RE: Daguerreotype base-metals - More

There is another, older way to deposit silver on glass. It was originally
used to make mirrors.
I cannot give you the formula but it should not be to hard to find. I
believe it is called the Brasheer
(sp?) process. The only problem with it seems to be that if the chemicals
are left standing around there is a tendency for fulminate of silver to be
formed which is, of course, very explosive and very sensitive. Thus is some
of the early mirror-making plants there were disasterous explosions. I think
I have an old telescopoe making book that has a formula in it, but I'm sure
a research librarian could find the formula. Vacuum depositin is now used
to "silver" front surface mirrors but that requires a pretty good vacuum
system and , if you have every worked with a vacuum system you know that,
according to one of my old physics professors, "A vacuum is a hole in space
surrounded by profanity." By the way, silver has the highest albido of any
known surface. That means it reflects
a greater percentage of the light falling on its surface than any known
surface. I guess thats why it makes such sparkley jewelery. Also many modern
first surface mirror are coated with a beryllium-aluminium alloy instead of
silver because silver tarnishes. However, silver is still used but
over-coated with quartz.

Bob Schramm
Check out my web page at:

  http://www.SchrammStudio.com

>From: Gregory Popovitch <greg@gpy.com>
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: RE: Daguerreotype base-metals
>Date: Wed, 07 Apr 2004 21:53:47 -0400
>
> > I'd imagine too that the gold chloride gilding would help in the
> > prevention of oxidation.
>
>Maybe it helps a little, but sealing under glass is still
>necessary. Even after gilding the image is very fragile
>and easily scratched (though I have an old dag which is
>very scratch resistant! I don't know how they did that).
>
> > Silvered glass, eh? No polishing you say? Intriguing!
>
>Irwing Pobboravsky wrote about his experiences with vacuum
>deposited glass plates in the "Daguerrean annual" from the
>Daguerrean Society. Some problems are:
>
>- silver don't stick to glass very well, so he would first
> deposit chromium, then a mixture of chromium + silver, and
> finally pure silver. Even then the metal layer may come
> off when processing (gilding)
>
>- the silver layer is extremely thin, so plates can be used
> only once (no repolishing)
>
>gregory

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Received on Thu Apr 8 17:55:57 2004