Ferric lactate type sensitizers


Pfriedrichsen
 

(I copied over the last few messages from the ferric oxalate thread.)

Hi Mike, 

I didn’t attempt to calculate the stoichiometry on my FAL solution. It might be suspect starting from a ferric chloride solution ( source of ferric hydrate)of which I don’t know the exact strength as it is commercial grade copper etchant. I have used this same etchant for making FAC and the colour is traditional so I don’t think it is impurities either that are affecting the colour.

The print does have an “ammonia blue” but it does not fade away when left indoors. Attached is an image of the FAL on the left, and FAC cyanotype on the right ( overexposed mind you) the FAL strip is about 4 months old. 


Peter Friedrichsen

 






On Tue, Nov 17, 2020 at 04:21 AM, Pfriedrichsen wrote:

In regards to lactate, some time ago I made some ferric ammonium lactate (FAL) using precipitated ferric hydrate ...  Here is the unusual outcome: The prints are deep but have a muted violet hue ...  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 a more traditional cyanotype hue.

That's very interesting, Peter. 
I'm wondering if there is a way to change the title of a thread on this new server - say, to "Ferric lactate sensitizers" Advice anyone?
I seem to have led us away from Niranjan's original ferric oxalate question...

Do you know the stoichiometry of your FAL complex?
Regarding your violet coloured cyanotype and its reversion, one sees the same behaviour with ammonia vapour: here is a quote from my Cyanomicon §8.1, p.261:

Exposure just to ammonia vapour, rather than solution, does not fully

hydrolyse the Prussian blue but imparts to it an impermanent, though

striking, violet colour; this toning is reversible within a few hours simply

by restoring the print to air, when the occluded ammonia gas is

presumably lost, and the pigment reverts to its original blue colour.

It is conjectured that this effect may be due to ammonia causing a

reversible deprotonation of water coordinated to Fe(III) in the PB lattice;

transformation of the ligands from OHto OHwould affect the

energy of the electron charge-transfer transition between Fe(III) and

Fe(II), and change the colour.

Perhaps your resulting print contains some free NH3?

-- 
Mike Ware
https://www.mikeware.co.uk

_._,_._,_

 

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!
 
Peter Friedrichsen
 

On Nov 17, 2020, at 5:51 AM, mike@... wrote:

OK, Niranjan. 
Lactotype it is, if you prefer the Latin root, or more correctly Galatype, if the Greek ( Γαλα = 'milk'). I like the hybrid Galactotype because it has a cosmic ring to it!

Why start with Fe(II) salts, when Fe(III) salts are cheaply available? Using H2O2 as an oxidant, with simple aliphatics around, might invite the attention of those who question your motives...
verbum sapienti.

17 years ago, I tried ferric lactate mixed with silver lactate as a sensitizer, and got quite fair brown argentotype images, but some loss in the processing. Silver lactate by itself also prints out, as discovered, I think, by Liam Lawless, but tends to fog in the processing. Ferric lactate would probably also provide a cyanotype process.
-- 
Mike Ware
https://www.mikeware.co.uk

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