Developer - What is it?
It's a solution with water as the solvent consisting of:
Reducing Agents
Function to convert the latent image contained in the exposed silver halide crystals into metallic silver.
Types used:
High Energy - Hydroquinone - Microphen
Low Energy - Metol - IDII, D76,- Phenidone - Perceptol
MQ developer - Metol & Hydroquinone
PQ developer - Phenidone & Hydroquinone
Accelerators ( Alkaline)
Fast working - function to increase rate of development.
Types used:
Sodium Hydroxide - ph 12+
Sodium Carbonate - ph 11.5
Sodium Metaborate - ph 10.8
Borax - ph 9.6
Slow working
Sodium Sulphate
Anti - Oxidants
Function to reduce the rate of decomposition of the developer due to contact with the air.
Types used :
Sodium Sulphite
NB it can also inhibit the growth of large grains as it tends to dissolve grains slightly
Restrainers
Function to reduce chemically induced fogging.
The presence of metalic silver crystals can trigger developmet of adjcnet unexposed silver haylide crystals ( infectious development)
Types used:
Benzotriazonle
Potassium Bromide
Tougheners
Function to toughen the gelatin base to help minimise reticulation,
Types used:
Sodium Sulphate
Hardeners
Function to harden the surface of gelatin thus increasing resistance to scratching
Types used:
Chrome Alum
© Phil Gee 1980