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)