FerricOxaCitrate a different sensitizer ?

[Harald Leban]

Some of the old Ferric processes always used ferric salts of citric acid, mainly a Ammonia double salt for advanced solubility.

Knowing that with the FerricAmmonium-salt you always had a printing-out process!

When a developing-out process was needed, it was always that Ferric(III)oxalate was the sensitizer of choice. Nobody wanted to use Ferric(III)citrate because it´s low solubility in water (4g/l = 0,4% ) was useless for this purposes.



I was thinking about a possibility of creating a kind of Ferric(III)citrate like I make my own Ferric(III)Oxalate from Fe(II) salts in a simple reaction.

I make my sensitizer for Pt/Pd printing from Ferrous(II)oxalate +oxalic acid and oxidation through Nitric acid (HNO3)



I switched the formula to Ferrous(II)oxalate +citric acid and oxidation through Nitric acid and got a solution that I named FerricOxaCitrate.



I write this because this happend around 8 years ago but I didt had the time for extensive tests on pt/pd - I found the bottle in my freezer few weeks ago and wanted to throw it away but when I checked the mix it still looked clear and free of precipitation (never got Ferricoxalate solutions so stable).



For me it´s a good sign that this mixture must be very stable and maybe worth to try again for these old processes - remember, its a kind of pure Ferric(III)citrate.



More when I have checked it´s properties in printing.

[Paul Cunningham]

You've made me curious, any results?