Thanks for the backstory, I will probably have to do it someday.
_________________________________
John Hermanson
Camtech, Olympus OM Service since 1977
631-424-2121 www.zuiko.com
Call Olympus for FREE manuals!
1-800-221-3000
_________________________________
----- Original Message -----
From: "Joe Gwinn" <joegwinn@xxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Friday, December 21, 2001 11:52 AM
Subject: [OM] Re-silvering old pentaprisms
> There has been some discussion of how to deal with pentaprisms with
damaged silvering. It appears that there are no more spare prisms
available.
>
> I would comment that if the glass is undamaged, which is likely the case,
it's easy to strip the silvering and re-silver a prism.
>
> Stripping: Simply immerse the prism in Nitric Acid until clean. This is
the standard approach, and will strip the paint and the silvering, and will
not harm the glass.
>
> Resilvering. There are two approaches, true silvering and aluminizing.
It's likely that the pentaprisms are aluminized, not silvered, but for
repair either approach will work. Protect surfaces not to be silvered with
varnish, which is later removed by soaking in acetone.
>
>
> Silvering. With metallic silver deposited from solution, the traditional
silvering process. This can be done one prism at a time in one's kitchen or
basement using "Brashear's process", and is documented in many places, such
as in 1960's editions of The Handbook of Chemistry and Physics, and old
books on making telescopes. I don't recall the details, but Silver Nitrate
and Nitric Acid are involved. The process is quite simple and robust, but
absolutely clean surfaces are required. Thus the use of Nitric Acid to
clean the glass.
>
> More recent books omit chemical silvering processes, because vacuum
aluminization pretty well displaced all use of silvering.
>
>
> Aluminizing. One sends the optical goods off to a company that does it
for you, unless you have enough aluminizing work to do to make purchase of
the equipment worthwhile. Amateur telescope makers (ATMs) make their own
mirrors, and then send the mirrors off to be aluminized. Look in the back
of magazines like "Sky & Telescope" for the ads. There are probably
newsgroups and reflectors for ATMs. Some ATM books have the receipe for
silvering as well.
>
> It's cheapest to have a bunch of prisms metallized at once. It isn't
terribly expensive in any case.
>
>
> Back paint. Whichever kind of metal is chosen, especially if it's silver,
it must be protected with a coat of black paint. Suitable paints are sold
to Glass & Mirror shops. If one has aluminizing done commercially, one can
have the coater do the painting as well.
>
>
> Anyway, don't throw those old prisms out. Collect them and re-silver
them.
>
>
> Joe Gwinn
>
> < This message was delivered via the Olympus Mailing List >
> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
>
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|