Re: Fixing of a kallitype

On Sat, 13 Dec 2003, Sandy King wrote:

> 4. Because of the fact that the silver salts are on the surface of
> the paper, rather than embedded in a gelatin solution as in
> contemporary silver gelatin papers, the fixing solution reaches these
> salts immediately without having to pass through gelatin. For this
> reason fixer for kallitype can be weaker than what is typically used
> for silver gelatin papers, and fixing times can be much shorter.
>
> 5.Don't anguish over discrepancies and inconsistencies in the
> literature. Everybody could be wrong so make your own tests for
> residual silver nitrate and residual hypo in the print. If your tests
> don't find any residual hypo or silver nitrate I think it is safe to
> assume that your processing technique is sound. If you do find
> residual hypo or silver nitrate back to the drawing board.

Knowing Sandy I will assume that his answers are not only as well figured
as mine, but better and more closely systemized... But I will point out a
few things to Erich, who may perhaps have been brainwashed by standard, or
"factory" processes and "kits" into thinking there is one right answer for
every situation. This way lies continuing error and frustration when you
are using a home-mixed emulsion, on whatever paper from very thin & hard-
surfaced to nearly blotter-like, with chemicals of varying origin, purity
and age, coated in your own idiosyncratic manner, exposed according to the
whim of your electricity or sunspots, and of course washed in your local
water by your own methods.

Clearly there can be no one perfect answer across the board, tho I will
share the way I found AN answer for myself and students. I decided, first
of all that I DIDN'T want bleaching back, or as little as possible. (Most
sources assume you will have it, but don't say how much.)

I made about 100 strips exposed by 21 step, then ran the fix through 3
variables -- the strength of the fixer, the length of the fixing, and
amount/type of alkali. (But this was on a single-ply kid finish
strathmore, a softer heavier paper might well have been different.)

I found, not suprisingly, that strength times time is more or less
constant. That is, if you use a stronger fix, and bleach a shorter time,
the results will be the same as if you bleach a longer time with a weaker
fix. (I tested -- this from memory -- from 30 second fix to 3 minutes.)

My final choice was a balance of control and convenience... I picked the
shortest one I felt could be timed conveniently -- after all, a big print
won't get under the fixer solution all in the same second.

But 2 caveats: Don't judge from the wet or even the newly dried test.
There is a HUGE amount of drydown in VDB, and you can't choose til you've
seen that.I'd say it's a week before the color totally stabilizes. (These
tests were on untoned prints. Prints toned pre-fix would I assume be
different.)

And, of course, the print is being rocked in the tray THE ENTIRE FIXING
TIME. I guess I should have put that up top.

And yes, I did an HT2 Residual Hypo test -- in fact the whole class did.

PS. I don't know the chemistry of it, but my understanding is that the
alkali inhibits the bleaching back effect, but probably is not part of the
sdolublilizing done by the sodium thiosulfate... Here I am however over my
head, or at least over my memory. Maybe someone else will address that.

cheers,

Judy
Received on Sat Dec 13 15:42:37 2003