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Camerafixer
Tinkerer
Username: Camerafixer
Post Number: 5
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 14, 2009 - 06:19 am: | 
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Hi - has anyone attempted to re-silver a pentaprism ? The pentaprims on my Olympus OM - 1N needs a partial re-silvering job.
Any suggestions or comments would be appreciated. |
Gez
Tinkerer
Username: Gez
Post Number: 133
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 15, 2009 - 03:13 am: |
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I guess the degraded foam around the eyepiece has caused 2 'desilvering' spots to appear??
It is best to just remove the foam and gently clean any contamination from the protective black paint. Don't be too enthusiastic as you may accidentally remove some of the aluminium coating that is still attached to the glass. Once the corroded aluminium has been removed he spots will not be so visible when looking through the viewfinder.
I have attempted cover similar spots with kitchen foil (bright surface downwards) glued in place with glass cement. The results have been OK but not brilliant.
The best solution is the vacuum deposition of a fresh coat of aluminium. I guess you are in the States, but a firm in London will do the job for 15GBP. However, for my next recoating job I'm going to approach a local mirror manufacturer, he should be able to recoat in silver for a lot less. |
Freegan
Tinkerer
Username: Freegan
Post Number: 2
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 10, 2009 - 03:08 am: |
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Dunno if this will help but from my chemistry days I partially recall a process that deposits silver on surfaces (including glass) using silver nitrate and ammonia solution among the ingredients.
Temperature control is also important as greater heat causes a granular effect which you will wish to avoid.
An extensive internet search might turn up the details of the process for you.
If you do find it, please share as all my notes on the subject are long gone and I can foresee it being of use to many of us.
Freegan. |
Gez
Tinkerer
Username: Gez
Post Number: 139
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 10, 2009 - 01:10 pm: |
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Fred, before you attempt silver coating by the Brashear method it is advisable to look at this safety memo, www.hse.gov.uk/foi/internalops/fod/oc/600-699/687_7.pdf
I haven't tried the procedure myself, but the critical parameter is getting the glass surface scrupulously clean. The cost of silver nitrate is prohibitive too. |
Freegan
Tinkerer
Username: Freegan
Post Number: 3
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 10, 2009 - 01:44 pm: |
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Gez,
Thanks for doing all the 'legwork'.
I tried the link but their server is currently too slow for my impatient browser so I'll check again later.
Regarding the cost issue, you're very probably correct that the materials cost would be the major stumbling block.
However, you may have deduced from my username that I'm a bit of a scavenger and a trawl of film developer labs and vintage photographic plate manufacturers (at least those that aren't yet out of business) might be productive.
Maybe one that is going out of business would welcome an enthusiast as a recipient of its redundant stock of silver salts.
Perhaps using the pentaprism housing as the bath for the prism might reduce the quantities of materials needed.
I'd still give this method some thought and a thorough costing, though.
Thanks again for reminding me of the name of the process.
Freegan |
Jon_goodman
Tinkerer
Username: Jon_goodman
Post Number: 42
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 10, 2009 - 06:30 pm: |
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Once upon a time about 3 or 4 years ago, I discovered there was a pentaprism that would swap with the OM-1/OM-2. I am stretching my memory now...it was either the OM-10 (easily available in parts camera form) or maybe the Zenit E. Sorry, but I can not recall. Leaning toward the OM-10. Good luck.
Jon |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 979
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 10, 2009 - 08:02 pm: |
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Yes, I think I recall the OM10 prism being the same as the OM1/2. |
