For what it's worth, I use TF-4 and do a total of six five
minute soaks, without HCA bath, and it passes the chemical
residual fixer test. The soaks are one print per tray, with a
complete dump and fill each 5 minutes. Randy
The residual hypo test; the HT-2 test for remaining
thiosulfate. That test to approach archival levels must
show NO stain.
Your method is not efficient. As the level of fixer in a print
declines the time needed for diffusion of the remaining portion
increases. Of course a concentration gradient is required if
the fixer is to move from paper and emulsion to the wash
water. The really minute levels of fixer left after a rinse,
hca, rinse, and first soak or two, do resist and are slow
to remove. The latter soaks are removing little more
than traces of what over decades could be
harmful levels of thiosulfate.
Even with the little water I use those residual amounts
of hypo diffuse slowly into a relatively large volume of water.
A concentration gradient is maintained. I think those that
use several same time soaks are concerned with the
loss of the concentration gradient and fear that
equilibrium or near is soon reached.
It could be I allow more time than necessary. I'm in no
hurry. My prints sit unmoved. I like them to be ready for
their last soak in late evening. That last soak has been
as much as 16 hours. I should also mention that my
method uses a very minimum of water. Dan