Since the Rodinal formulas have never been published, where did you get this information?A difference is the Calbe RO9 contains more p-Aminophenol and no excess Hydroxide while the later Agfa formula uses less p-Aminophenol at a higher pH and there is excess Hydroxide to give that pH increase which makes it more efficient.
Since the Rodinal formulas have never been published, where did you get this information?
- Leigh
OK. The Agfa MSDS that I have (225P.02 08/02/2002) has only general concentrations (e.g. p-Aminophenol 1%-5%).The two manufacturers have published quite accurate MSDS data over the years, these give things like the pH, amount of p--Aminophenol and sulphite.
The two manufacturers have published quite accurate MSDS data over the years, these give things like the pH, amount of p--Aminophenol and sulphite.
The Rodinal formula was published in a FIAT report after WWII and aside from one additive the figures all match up perfectly. The additive is an anti-oxidant/long chain wetting gaent which Agfa Patented before WWII. There's other data as well from reliable sources such as LP Clerc as well as Dr Andresen's own book where he published p-Aminophenol hydrochloride based developer formulae. Rodinal uses the free base which needed preparing first.
One of the Bayer as opposed to Agfa MSDS sheets for Rodinal gave rather accurate information, I don't think it was supposed to be generally available information as it gave orecise percentages to 0.1%. I've two versions of that MSDS sheet and the newer one is back to generalised percentages.
We know from Agfa's own books published first over 100 years ago that original Rodinal is a 5% solution of the p-Aninophenol free base in a strong sulphite solution with no excess hydroxide. In the early days the concentrated Sulphite solution was formed by adding Hydroxide to Metabisulphite and a characteristic of the original Rodinal and ORWO/Calbe R09 is the prescence of crystals of p-Aminiphenol free base which form when there's no excess hydroxide. This gives a pH of 11.8
Agfa reformulated Rodinal when they merged with Gevaert in the early 1960's they dropped the p-Aminophenol concentration to 4.1% and inceased the pH to 14 to compensate with additional Hydroxide.
Ian
There are slight variations, as I mentioned in my earlier posts. Its a personal preferences and it counts what film format you use and how You process it. Most folks who say they can not see differences between the versions are mostly Multi Format Shooters and if You add to that some of the all-time dark room variables, like., types of water, temperature accuracy, dev. tank designs, agitations, enlargers, papers...So what is the final verdict? I've loved Rodinal for years and I have one bottle left of it from the Agfa Photo days and 3 and 1/2 bottles of R09. I cannot tell the
difference.
There are slight variations, as I mentioned in my earlier posts. Its a personal preferences and it counts what film format you use and how You process it....................so, the only way is to try them all.
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