Ian - going back a bit - you seem to be hung up on this quote above.
Originally Posted by Ian Grant
I read that as when Agfa used hydroxide in the preparation, they were able to use high quality hydroxide. Poorer quality hydroxides would certainly contain carbonate. And hydroxide that sits around with exposure to air will sequester carbonate. So it could be both a manufacturing and storage issue when compared to earlier sources of hydroxide.
So I take their statement as one that means they were able to manufacture the hydroxide with very little carbonate content - not that carbonate was used at any point in the process or from any other ingredients. I don't think that statement has anything to do with preparation from free base.
Perhaps they were using sealed reaction vessels and perhaps they had nitrogen atmospheres to protect the hydroxide solution from atmospheric carbon dioxide. It would denote a couple steps up in manufacturing technology from years previous.
Bill - are you saying you are suprised that a 3% solution of potassium hydroxide has a pH of 14? If so, here's the way to calculate it.
Originally Posted by billtroop
A 3% solution is about 0.53M KOH.
Calculate pOH first:
pOH = -log10[OH-]
pOH = -log10[0.53M]
pOH = 0.276
Then calculate pH:
pH = 14 - pOH
pH = 14 - 0.276
pH = 13.72
A 0.53M KOH solution should have a pH of about 13.7. That's close enough to pH 14 for my book.
If that's not what you are saying, then don't worry, it's my mistake...
We have to remember that Agfa's parent company was already a highly sophisticated chemical manufacturer by 1897 so it's likely that they had a high degree of control over the purity of chemicals like hydroxides used in developers.
Originally Posted by Kirk Keyes
Reading work by contemporaries of Andresen working with similar developing agents they were aware of the differences between the free base & different salts of compounds like p-Aminophenol.
Mees & Sheppard did work with p-Aminophenol back in their days at Wratten & Wainwright, how much I don't know without trying to find copies of the book and papers they wrote (while at Wratten). This work is held somewhere along with the work of J.Desaume in Kodak archives.
Kodak also researched p-Aminophenol, Sheppard's name crops up again and their choice of salt was p-Aminophenol Oxalate (Kodelon) which presumably what they used in Kodinol.
George Brown, the Editor of the BJP from 1904 until 1934 would also have been well aware of the differences between the free base & the hydrochloride, (he was himself a Chemistry Scholar) he would have known Mees & Sheppard, he lists their Wratten Formulae in the 1910 BJP Almanac and makes a point of listing a concentrated p-Aminophenol developer, alongside a p-Aminophenol Hydrochloride developer.
What's perhaps more important is we know that by the 40's and through to today Agfa/A&O and Calbe have definitely used the free base, so any attempt at making our own needs to do the same.
Shows how much chemistry (& Biochemistry) I've forgotten, I'd just use a pH meter these days :D
Originally Posted by Kirk Keyes
As a historical side note: there was no `parent company´. Rather Agfa was a chemical company mainly producing dyes, that gave a try on producing a photochemical product (a film developer by Andresen) in 1889. That date given by Ian, 1897, was the introduction as brand name of their abbreviated company name.
Even when Agfa started to build their film manufacturing plant in Wolfen the sales of their photochemical products was about 9%. Even in 1923 it was only 36%. The photochemical branch (department from 1891 on) was not independant.
Agfa as a whole ended their independance when they opted to become a part of IG Farben.
Good point, but it would have been a division, and it's the Agfa brand name that we all know. In the US the company was the Berlin Aniline Works.
AGFA was the brand name for all products by "Actien-Gesellschaft für Anillin-Fabrikation". Though the consumer only new it at through their photographic products.
Would you be able to design an environmentally friendly Rodinal substitute? Paramidophenol is a verifiable water pollutant and injurious to health.
p-Aminophenol is far more widely used in hair dyes and in far larger quantities than the volumes of Rodinal used.
The actual amount of p-Aminophenol, sulphite and hydroxide used per film is likely to be far less polluting than most more concentrated developers (at working strength), somewhere I have the Toxicology figures for Colour processing because I had to deal with the regulatory authorities, in the UK there it is the water boards, because they have to treat the water and make it fit for human consumption.
In an average household there are far worse pollutants disposed of in a normal week.
Even a developer like Xtol used 1+1 is far worse than dilute Rodinal, so coming up with something more environmentally friendly is going to be difficult.
fyi- I've had to edit some bickering out of this thread and get it back on topic.