminated eyepiece? I have a Zeiss PM III with one eyepiece that has visible delamination into about 1/6 of the field diameter.

Alexander
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Re: Let’s talk about Delamination

#21 Post by Alexander » Sun Dec 03, 2023 9:45 am

iPeace wrote:
Sun Dec 03, 2023 12:29 am

How does one go about repairing a delaminated eyepiece? I have a Zeiss PM III with one eyepiece that has visible delamination into about 1/6 of the field diameter.
You have to disassemble the eye-piece. There is one optical element consisting of two lenses glued together. The delamination is in the glue. Put the element into xylene for a few days. Then carefully place some Ceadax around the border line between the two lenses and put it into a xylene saturated environment for some more days. Clean the element with xylene from any residue and reassemble.

iPeace
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Re: Let’s talk about Delamination

#22 Post by iPeace » Mon Dec 04, 2023 6:10 pm

So you're not dissolving the cement (canada balsam, I assume) to the point of separating the lenses, but rather just softening it and introducing some fresh cement to fill the gap, right?

Does the full-body soak damage the anti-reflective coatings on the exposed faces?

The lens pair in question has some chips where the two elements meet, and there is a bit of fill of clear cement at the same point. I imagine the previous owner tried to pry the elements apart with a screwdriver and when that didn't work, put a blob of cement hoping to fill the delamination. So nice when sellers conceal damage, something I could never do as a seller.

Alexander
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Re: Let’s talk about Delamination

#23 Post by Alexander » Mon Dec 04, 2023 8:37 pm

It is not about separating the two lenses. The xylene just soakes in, softens the borderline and is a transport medium for the applied cement.
The coating is made of minerals and resistant against xylene. It is not perfectly resistant against mechanical threatening though.

What should I say about sellers?

apochronaut
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Re: Let’s talk about Delamination

#24 Post by apochronaut » Tue Dec 05, 2023 10:27 am

Are you sure it is Canada Balsam? Lens separation has differing characteristics based on the cement type. With Canada balsam the separation is true separation due to the drying out of the balsam. It usually crazes or develops what appear to be air pockets. The drying of the balsam separates it from one or both lens surfaces.
Sometimes the balsam can be softened with ethanol and the lenses clamped ( I use very light pressure between two corks). The balsam will dissolve and redistribute evenly between the now thinner space between the lenses. It hasn't always worked but if not I just separate them and recement them with balsam.

If it is a synthetic cement , the early ones had problems which don't resemble those of balsam. There is often a cloud in the cement , an uneven swirling or even crystals, depending on the cement. Some were uv cured and may have not been cured properly. Sometimes heat can melt and redistribute it, clamped as above but the solvents needed are pretty heavy duty and cement specific.

iPeace
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Re: Let’s talk about Delamination

#25 Post by iPeace » Tue Dec 05, 2023 9:25 pm

apochronaut wrote:
Tue Dec 05, 2023 10:27 am
Are you sure it is Canada Balsam?
I don't know what cement was used. It is the eyepiece from a Zeiss PM III, so mid-seventies vintage. The center is perfectly clear, but there are about a dozen semicircular incursions from the perimeter that look grainy.

apochronaut
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Re: Let’s talk about Delamination

#26 Post by apochronaut » Wed Dec 06, 2023 4:57 am

Is the delaminated lens, the eyelens or the field lens? Eyepiece designs that employed a singlet-doublet arrangement could have the doublet in either location.

iPeace
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Re: Let’s talk about Delamination

#27 Post by iPeace » Wed Dec 06, 2023 6:53 am

The lens closest to the eye is a single lens. The lens furthest from the eye is a doublet.

Hobbyst46
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Re: Let’s talk about Delamination

#28 Post by Hobbyst46 » Wed Dec 06, 2023 1:17 pm

iPeace wrote:
Wed Dec 06, 2023 6:53 am
The lens closest to the eye is a single lens. The lens furthest from the eye is a doublet.
Is it a KPL or KPL-W eyepiece ? your description of the issue does indeed indicate delamination.

MichaelG.
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Re: Let’s talk about Delamination

#29 Post by MichaelG. » Wed Dec 06, 2023 1:47 pm

It’s stretching the range of this discussion … but there’s some interesting information here:
http://trioptics.com/products/opticentr ... ledge-base

MichaelG.
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apochronaut
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Re: Let’s talk about Delamination

#30 Post by apochronaut » Wed Dec 06, 2023 3:29 pm

The style the damage takes though, is symptomatic of an invasion of a solution from the outside that has caused the problem, not a natural failure of the cement. The regular semi-circular incursions seem like a pattern csused by an invading liquid, as if someone has tried to clean the leading surface of the field lens with some solution that has crept down between the lens edge and barrel and got trapped there long enough to partially dissolve or soften the periphery of the cement layer. If it is balsam, many solvents could do that but those that evaporate slower would be more likely candidates.
Try the same thing along the edge of a lousy prepared slide and you can mimic the same pattern.
If I were repairing that, I would use pressure to even out the "waves" when redissolving the cement.

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