From: Liam Lawless (liam.lawless@blueyonder.co.uk)
Date: 12/03/02-05:40:24 PM Z
>From Clerc, re. kallitype:
"Soluble ferric oxalate is reduced to the insoluble ferrous oxalate by the
action of light. The latter salt id a powerful reducing agent but, by
reason of its insolubility, it is unable to reduce silver salts unless a
solvent of this salt is added in the form, for example, of a concentrated
solution of alkali oxalates or tartrates."
I'm not too familiar with kallitype, but something similar is probably going
on with VDB, where hypo is the solvent for a ferrous iron salt produced by
UV exposure. That would account for the darkening seen in the fix.
And I concur with Judy on washing VDB. Most instructions I've seen say to
give only a minute or so, but longer definitely enriches the image. 5
minutes or more gave the best results in my tests.
Liam
-----Original Message-----
From: rurmonas@senet.com.au [mailto:rurmonas@senet.com.au]
Sent: 04 December 2002 09:32
To: alt-photo-process-l@sask.usask.ca
Subject: RE: toning VDB & kalli - 2 questions
Quoting Judy Seigel <jseigel@panix.com>:
> Several of my students had very interesting results with a variable test
> on length of wash -- in EVERY case longer washing before fixing VDB (up to
> 5 minutes, instead of the rinse until no more milky water I was taught)
> gave stronger richer brighter prints. I don't know what if any bearing
> that has on the question of action of the fixer, but it does bear on
> printing.
I was thinking about doing tests with a wash time of 1, 2, 5, and 10 min
so that if fixing was not required, I could at least give a starting figure
for wash duration.
Richard
--- Richard Urmonas rurmonas@senet.com.au ------------------------------------------------- This mail sent through SE Net Webmail http://webmail.senet.com.au
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