Re: Modifying PMK for rotary use?

Date view Thread view Subject view Author view

From: Francesco Curcio (fcurcio@libero.it)
Date: 01/10/01-07:55:56 AM Z


Tox,

when Harald Leban in 1998 posted to the list his formula for ABC+ Pyro
(eventually slightly modified in Rollo Pyro formulation, as published
in The New Platinum Print), I also wanted to try it
without having to remix a new batch of my standard PMK
and possibly avoiding the shorter keeping time of the A solution
when mixed with Ascorbic Acid.
Therefore I decided to prepare a more convenient separated
C solution containing the Ascorbic Acid, Kbr and EDTA,
to be mixed on the spot with amounts of the standard
PMK A and B increased as needed to reach the concentration
asked for ABC+ or Rollo.
I eventually noticed that the presence of Ascorbic Acid
in this C solution shortened considerably its life,
so this is what I do, working fine for me
(4x5 FP4+ developed in rotary Jobo 2509 reel,
70F /21C, about 7'):

Mix 200 ml of C solution as below (keeps indefinitely):
Deionized Water 200 ml
KBr 0.5 g
EDTA 1.5 g

When wanting to prepare the developer, mix
on the spot a 1% fresh solution of Ascorbic Acid
(to be dumped after partial use):
Deionized Water 100 ml
Ascorbic Acid 1 g

Then, to mix 1000 ml of ABC+ working solution:
Deionized water 1000 ml
C solution 10 ml
Ascorbic Acid sol. 10 ml (=0.1 g of Ascorbic Acid)
Standard PMK A 25 ml
Standard PMK B 30 ml

In this way, in a liter of working solution you have:

Pyrogallol 2.5 g
Metol 0.25 g
Sodium Bisulfite 0.5 g
Sodium Metaborate 9 g
Ascorbic Acid 0.1 g
Potassium Bromide 0.025 g
EDTA 0.075 g

I have no general fog and a good stain (I also mix and
use TF-2 alcaline fixer), even if I suspect that a lesser
amount of KBr and Asc. Acid could be experimented
to get an ideal equilibrium between overall fog
and pyro stain, related to one's specific
working variables.

Francesco Curcio
Milano Italy

Tox Gunn wrote:
>Thanks. I also forgot about the bromide in the ABC+.
>Hm.
>Pondering soemthing along the lines of 3:2:100 PMK
>plus 0.10g Ascorbic and 0.025g EDTA.
>Hm.
>
>If I find an answer, I'll post it to the list,
>suspect there might be some value to a "C" solution
>for PMK that would bring it to "Rollo-imposter"..;)
>
>If I run short on time and test sheets, I may jsut
>go buy the Rollo kit.
>
>Thanks,
>Tox


Date view Thread view Subject view Author view

This archive was generated by hypermail 2b30 : 02/05/01-11:45:21 AM Z CST