Originally Posted by topaz
Thanks for your replies. I ordered some Milsolve. I really enjoy using Rolleiflex. For some applications, My 501cm is best and for others my Mamiya C330 is excellent. Closeups especially. There is something about some of the images captured by Rollei that have a certain quality that appeals to me. The separation is minor. It appears as a darkened area in the middle of the rear cemented elemants. You see, I sent the front element to Focal Point. It was terribly scratched. John did an excellent job at polishing and recoating. Really nice. The end cost was more than estimated, and I am loathe to put more into this venerable camera.
I will, however soak the element for a month if that is what it takes. Could be an enjoyable project. V blocks. Clean room.
I made my own Canadian Balsam/Xylene solution. Heated, and repeatedly filtered through Melita paper filters. Appears nice and clear. Easy to separate if I am not happy with my first try.
I'll be waiting for news of your progress with this with great interest. I'd be inclined to use CB myself I think, for the reasons you've mentioned. Having the V blocks is good to hear, because I was going to enquire about your alignment process. Bear in mind that Paul told me he soaked the Teleskop cell in Milsolve for a couple of months before the pieces finally yielded, so if you can bear to be without the use of the camera, don't necessarily abandon hopes of success with chemical separation if they haven't parted after three or four weeks, as it may well take longer.
Although the Contaflex SLRs have little in common with your Rollei (other than that they both use lenses manufactured by Zeiss, at around the same time), as you're interested in the problem of Zeiss cement separation, here are some links courtesy of Pacific Rim Camera, with images of the lenses involved. Firstly, the Teleskop lens of a type that Paul repaired (I have a good condition copy of this lens myself).
shows the optical array of the Teleskop. And this page
shows photos of the Pro Tessars made for the later Contaflex models which have been badly affected by cement separation. Various Zeiss lenses are known to suffer from the problem, including the occasional 2.8 Planar Rolleiflex lens, and (much more frequently) the 135mm Sonnar used in the Tele Rolleiflex. But for whatever reasons, it is the Contaflex lens system, particularly the Pro Tessars (but also occasionally the Teleskop for Contaflex I and II), which are the most often afflicted.
I have a Contaflex I on hand with a prism that has a lot of brown discolouring within it (it's one of a number I have so it is not a priority but I will eventually swap a spare prism into it and service it). The deterioration in the prism joints is not synthetic cement separation. It looks exactly like Canada Balsam that's aged and gone bad and I don't have any doubt that this is what was used to make it.
The first Contaflexes were sold in late 1953 so I believe Zeiss were still using Canada Balsam, for at least some purposes, in the early 1950s. At some point early in the decade they began substituting a synthetic alternative instead. It didn't always fail, even in the case of the Contaflex lenses. Although good examples of the 85mm type (which is the single lens type most often affected, based on my extensive observations of Contaflex and Rollei eBay listings over a number of years) are the exception rather than the rule, sound specimens are still out there. I have one slightly affected 85mm f/4, and also a 85mm f/3.2 that is still perfect. These lenses were made in the mid-1950s to early 1960s for the most part, I believe.
So what is clear to me is that in the period from the early to mid 1950s onwards, Zeiss were still getting the process of using synthetic cement perfected. Sometimes the optics would manifest no problems decades later, other types of lenses would display a frequent tendency to fail.
Of course, there are other types of Zeiss lenses that can be affected, it's not confined to their Contaflex and Rolleiflex optics. For instance, the Oberkochen 50mm f/1.5 Sonnars for the Contax rangefinders will begin to fail on occasion, and prospective purchasers of this lens need to keep an eye out for signs of it when inspecting these, too.
In light of this, I think you've drawn something of a short straw, because the 3.5 Planars aren't notorious for cement problems in their rear groups (unlike the aforementioned Pro Tessars or 135mm Sonnar, for which I would argue the term "notorious" is *not* an exaggeration). All this is mostly off topic for your Rolleiflex, but maybe it helps put a little context on the scope of problem you are trying to remedy?