Re: Eastern European RC papers

From: fb <aikus2@freestart.hu>
Subject: Re: Eastern European RC papers
Date: Tue, 24 Jan 2006 10:40:53 +0100

> As I know the hardened gelatine a bit more sealing the
> silver contents against the humidity and air pollution.

I disagree...

Crosslinking of gelatin molecule has practically no effect on the dry
mechanical properties of the gelatin. The temperature profile of the
drying condition has far greater influence on this. Ideal condition is
to dry the plate (or film or paper) well below the gelling
point. Typically coated emulsion is chilled to set before drying for
this reason.

> In normal case to eliminate the bad effects of the base
> material is the task of the substrate and/or baryta layer
> (a seal problem again). Do You think that layer cannot
> handle this problem in a few products?

The problem with early generation RC is that the resin layer actively
generates agents that degrade image forming silver particles. It took
long time for AGFA, Kodak, Ilford, Fuji and others to figure out how
to fix this, and details of what they did are unpublished. So I don't
think this is an easy problem that companies with less experience with
RC can fix in a short period of time.

> I agree, but a practical aspect: You can control the
> process conditions include the level of fixer reminders
> if You minimalize it that type of risk will also
> minimalized.

Frankly, people here are serious enough that they should be running
basic quality control with silver nitrate test, methylene blue test or
moresophisticated methods in their own darkroom. Excessively high
level of residual thiosulfate and thionates is out of question and
unacceptable to me. I tone my prints and make sure prints are washed
to less than 10micrograms of thiosulfate per square meter.

But I must say that putting too much focus on control of residual
thiosulfate is misleading. In my view, toning of prints in polysulfide
and controlling humidity of the storage environment are much more
important than the difference it makes between 5 micrograms and 20
micrograms per square meter.

Another problem is that, many people store their prints in the box
with which the paper was packaged. THOSE BOXES ARE NOT ARCHIVAL!
Indeed, most cardboard materials are very skeptical in this regard.
Received on Wed Jan 25 03:01:24 2006