URGENT: You really should use a stop bath with film if you are using an acid
fixer. I started doing photo conservation/archiving work nearly 30 years ago
and enlisted the aid of Jose Orraca, a world famous photo conservator, a number
of photo historians, and the remaining synapses from my under grad and grad
photo chem from RIT. Something that kept showing up in older negatives was
dichroic fog. When asked, ALL my advisors said it resulted from the film going
from alkaline developers into acid hardening fixers without stop bath.
NOW: if you use a neutral or slightly alkaline fixer like TF-5 or most other
ammonium thiosulfate fixers, no prob. But alkaline dev to acid fixer, you have
probably cursed your negs to dichroic for in the future. Before digitization
and numerous redundant data storage systems, the negative was revered as "the"
document and the print as the artist's statement...Adams said, the negative is
the score, the print the performance.
I am sure that Richard will look into his extensive documentation and confirm
what I claim above...
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of MARK SAMPSON ;(Redacted
sender "msampson45" for DMARC)
Sent: Thursday, March 18, 2021 5:57 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: simple stop bath recipe?
Interesting. TF-5 is alkaline and non-hardening... the lack of which has not
caused any problems with the prints. I’ve been told that TF-5 is buffered and
doesn’t require a stop bath, a water rinse is good enough. I guess I’m being
traditional by using a stop bath.
I time the stop bath for the usual 30” and have not noticed any continued
development in the fixer. Never imagined such a thing could be possible- even
after 40+ years in the craft. Live and learn!
Mark S
Sent from my iPhone
On Mar 18, 2021, at 2:17 PM, Wilbert van den Berg <wilbert@xxxxxxxxxxxxxxx>
wrote:
15 gr of citric acid in 1 liter of water.
Le 18/03/2021 à 21:58, `Richard Knoppow a écrit :
Citric acid works fine where the fixer does not have alum hardener. It has
the virtue of not having a vinegar odor. Can also be used in non-hardening
fixing baths. Actually, fixers do not need to be acid, the fixing action is
independent of pH but they are made acid partly because the alum hardener needs
it and also to make sure any developer carried over is inactivated. A stop bath
will usually take care of the developer but the usual few second stop bath does
not wash out the developer which can become active again if put into an
alkaline bath.
--
wilbert@xxxxxxxxxxxxxxx
04 73 72 19 20
"Quand on se retrouve du côté de la majorité, il est temps de prendre du recul
et de réfléchir."
Mark Twain