Re: alkaline fixer TF-3

From: Sandy King <sanking@clemson.edu>
Subject: Re: alkaline fixer TF-3
Date: Fri, 04 Feb 2005 13:39:52 -0500

> 1. What in particular is it about the TF-3 formula that makes you not
> recommend it? The pH of a working solution of TF-3 is around 9.0. Do
> you see that as a problem?

Unless you have a specific reason that requires that level of pH,
that's excessive. pH of 7 to 8 is high enough for rapid washing of the
fixer out of the emulsion, sizing and the paper substrate, but low
enough not to have excessive ammonia smell.

> 2.Would I be correct to assume that one could prepare a concentrated
> stock solution of the formula you provide below and dilute it for the
> working solution, as is done with the TF-3 forumla. If so, what
> strength stock solution and what dilutions would you recommend for
> film and paper?

I use that fixer for film, plates and paper. I personally don't make
concentrate of this fixer, but I suppose you can try. As long as the
solids dissolve, it should be ok. A 5x concentrate is maximum because
ammonium thiosulfate is usually supplied as 60%. I personally mix a
couple of gallons at a time and store them in jugs under the sink.

If permanence of the prints are important to you, there is no
substitute for doing basic quality control tests in your darkroom with
the same materials and washing water during each
shift/session. However, in MY darkroom in downtown Boston, using
municipal Boston tap water, baryta prints fixed in my fixer seem to
lose residual thiosulfate to well below 10 micrograms per square meter
within 30 minutes of washing without using washing aid. With washing
aid the time is shorter.

--
Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)