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


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:


Potassium Bromide


Function to toughen the gelatin base to help minimise reticulation,
Types used:

Sodium Sulphate


Function to harden the surface of gelatin thus increasing resistance to scratching
Types used:

Chrome Alum

© Phil Gee 1980