RE: Reversal processing for enlarged negatives

I tried sepia "redevelopment" a long time ago, when I first started
experimenting with reversal negs. It works in as much as it produced an
image, albeit of lower visual density than silver, but it was completely
opaque to UV, even in the shadows. It's so long now that I don't
remember whether anything else could have accounted for this, but what I
do remember is that the result wasn't any good for a printing-out
negative the one time I tried it.

But if anyone wants to try (or maybe make a brown negative bromide
print) there is a simpler way than reversal chemistry. Expose and
develop a positive, rinse in clean, plain water (do NOT use an acid
stop!), then put film/print into the sepia toner (use odourless sepia in
the darkroom, folks). The light can go on now and on a paper print
you'll find a black image on a greenish-brown background, and the whole
thing will be very dark. Wash it (no need to fix) and then put into a
(preferably strongish) ferricyanide-bromide or similar bleach until the
black positive is bleached, revealing a brown negative. Wash and fix to
remove the halide "residue" of the black positive. (I guess that you
could also use a reversal bleach and do away with the fix.)

I don't remember exactly, but I think overexposure of around 2 stops is
needed to get a negative with full tonal range. I never tried this with
a flash exposure, which would affect the enlarger exposure time.

I also tried D-19 + thiocyanate for first development, as per Kodak's
insructions for reversal of Panatomic-X (for which D-19 without
thiocyanate was recommended for the 2nd. dev.) Again, the exact details
are a little hazy now, but I seem to recall that while thiocyanate made
a useful difference when reversing camera films, it didn't confer any
particular advantage on lith films. As a silver halide solvent,
thiocyanate assists in achieving clear shadows, but lith film is so
contrasty that it doesn't need this assistance as long as the exposure
and development time are adequate. And I also found that lith film gave
much better reversal negs than contone film.

Liam

-----Original Message-----
From: Ryuji Suzuki [mailto:rs@silvergrain.org]
Sent: 23 March 2004 22:39
To: alt-photo-process-l@sask.usask.ca; loris_medici@yahoo.com
Subject: Re: Reversal processing for enlarged negatives

From: Loris Medici <loris_medici@yahoo.com>
Subject: RE: Reversal processing for enlarged negatives (was Re: RES:
The Great Scanner debate - round one)
Date: Tue, 23 Mar 2004 15:38:52 +0200

> Sorry, I have stated wrong dimensions (twice!) - guess I was very
> sleepy last night. The exact dimensions are 50cm x 30m (20" x 100')
> and I finally decided to have it cutted to 25cm x 30cm size (10" x
> 12", I just ordered an 11" x 14" contact print frame from B&S) -
> this will make ~ 200 sheets with no waste at all.

What is that film called?
(Umm... I guess I don't need a distraction here...)

> Ok, you say that D19 formula + 2g/L potassium thiocyanate is good for
> optimum first development. Then what should be the development time?
> Should I use this developer in stock strenght? BTW Is the formula
> metioned @
> /lists/alt-photo-process/2001/aug01/msg00424.html
> Ok? (Elon is Metol I presume...)

That's right, though you can buy D-19 in packaged form from Kodak. If
this is too much trouble, Dektol stock strength isn't bad either. Use it
at stock strength with 2g/L of thiocyanate, and development should be
done to completion like development of prints. If you see any problem,
cut down on thiocyanate.

> > 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
>
> I didn't understand this... 1) Why should I want to flash from the
> back side? 2) What if I use light from an enlarger with condenser
> head?

Graphic art materials tend to have dye to reduce light scattering in the
coated layer. If you flash from one side with highly directional light,
you might be fogging the crystals near the surface, but not the ones
behind them. The purpose of flashing is to reduce overall density of the
reverse developed film, but you want to expose all big crystals if you
want to minimize granularity of the resulting film. Putting a tracing
paper just above the film and move it around during flashing also may or
may not help.

If your film is very thin coated without dye, you'll notice little
difference, but it's worth trying a few times before deciding.

> Well, I have only access to standard Ilford Ilfostop or Kodak
> Indicator Stop Bath (both w/indicator dye). What would be your
> comments for these?

Umm... no one sends me sample products so I can only tell you about
stuff I've used... but MSDS indicates that neither of them is buffered.

But think about it. If you are contact printing, you won't see pinholes
even if they occur. So you can just do that. But if you want to do
something about it, you can add NaOH or carbonate slowly, until the
slightest color change is observed. That's about pH of 5.2 to 5.3.
(Both of those products use bromocresol purple as the pH indicating
dye.) If the stop bath turns to purple color, you can revive the stop
bath by adding more of the Ilford or Kodak concentrate solution, or you
can add plain acetic acid until the color is just back to yellow.

> I also didn't understand this - using toners as second developers? You

> say if I "develop" - in safelight conditions - in Selenium or Sepia
> toner then I don't need to re-expose the bleached film? What should be

> the dilution for Kodak Rapid Selenium Toner? I have powder thiourea,
> how I can make "alkaline thiourea" toner using it? What would be the
> "development" timing for each toner?

That's right, and KRST 1+9 or 1+19 should work.

The purpose of redevelopment is to convert all the remaining silver
halide crystals into silver or silver compounds that are stable and
build optical density. If you can fog all the crystals either optically
or chemically, then any print developer should do (for this purpose, I'd
use Dektol 1+1 or 1+3).

But all these are unnecessary if you use KRST, brown or sepia toner.
These toners convert silver halide crystals to silver selenide/sulfide
independent of whether the crystals have been exposed or not.

You can make a non-smelly sepia toning bath by mixing 5g/L of thiourea
and 5g/L of NaOH. This is commonly found in darkroom literature. (If you
brown tone finished silver gelatin prints, you'll have to bleach the
print in ferricyanide (formal name: hexacyanoferrate (III)) bleach,
rinse and immerse in this bath. But I don't like that color.
selenium-polysulfide combination is much better to my taste. The image
hue shouldn't affect your purpose because you're using these films for
contact printing.

> Ok, it seems that I've confused it with sodium bisulfite. I had read
> this: http://silvergrain.org/Photo-Tech/chemistry-misnomers.html once
> looking for other information and that caused my confusion (my fault).

Yeah bisulfite is unstable in dry form. But you can use metabisulfite
for all photographic purposes.

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