The DARKROOM COOKBOOK, Third Edition

Pyrogallol and Pyrocatechin 69
Tests show that the Pyrocat-A stock solution is stable in partially full bottles for up
to a year. If shelf life of longer than one year is desired, I recommend mixing Stock A in
glycol. Pyrocat-HD Stock Solution A, when mixed in propylene glycol, has a shelf life of
several years.
Stock Solution B has an indefi nite shelf life.
Mixing 1.0 liter of Pyrocat-HD Stock A Solution in Propylene Glycol
1. Weigh out all of the chemicals for Stock A.
2. Pre-heat 750.0 ml of propylene glycol to about 150F/65C in a water bath or on a
hot plate with stirring.
3. Add the pyrocatechin to the warm glycol and stir until dissolved. This should take
no more than about a minute.
4. Add the Phenidone and stir. This should dissolve completely in about a minute.
5. Add the bromide and sodium metabisulfi te to about 50.0 to 75.0 ml of hot distilled
water at about 125F/51C. Stir until completely dissolved, and then add this solution
to the propylene glycol solution.
6. Top off the solution with glycol to 1.0 liter.
Pyrocat-MC
Pyrocat-MC is a Pyrocat variant that I recommend primarily for rotary processing,
where it tends to give slightly greater acutance than Pyrocat-HD. It can only be mixed
with propylene glycol.
Mixing Directions for Pyrocat-MC Stock A
STOCK A
Propylene Glycol at 150F/65C, 750.0 ml
Pyrocatechin, 50.0 g
Metol, 2.5 g
Ascorbic Acid, 4.0 g
Start with about 8.0 ml of triethanolamine (TEA) at room temperature and a spoonful
of water. Now add 2.5 grams of metol and stir to make a slurry. This is eventually going to
make a liter but you can start in a 1/4-liter cup. After the slurry gets a little more fl uid, add
15.0 to 20.0 ml of some warm propylene glycol. Now you can transfer the metol slurry
to the 750.0 ml of warm propylene glycol and stir until dissolved. Now add 50.0 grams of
pyrocatechin and stir until dissolved. Add 4.0 grams of ascorbic acid and stir until dissolved.
Stock B is mixed the same as for Pyrocat-HD.
Pyrocat-HD and Pyrocat-MC kits can be purchased pre-mixed in propylene glycol
from Photographers’ Formulary. For detailed information on use, with development
times for some fi lms, go to www.photoformulary.com and download the following technical
information documents:
Pyrocat-HD In Glycol 01-5091
Pyrocat-MC in Glycol 01-5095