Rodinal, also known by it's original Agfa formula number R09 (Rezepte 9), has always been made using p-Aminophenol free base right from it's first being formulated, that has never changed. Agfa R10 a two part developer uses p-Aminophenol Hydrochlride.
Originally Posted by pinholer
Dr Momme Andresen (of Agfa) who discovered the developing agent p-Aminophenol and frormulated Rodinal published a one shot developer in the german publication "Agfa Photo-Handbuch" in the very early 1900's and while it's close it isn't Rodinal as it uses p-Aminophenol Hydrochloride. Agafa publications of the same era stress it uses the free base. This is a bit complex to make at home and wasn't then commercially available.
Modern Rodinal from Agfa contains a surfactant with anti-oxidant/anti-foggant properties, (these are in a 1930's German Patent). In addition the Agfa Rodinal made from the mid 1960's also contains Potassium Bromide.
There will be differences in how the early Andresen p-Amininohenol hydrochoride one shot developer your using works and Calbe's current RO9 and also Agfa's later new version sold now as adolux etc. Those differences may be subtle and harder to spot with many of todays emulsions, keeping properties may be quite different as well.
Todays films have a greater inherrent sharpness and fineness of grain which is less affected by choice of dveloper than in the past.