Re: Making Ferric Oxalate from Scratch
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Hi Mike, Niranjan,
In regards to lactate, some time ago I made some ferric ammonium lactate (FAL)using precipitated ferric hydrate. I first added ammonium carbonate to the lactic acid in the amount of 1/2 of that required to neutralize it to pH 7, then the hydrate was added and warmed and stirred til no more dissolved.
The final solution was yellow, had a speed typical of ferric ammonium citrate, but bites in better to the fibres much like the oxalate formulas, so you get a nice tonal gradation. It is less stable than the citrate, and PF+ FAL mixes do not keep for long going blue, so mix at time of use.
Here is the unusual outcome: The prints are deep but have a muted violet hue, leaning in the direction of a lead toned Cyanotype but less colour saturated with the densest regions almost black, very appealing to my eye. Now if this finished print is placed in bright light like sunlight, and the print is left to recover, the violet hue is lost and the colour reverts to amore traditional cyanotype hue.
FAL seems to be very hygroscopic, even more so than FAC and was wondering if the prussian blue formed is some type of hydrated form. I have seen violet hues show up on cyanotypes made with wet emulsions so maybe this is possible, and perhaps after the light exposure, it reverts to a more stable form upon re-oxidation...lots of conjecture!
On Nov 17, 2020, at 5:51 AM, mike@... wrote: