In a previous post – you can see it here – I mentioned Dr. Pratt’s developer in passing. A web search for it yields no results. I’d like to give the formula and instructions for its use here, so that it becomes part of the collective cyber-consciousness.
Dr. Pratt’s developer is a two-solution paper developer used to achieve different contrast levels with non-variable contrast papers. I got this information from Pirkle Jones in 1988.
The first solution, called Part A, or the soft solution, is made by mixing together the following:
- Water – 3 L
- Metol – 50 g
- Sodium sulfite – 180 g
- Sodium carbonate – 120 g
- Potassium bromide – 7 1/2 g
After you mix everything up, add water to make 4 liters.
The second solution, called Part B, or the contrasty solution, is made by mixing together the following:
- Water – 3 L
- Hydroquinone – 50 g
- Sodium sulfite – 180 g
- Sodium carbonate – 330 g
- Potassium bromide – 30 g
After you mix everything up, add water to make 4 liters.
Starting with number two paper, here are the mixtures to get approximate paper grades between one and four:
- 1 – 8 parts A, no B, 8 parts water
- 1 1/2 – 7 parts A, 1 part B, 8 parts water
- 2 – 6 parts A, 2 parts B, 8 parts water
- 2 1/2 – 5 parts A, 3 parts B, 8 parts water
- 3 – 4 parts A, 4 parts B, 8 parts water
- 3 1/2 – 3 parts A, 5 parts B, 8 parts water
- 4 – 2 parts A, 14 parts B, no water
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