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Railfan Technology > How to remove "silvering" from old B&W negative emulsion


Date: 06/24/21 07:31
How to remove "silvering" from old B&W negative emulsion
Author: Frisco1522

I've been collecting old negatives for many years and at one time back in the early 70s Joe Collias gave me a copy of a procedure that Gerald Best or some other pro used to clean the emulsion on old B&W negatives, particularly the silvering.
Back then, I cleaned one big batch of Post Card negatives and it worked beautifully.  Problem is, somewhere along the way I lost the sheet with the instructions.
I remember using cotton swabs and a liquid.  For the life of me I can't remember what it was.   I have some negs in deep need of "desilvering".
A friend told me he uses a soft white eraser to do it, but I cringe at the thought of rubbing an eraser over film emulsion.
TIA



Date: 06/24/21 08:31
Re: How to remove "silvering" from old B&W negative emulsion
Author: ironmtn

 Hi, Don. Here's a website that may help: https://www.conservation-wiki.com/wiki/PMG_Silver_Mirroring#Physical_Abrasion_or_Manipulation_to_Reduce_Silver_Mirroring
No clear "do this" recommendations, but a competent basic discussion of of the pros and cons of various methods in the context of the material and the chemistry involved.

Here's another website from a professional conservator which does discuss some methodology: https://ritaudina.com/en/2018/10/14/silver-mirroring-removal-from-historical-photographs/

There are other sites that discuss "silvering" and other preservation issues (such as ferrotyping), but they don't often make any suggestions about techniques to mitigate such processes. But they're worth reading to know exactly what you are dealing with, and properly identifying it, so you can use the proper technique, if one is available.

A good simplified overview site to properly recognize the issue, which can be important for the treatment, if any: https://www.filmcare.org/vd_silvermirroring.php

And two more technical guides oriented more to professional conservators:
https://gawainweaver.com/images/uploads/Weaver_Guide_to_Gelatin_Silver.pdf
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_silver_gelatin.pdf

I never treated any film for "silvering" or other issues in past work in archival photo collections that I worked with professionally. Our emphasis was always on proper long-term archival storage of the original forms, and best-available-quality duplication to other more stable media for preservation of the image that was in a perhaps irreversible state of long-term degradation. Arresting and / or mitigating natural processes of decomposition of any historical material always has some issues, and a medical-like "first do no harm" ethic is involved.

All of that said, I seem to recall having done something in terms of active treatment a few times on some sheet film negatives (that awful old "pack film", what was it, 122-size?) of old family photos in my own personal collection. They were interesting, but not of particular historical value, and I had prints or scans, so I was willing to take a chance. My recollection is that I used a solution based on Kodak Photo-Flo (don't recall the mixture), and that it helped a bit and did not cause any damage. The link in the first-above citation mentions the use of Photo-Flo. Those of us who did darkroom work in the past almost certainly used Photo-Flo as a wetting solution to minimize water spots on drying film after development. It always worked well for me in that role, and it's still pretty readily available from photo stores like B&H and others that sell darkroom chemicals and equipment.

Good luck with your search and work. I hear many good things about the Frisco steam book, and mine is on order. Can't wait to get it.

MC



Date: 06/25/21 07:02
Re: How to remove "silvering" from old B&W negative emulsion
Author: Frisco1522

I ended up using the magic eraser on the one I wanted to scan.  Took a while and made me nervous but it worked.
I've never attempted to remove silvering from prints. 
Thanks for the info.



Edited 1 time(s). Last edit at 06/26/21 07:09 by Frisco1522.



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