Perceptol film developer

Description

An extra-fine-grain developer: where D-76 gives fine grain, Perceptol gives grain you have to look for. The price is about a stop of film speed, and that is the terms of the deal rather than a side effect.

How it works

A high concentration of sodium sulphite acts as a silver solvent, etching the crystal edges harder than an ordinary developer does and smoothing the structure of the image. The same mechanism costs effective speed — part of the latent image dissolves along with the grain. So ISO 400 film is shot at 200 under Perceptol, and ISO 100 at 50.

When it earns its place

Where the negative will be enlarged hard: 35 mm to a big print, copy work, slow film on a tripod. Where speed or edge sharpness matters more, D-76 or Rodinal is the better choice — Perceptol trades one deliberately for the other.

Questions and answers

Do I have to rate the film slower?

Yes, or the shadows will be empty. About a stop; take the exact correction from the film maker’s chart.

Why is the yield lower than D-76’s?

Perceptol is used at stock strength rather than diluted, and each roll exhausts it more. The yield in the name is for undiluted use.