Reversal processing for enlarged negatives (was Re: RES: The Great Scanner debate - round one)

From: Loris Medici <loris_medici@yahoo.com>
Subject: Re: RES: The Great Scanner debate  - round one
Date: Mon, 22 Mar 2004 09:24:45 -0800 (PST)

> Ryuji, the 24" x 30' roll of orto-litho film that I
> had ordered just arrived to the store. They will cut
> it to 20"x25" sheets for me - will have ~ 300 sheets.

Why do you waste 4cm at the end? Maybe this is just me, but I'd
rather keep that margin and don't use it, so that the risk of damage
to the image area is reduced. (Also I might want to cut it into
squares since I love square images.)

> What developer do you suggest that I use to get
> grain-free enlarged negatives with the smoothest
> continous tone? I will reversal process the film -
> according to the procedure described in Lawless /
> Buffaloe articles and I have some experience with this
> workflow... I have enlarged ~ 20 sheets with mixed
> results. My problem was unpleasant grain in the dense
> parts of the negatives. I'm using sulfuric acid /
> potassium dichromate bleach and sodium sulfite
> clearing bath.

Ok, I had to read that article and think a bit... but I have a few
recommendations that you can try (and mix and match whatever works for
you).

For the first developer, I'd suggest to use some of the cold tone
developers, but the classic choice would be D-19 with 2g/L or so of
potassium thiocyanate. Ilford ID-62 (is Bromophen ID-62? I don't
know.) stock strength would be good also, but thiocyanate addition
tends to make highlight area more brilliant. (They tested with Dektol
1+2, but if you use Dektol, D-72, D-19, ID-62, etc. stock strength is
better.) Also, if you dig darkroom literature, you'll find dozen
developers published for reversal processing. Since you don't care
about the speed of the reversal processed film, I think D-19 plus
thiocyanate is pretty close to optimum.

Incidentally, I don't think APH would make dichroic fog that easily,
but Kodalith will. If you see dichroic fog, it's ok as long as it goes
away in bleach and image sharpness is not compromised. If sharpness or
other problem persists, cut down on thiocyanate, and then sulfite. One
problem is that graphic art material comes in a very wide range of
flavor and each one of them has strong character. It's nothing like
comparing T-MAX and Tri-X.

When you flash the film, it may or may not be helpful to flash both
front and back sides with diffuse light. If the film has dense base or
good antihalation dye, back exposure would require much longer time. I
think the APH Lith film had antihalation dye in the back coat, but it
bleached when moistened with plain water, if I remember correctly. (I
think Kodalith needed sulfite bath to lose density of anti-halo
dye... but I'm on my third glass of Italian grape juice right now.)

They recommend water rinse and fresh plain acetic acid bath to reduce
pinhole and halt development. Unless you like to do extra work, I
recommend to use buffered acetic acid stop bath. If the bath is
buffered in the range 4.5 to 5.5, pinhole shouldn't be a problem.
This type of bath has a large processing capacity and arrests
development very rapidly. Sprint stop bath (forgot name... was it
BLOCK or something?) is such a product.

I'd bleach in safelight.

When washing bleach, make sure the tap water is on the alkaline side.
THis is not a problem in Boston area (tap water is pH of about 9.1)
but in some areas water is slightly acidic. (If you use permanganate
bleach, this is opposite and you want to be on the acidic side.)

Clearing should be done in sodium sulfite solution as instructed on
the web, but addition of some borax or even carbonate may be helpful
in clearing rapidly. Again, this is for dichromate bleach, and if you
use permanganate bleach, you want to use straight sodium metabisulfite
clearing bath to be on the acidic side.

They redevelop in developer with light on, but for enlarged negative
purposes, I'd recommend to use Kodak rapid selenium toner if you
prefer higher Dmax, or the toner part of sepia toner (either sodium
sulfide or alkaline thiourea works, but you can use Kodak brown toner,
or a couple of soybean size piece of liver of sulfur in a liter of
water works as well.) if you prefer lower Dmax, both with or without
room light. This method will result in more complete redevelopment of
the remaining silver halide. If the enlarged negative comes out too
dense (likely) because of more complete redevelopment, increase the
imagewise exposure, flash exposure, or both. THis might not be
preferrable in reversal processing of in-camera films because it would
make the nominal speed slower, but since you are enlarging negative,
this should not be a problem.

The idea is that, both imagewise projection exposure and flash
exposure make larger, more sensitive crystals developable. Powerful
developer develops most of these guys, and bleach will get rid of
those grainy guys. One problem is that, overall fog level in
highlight areas will be high, because small, less sensitive grains
won't be developed and removed, but those guys give rise to good
density (whereas big grains don't contribute to density as much).
Addition of thiocyanate in the first developer helps to dissolve some
of these tiny grains preferrentially in the high exposure area.

With ad hoc room light exposure and redevelopment in ordinary
developers, many of these tiny crystals aren't developed. So your
final image mostly consists of medium sized grains. But if you make
the redevelopment more complete (the easiest way is to use KRST or
sepia toner, as I said, but you can mix some fogging agents in the
developer as well. Indeed, a small amount of thiourea from non-smelly
sepia toner would work.) and recalibrate for the initial exposure
stages, so that big and medium grains are thrown away during bleaching
and you get to keep the small grains. You might think plenty of room
light should do it, but it's more likely incomplete exposure, partly
because sensitive sites on the silver halide crystals were destroyed by
the bleach, making tiny grains super slow.

If you redevelop in these toners, there is no need to fix because
there won't be anything that needs to be fixed. If you find your
material not hardened enough, I'd harden in or before the first
developer solution because this is where the coated layer gets soft. I
don't own a stock of a company who makes glutaraldehyde, but this is
clearly the best option here. Formaldehyde will not work because it
will react with sulfite in the developer.

However, some good graphic art films are made in such a way that grain
size is extremely uniform. I don't know how these work for this
application.

Anyway, the first developer, the way you flash expose the film, and
the way you redevelop are three major things I'd do differently from
that article.

> The sulfite is old (around 1 year) and
> was in a plastic bag (knotted mouth) - do you think it
> is still good? I remember it gets bad very quickly so
> what else I can use to clear the film?...

Sodium sulfite in dry form is stable, though once you dissolve in
water, I is just like developer solution and won't last long.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)