[pure-silver] Re: Cleaning a Drum Dryer
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Tue, 3 Apr 2007 20:47:20 -0700
----- Original Message -----
From: "john stockdale" <j.sto@xxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, April 03, 2007 7:07 PM
Subject: [pure-silver] Re: Cleaning a Drum Dryer
I dry fibre prints in a flat bed dryer with the emulsion
facing the cloth,
i.e. not ferrotyping. Even without toning, I've noticed
miniscule fibres
from the cloth well and truly stuck to the emulsion. I use
the usual
sulphite/bisulphite wash aid. Am I correct in assuming that
a hardening
bath after the wash aid but before the main washing would
make the fibres
less likely to adhere?
John Stockdale
The buffering of the Sulfite-Bisulfate wash aid (Kodak
Hypo Clearing Agent) is supposed to adjust the pH of the
emulsion to a point where the hardening of the usual white
alum hardener is still effective but where the mordanting
effect the hardener has for the thiosulfate is broken. Using
an after hardener would undo part of the effect of the wash
aid. I think its better to use either a hardening fixing
bath or an auxilliary hardener before the wash aid
treatment.
The usual hardening fixing bath, especially "rapid"
fixer, will fix out the paper before the hardener has time
to work fully. This is one of the reasons for the very long
fixing times specified in old books (along with the
assumption that the fixer would be partially exausted).
Since even hardened gelatin is fairly soft I suspect the
real answer is to use some other method of drying or to
replace the aprons (if possible) with new ones that don't
leave fiber particles.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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