[pure-silver] Re: Paperdeveloper for roller transport machine...contamination
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 22 Apr 2007 13:42:59 -0700
----- Original Message -----
From: "Claudio Bonavolta" <claudio@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, April 22, 2007 7:42 AM
Subject: [pure-silver] Re: Paperdeveloper for roller
transport machine...contamination
----- Message d'origine -----
De: "Dave Valvo" <dvalvo@xxxxxxxxxxxxxxxx>
Date: Sun, 22 Apr 2007 10:17:12 -0400
Sujet: [pure-silver] Re: Paperdeveloper for roller transport
machine...contamination
À: <pure-silver@xxxxxxxxxxxxx>
I just looked at this thread. RC paper does soak in
chemicals from the edges. It is called "edge
penetration". Some papers are worse than others depending
on the paper design. The deeper the processor, the greater
the pressure is from the chemicals and the greater the edge
penetration. Then the squeezing of the rollers acts as a
pump when pressure is released. RC papers if incubated
will show yellow edges that rarely go beyond 1/4 inch. SO
if you are concerned about edge penetration cut a quarter
inch off the sides. BTW, Kodak had technology that
prevented this from happening.
You can NOT wash the paper to remove this.
Dave
Dear Dave,
Do you know what's the impact of the residual fixer in the
paper layer of an RC print ?
Say, you overfix a RC print for an hour and then wash it
carefully to be sure the emulsion has a low level of fix in
it.
Will have the fix in the paper the possibility to impact the
emulsion layer through the plastic layer in-between or by
other ways ?
Thanks,
Claudio Bonavolta
http://www.bonavolta.ch
The question is whether anything in the paper layer can
migrate through the plastic to the emulsion. I suspect the
yellowing Dave mentioned is from decomposition of the
residual chemicals _in the paper_ layer rather than in the
emulsion, can Dave confirm this?
On another topic, there are a number of other problems
which RC paper proved to be vulnerable. One was the gas
emmissions from the TiO in the reflective layer, another was
decomposition and staining from residual developer in papers
with incorporated developer. Kodak, Agfa, and Ilford seem to
have found ways to cure all of these but I wonder if some of
the smaller companies currently making RC have this
technology. One reason Kodak's leaving the paper
manufacturing field was such a disservice is that IMO Kodak
had the most advanced technology of all.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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