Ilford Perceptol

About the Developer

Ilford’s Perceptol is, in terms of composition and philosophy, a close relative of the Soviet D-25: it uses the same metol as the sole developing agent and contains no active alkali. Opinions about it vary: some photographers consider it the only ultra-fine-grain equalizing developer, while others prefer D-25 or D-23. The sodium chloride in the formula must be chemically pure—ordinary table salt is contaminated with magnesium and calcium salts and sulfates, which are harmful to the emulsion; potassium chloride can be used instead in an equimolar amount. Sodium tripolyphosphate does more than just soften the water here; it also gives the solution a slightly alkaline environment—without it, the developer will not work, so it cannot be omitted.

Character

A fine-grain developer. Produces very smooth negatives at the expense of some effective sensitivity. Flexible tonal range, subdued contrast. Not suitable for push processing.

Best films

Ilford Pan F+, FP4+, Delta 100 Professional, Kodak T-Max 100, ADOX CHS 100 II, Fomapan 100, Kentmere 100 — portrait and studio photography, where maximum grain smoothness is essential.

How to Prepare and Use

1. 1Pour about 750 ml of warm water (~45°C) into a 1-liter container and dissolve a small amount of sodium sulfite (about 10 g) in it.
2. 2After the sulfite has dissolved, add the metol and dissolve it completely.
3. 3Add the remaining sodium sulfite, followed by sodium tripolyphosphate and sodium chloride—add each subsequent substance only after the previous one has completely dissolved.
4. 4Let the developer cool to room temperature, then bring the volume of the solution up to 1 liter.
5. 5If necessary, filter the prepared developer.

Film Development Times (Official Ilford Data)

The time is the starting point at 20°C, according to the official Ilford data sheet “Perceptol, ID-11, and Microphen Film Developers” (2024). For films from other manufacturers, use these values as a guide and verify them with a test strip.