Re: [Rollei] MIrrors and Re-Silvering

["Richard Knoppow" <dickburk >]

- ----- Original Message -----
From: "Kotsinadelis, Peter (Peter)" <peterk  >
To: <rollei  
Sent: Friday, April 04, 2003 3:42 PM
Subject: [Rollei] MIrrors and Re-Silvering


>
>
> Is the mirror in a Rollei front silvered? Does the age of
the TLR have
> any bearing on the mirror type?
> Who can resilver this type of mirror (providing it is)?
> Thanks.
>
> Peter K
>
>
  Front silvering or first-surface mirrors are used where
the double reflection of a back or second surface mirror is
undesirable. We learn to ignore the second reflection in
ordinary mirrors but it would show up as a some what out of
focus ghost image in a mirror finder.
  First surface mirrors made with deposited aluminum are
quite rugged since the aluminum does not tarnish. Silver,
however, is quite sensitive to all sorts of oxidants in the
atmosphere and will dull fairly quickly unless protected by
a layer of lacquer. The lacquer may yellow but will continue
to protect the silver unless its disrupted.
  Silver has a slightly higher reflectivity of visible light
than aluminum when fresh but the reflectivity drops as it
becomes tarnished. Aluminum coated with similar materials to
those used for lens coatings has a higher reflectivity than
either uncoated aluminum or silver.
  Re-silvering can be done at home. There are several
methods. I think instructions may even be on the web. Some
methods require the use of Mercury. Those should be avoided.
  Rollei mirrors seem to be relatively resistant to damage,
perhaps because they are protected in a closed compartment.
- ---
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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