Indirect toning with KRST

I didn't think it would work, but tried a few drops of undiluted KRST on
unexposed chlorobromide paper (but working under a strong light) last
night. After 5 minutes, nothing had happened and the experiment went in
the bin.

Tonight, however, I tried a different chlorobromide, with undiluted
KRST, KRST diluted 1+5, and plain tap water as a control. Water did
nothing, but KRST had started to do something after a couple of minutes
and after 10 mins. the undiluted KRST had produced a faint brown, but
the density was too low to be useful for anything much except maybe a
soft, low-density portrait. Diluted KRST, though still slow-acting,
gave a considerably darker brown in the same time. But the diluted KRST
had become dirty-looking with an extremely fine black precipitate that
looks just like selenium powder. I remember discussing this with a
chemist during my long-ago toning experiments, and that is what he
thought it was.

The small amount of diluted KRST produced a brown-black tone that is
much weaker than a developer would have produced, and I suspect that
this precipitation is exhausting the solution quite quickly; probably a
darker tone would be obtained by replacing the solution or using a
greater volume in the first place, but, to be honest, I don't think
selenium redevelopment would be very effective in reversal. (Allowed
enough time - 30 minutes plus - undiluted KRST does eventually produce a
darker tone than diluted.)

This little test reminded me of my earlier toning tests, which I
couldn't quite recall yesterday. What I was doing back then was
bleaching a print (don't remember which bleach, but probably ordinary
ferricyanide-bromide), and then toning in selenium. I was using not
KRST, but a home-made version from a published Kodak recipe; T-55, T-56
or whatever the hell it was, it contained selenium, ammonium chloride
and sodium sulphite, and involved boiling for a couple of hours.
Anyway, what I found then was that it did tone, giving soft brown images
with "diffuse" edges, but the toner put down a copious black precipitate
and exhausted very quickly; it was necessary to use a large volume and
replace it two or three times to get a satisfactory print tone. One
reason I used to make my own toner! Oh, and staining was difficult to
avoid, with shadows bleeding into highlight areas and all the black
powder floating around. Perfect results were rare, but they could be
quite nice!

Liam
Received on Thu Mar 25 20:52:21 2004