Barry Thornton's Two Bath Film Developer
Barry Thornton's two bath compensating film developer.
Recipe
Mix chemicals in the listed order. Make sure each chemical is completely dissolved before mixing the next one. Mix a pinch of the sodium sulfite before mixing the metol. Use distilled or deionized water for improved keeping properties of bath A.
Bath A
| Chemical | Amount |
|---|---|
| Water (50 °C) | 750 ml |
| Metol | 6.5 g |
| Sodium sulfite | 80 g |
| Water to make | 1000 ml |
Bath B
| Chemical | Amount |
|---|---|
| Water (50 °C) | 750 ml |
| Sodium metaborate (Kodalk) | 12 g |
| Water to make | 1000 ml |
Usage
Develop the film in bath A. Agitate bath A as during regular film development. Pour off the developer to its storage container. Develop the film in bath B. Agitate bath B five seconds per minute. Pour off the developer to its storage container. Stop and fix as usual.
Don't rinse between bath A and B and don't use any pre-wetting technique!
Starting development times at 20 °C:
| Film | EI | Time A | Time B |
|---|---|---|---|
| Ilford Pan F+ | 50 | 4:00 | 4:00 |
| Ilford FP4+ | 125 | 4:50 | 4:50 |
| Ilford HP5+ | 400 | 5:00 | 5:00 |
Comments
This developer yields relatively fine grain for the sharpness it produce. The tonality is similar to D-23 as this is a metol only developer. The capacity of 1 liter of part A and B is around 10 rolls of film. Keeping properties of part A is at least 6 months in a full bottle. Keeping properties of part B is much longer.
Part B only contains an alkali (accelerator) which develops left over developer from part A to completion. Shadows are developed more than highlights as they use up less developer. This is the mechanism that makes this a compensating developer.