[pure-silver] Re: Cleaning a Drum Dryer
- From: Bogdan Karasek <bkarasek@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 03 Apr 2007 21:10:15 -0400
Hi,
When I was doing the sepia toning, it was written on the instructions
that a hardener should be used after toning because the bleaching
process renders the paper soft. Do they mean that the bleach "eats"
away the protective layer of gelatin coating in order to get at the
emulsion?????
I did not use a hardener and noticed that on several of my prints, there
were motes of dust imbedded in the paper. I took one print and tried
to rub off the dust but to no avail. That's when I realized that it was
imbedded in the paper, but which layer, emulsion layer or was there
still some gelatin left, despite the bleaching?
Cheers,
Bogdan
Richard Knoppow wrote:
snip
The Baryta layer _is_ a coating of gelatin. It is the sizing for the
paper. Most papers have more than one layer but the number of layers
also has to do with what sort of texture the paper is to have. Note that
there is a difference between texture and surface: texture is gotten by
callendering the paper before the emulsion is coated and texture is
usually from something in the overcoating (like talc).
Generally fiber paper has three basic coatings: the baryta layer, the
emulsion coated over this, and a protective layer of gelatin coated over
the emulsion. This protective layer is what is used to obtain the very
smooth surface when ferrotyping.
Dave Valvo, who is on this list, is a former Kodak paper expert and
can unboubtedly provide more complete information.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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--
________________________________________________________________
Bogdan Karasek
Montréal, Québec bogdan@xxxxxxxxxxxxxxx
Canada www.bogdanphoto.com
"I photograph my reality"
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