Rodinal

General purpose film developer

Part A
Water 165F/75C150ml
p-Aminophenol Hydrochloride20g
Potassium Metabisulfite60g
Part B
Cold Water150ml
Sodium Hydroxide25g
Part C
Cold water to make1000ml
Mixing Instructions: Add chemicals in specified sequence. Always use cold water when mixing sodium hydroxide due to risk of heat reaction. Always wear gloves and protective goggles when mixing sodium hydroxide. Unlike many other two part developers you must mix both parts together to make the concentrated solution. Part A: Boil 150 ml of water allow to cool to 160-170F/70-75C pour into a thick glass or ceramic container. Add 1 gram of Potassium Metabisulfite stir until dissolved. Add the p-Aminophenol Hydrochloride stir until about 75% dissolved. Add the remainder of Potassium Metabisulfite complete mixing. Part B: Pour 150 ml of cold water into a a thick glass or ceramic container. Fill a large plastic pan with ice cold water for use as a water bath. Place the 150 ml container into the water bath. Add the Sodium Hydroxide stir until dissolved. Final Mix: Allow both solutions to cool to 125F/52C before continuing. Pour both solutions into a 1 gallon bottle. Cap tightly. Shake for 30-45 seconds over sink allow to settle. Shake for another 30 seconds until solution is cloudy. Add cold water to make 1000 ml. Filtering: Decant solution into 2x 500ml bottles. Allow solutions to settle for 48 hours until clear with dark precipitate at bottom. Filter each solution through a doubled-over paper towel into a suitable container. Rinse out each 500ml bottle then pour filtered solution back into bottles. Wait another 48 hours. Filter each solution using a coffee filter to remove smallest particles. Rinse out each 500ml bottle then pour filtered solution back into bottles.
Dilution: 1+25, 1+50, 1+75, 1+100
Usage: Starting point development time varies by dilution.

Notes 

The most recent commercial formula for Rodinal is unpublished, but it is known to contain Potassium Hydroxide instead of Sodium Hydroxide.

In The Film Developing Cookbook, Troop and Anchell list a much stronger formula for Rodinal. The formula published in The Film Developing Cookbook is not recommended for use and is disputed.

Mixing this formula is recommended for experienced users only.