[pure-silver] Re: Cleaning a Drum Dryer
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 3 Apr 2007 16:35:03 -0700
----- Original Message -----
From: "BOB KISS" <bobkiss@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, April 03, 2007 6:12 AM
Subject: [pure-silver] Re: Cleaning a Drum Dryer
DEAR RICHARD,
I believe the baryta (barium sulfate) coating is under the
gelatin
layers and not suspended in them (Neblette, Mees & James).
Recently I tried
etching out a black spot in a print with a sharp tool
instead of bleaching
it out (or spotting the neg) and was a little over
enthusiastic. I saw the
image/gelatin layer(s?) come off and found the nice
powdery white layer
underneath. Good thing I had more prints!
CHEERS!
BOB
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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