RE: Van Dyke washing

How about using acetic acid for VDB ?

Scott B. Weber
Associate Professor of Photography
Department of Fine Arts
Barry University
11300 NE 2nd Avenue
Miami Shores, Florida 33161
(305) 899 4922 

-----Original Message-----
From: Loris Medici [mailto:mail@loris.medici.name]
Sent: Wednesday, April 12, 2006 12:00 PM
To: alt-photo-process-l@usask.ca
Subject: RE: Van Dyke washing

Citric acid will dissolve the unexposed iron sensitizer very effectively - I
personally think it's the best tool for the job (that is: clearing the
Vandyke print).
 
Cyanotype and Vandyke images are very different (Cyanotype image forming
compound is Prussian Blue - don't remember the exact name of the compound -
whereas Vandyke image is formed by colloidal silver). That comment was made
about Cyanotype, not Vandyke.
 
Also, it doesn't matter if Citric Acid is harmful to the silver image "in
long term" since you will be washing it out of paper in subsequent
processing steps; 1) rinsing in water after clearing -> 2) toning (optional)
-> 3) fixing -> 4) final wash... in fact, you use it in the first step.
 
IIRC, that comment was made because there's the risk of citric acid molecule
(a small one) being trapped inside of the prussian blue molecule (a large
one). (The original comment is very Cyanotype specific.)
 
One of the conclusions of our last correspondence with Mike Ware was:
clearing in citric acid is good for Vandyke, Kallitype (and maybe
Argyrotype) because you can get rid of iron -> which will eventually fade
(oxidise) the silver image.
 
Hope this helps.
Regards,
Loris.
-----Original Message-----
From: redman [mailto:redman@elmet15.freeserve.co.uk]
Sent: 12 Nisan 2006 Çarşamba 18:34
To: alt-photo-process-l@usask.ca
Subject: Van Dyke washing
I have been away from the group and alternative photography for a while. I
am now geting back into the Van Dyke process. After some experimentation and
reading the various bits of advice from this group, I have settled on
Fabriano Artistico paper and two coats of sensitizer. This seems to produce
satisfactory results. But I am now in a quandary.
 
Recently, I note that both Loris and Joe recommend the use of Citric Acid in
the initial rinse bath. However, following Peter Marshall's link to a
Cyanotype website
(http://photography.about.com/library/weekly/aa061801d.htm)  I came across
the following statement :
 
"Since Prussian Blue is unstable in alkali, it is essential to keep the
water used to 'develop' the cyanotype at least slightly acid. As most tap
water is slightly alkaline, and you should add a few millilitres of dilute
hydrochloric acid (still sold in some hardware stores as 'muriatic acid') to
a bucketful to use. Other acids such as nitric acid can also be used, but it
is best to avoid oxidisable organic acids such as citric or tartaric acid,
which can later break down the image."
Does anyone know if the same advice re citric acid applies to Van Dyke ?
Bob Redman (UK)
           
                       
                
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Barry University - Miami Shores, FL (http://www.barry.edu)
Received on Wed Apr 12 15:34:02 2006