The DARKROOM COOKBOOK, Third Edition

Pyrogallol and Pyrocatechin 63
A larger problem that has vexed pyro/cat users is aerial oxidation. Aerial oxidation results
in random and unwanted stains, mostly in areas of high density, which can ruin the negative.
1 The problem occurs because developers compounded with pyro/cat have a tendency
to rapidly oxidize as the developing agent becomes exhausted—in no small part because of
the minimal amount of preservative used to compound pyro/cat developers in order to produce
image stain. When a negative is exposed to oxygen, either by pulling it from a tray or
as the rotary drum of a JOBO processor goes around, an irreversible stain appears on any
area of the negative where the developing agent is exhausted—which is most often in the
highlight areas. The remedy is to use enough developer or developing agent in solution so
that it will not exhaust during the development cycle even in areas of high density. If traydeveloping
sheet fi lm, use a minimum of 1.0 liter of developer per 8 � 10 inch sheet of fi lm
in an 11 � 14 inch tray, or four 4 � 5 inch sheets in an 8 � 10 inch tray. This is a minimum
recommendation.
If using a JOBO rotary processor it is not possible to use this volume of developer
without burning out the motor. The simple remedy is to increase the amount of developing
agent in solution. Try adding 30% or more of Solution A than called for by the formula.
This will insure that the developing agent is not fully exhausted by the time the process is
complete.
A second solution is to use Harald Laban’s AB C� Pyro (available as Photographers’
Formulary Rollo Pyro). Adherents to Rollo Pyro claim that because of the use of ascorbic acid
(vitamin C) as a preservative and a large quantity of pyro, it does not oxidize like traditional
pyro formulas and can safely be used with JOBO rotary processing. Compared to other pyro/
cat developers, Rollo Pyro creates a light image stain.
The simplest remedy is to not use a rotary processor with pyro/cat development. While
JOBO rotary drum processors may work well for large format negatives souped in MQ and
PQ developers they are not ideal for developers that potentially ruin negatives when they are
exposed to air during routine development.
Two fi nal notes on development with pyro/cat: Despite what some photographers claim
for their formulas, pyro/cat formulas should not require vigorous agitation. If they do then
there is something seriously wrong with the formula and its use should be discontinued.
Agitation for pyro/cat developers should be the same as for any other developer: 2 continuous
for the fi rst minute; 10 seconds every minute thereafter with gentle inversions at the rate of
three to four per 10 seconds. If using a tray follow the same cycle: Agitate by lifting the corners
of the tray continuously for 60 seconds, allow the fi lm to sit in solution, then lift the corners
four times at the end of every minute (Chapter 4, Agitation).
One more problem associated with pyro/cat developers is their tendency to stain everything:
fi ngers, clothing, and work surfaces. If you experience a problem with this try using
one of the stain removing formulas in the Formulas: Miscellaneous section of the Cookbook.
1 Aerial oxidation stains can sometimes be removed with Kodak S-6 Stain Remover. However, it is better
to avoid stains in the fi rst place as this treatment is not always effective.
2 With the exception of divided developing formulas.