Kallitype with Fe(III) Ammonium Oxalate?
I've been doing Kallitypes for a while using the normal ferric oxalate/silver nitrate sensitizer. After reading Mike Ware's discussion of ferric oxalate -vs- ferric ammonium oxalate (and running low on the former) I tried using the ammonium as a direct replacement (20% w/v with 1% w/v oxalic acid acid + 10% w/v silver nitrate mixed 1:1).
I got pretty good results, very nice tonality but a little weak. I did this off the cuff and expect I may need more of the ammonium to get an equal amount of ferric ions in my sensitizer, but before I reinvent the wheel, has anyone done this?
My primary interest in the ammonium is that it's cheaper, easier to find, and much more soluble.
Not tried but my back of the envelope calculation runs like so:
Ferric oxalate = C6Fe2O12.5(H2O) mw 465 ish. 20% solution ~0.43M solution and so ~0.83M Fe
Iron(III) NH3 ox C6H12FeN3O12.3H2O mw 428ish 1M 20% solution ~0.46M solution and so ~0.46M Fe
so if its *just* the iron Id double my concentration. What the NH3 and oxalate do in the reaction I have NFI. Perhaps ask Mike Ware via his website?
Thanks for saving me the math
I'm a bit hazy on the exact reaction my self. Certainly the Iron is the most important as that's what's photosensitive. Comparing formulas that use the NH4 it does seem to be mixed at about double concentration.
I've been speculating on what the other ions may do but when you get down to it I have NFI either. I think I will drop Dr Ware and email as you suggest if I get an answer I'll follow up here.
So here is Mike Ware's response to my query in case anyone is curious (I promise I'll now stop talking to my self)...
As you may have guessed, this is not the first time this question has
been asked, but it's a good one and deserves a sensible answer.
Since you have a copy of my 'Chrysotype Manual' (Bravo! Would that
more did!) then you can read my reasons for preferring ammonium iron
(III) oxalate over iron(III) oxalate in detail on pp138-139, and
these reasons apply in general, across all the iron-based processes.
There are also some remarks to this effect buried in my webpages, see:
There is an attempt to explain the differing photochemistry of the
two substances here:
and the role played by the ammonium ion in particular is suggested here:
having cited all this, I'll address your specific question about
replacing iron(III) oxalate by ammonium iron(III) oxalate in Kallitype:
First, concentrations. You're right: about twice the weight of the
latter in the same volume will give nearly the same iron(III)
concentration as the former. Actually slightly more: the factor is
about 2x 428/466 = 1.84, but I wouldn't be fussy. Ammonium iron(III)
oxalate is very soluble and easily dissolved as you will know.
The problem with the Kallitype process - and the reason why ammonium
iron(III) oxalate is not universally recommended for it - is the
precipitation of the very insoluble silver oxalate, which is greater
with ammonium iron(III) oxalate, because it generates more free
oxalate ion. Some folk don't mind spreading a thick suspension of a
solid onto their paper as a sensitized coating, but I do, and I
cannot believe it is conducive to good print quality. My philosophy
of siderotype is that the sensitizer should be a true aqueous
solution, to penetrate the cellulose fibres, and it should not hold
any solid matter in suspension, which will just lie on the paper
surface, and probably wash off.
Using iron(III) oxalate in Kallitype, it is possible to suppress the
precipitation of silver oxalate altogether - at least for a time - by
adding excess iron(III) salt such as the nitrate - see the
experiments described in Dick Steven's book. With ammonium iron(III)
oxalate you will always get a precipitate. I have tried quite a
number of ways to prevent this - without success. The first person to
do it will earn my respect and undying thanks! I am a great fan of
ammonium iron(III) oxalate, and use it wherever I can (e.g. my New
Cyanotype etc) but for iron-silver process I have had to compromise,
and use the less satisfactory ammonium iron(III) citrate in my
Argyrotype process. If I could have used ammonium iron(III) oxalate
without precipitating silver oxalate, I would have.
I think that about summarises my thoughts. You are welcome to quote
and publish this response on the APUG forum, if you think it will
help others. I don't think I'm subscribed to do this myself.
All good wishes, and let me know how you get on,
Thanks. He is a fount of wisdom!
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You may like to read the thread I started whilst I was experimenting with kallitypes using FAO. There's some input from Sandy King there too - he's very experienced with kallitypes. Wishing you better results with it.
Regarding the use of AFO for kallitype I agree with the comments by Mike Ware. It may be possible to make prints of excellent technical quality with silver nitrate and AFO but I have never been able to do so in spite of quite a bit of experimentation.
Originally Posted by kevs
Clearly more investigation is needed
My initial tests we admittedly flawed in that I had insufficient Fe(III) in the sensitizer, and I'd blamed this for my low DMax. Sandy saw this as well, but didn't give a formulation for the tested sensitizer (presumably this was in the U of S link that is now dead).
On Arches 140lb HP I did get fine detail and clean highlights in both 20% NaCitrate developer and a Borax/Rochelle developer (more or less from the Stevens book). Both of these were souped with K2Cr2O7 (about %0.02 final concentration).
I did have a milky suspension rather than a clear solution for the sensitizer, the higher oxalate concentration in a solution with sufficient Fe(III) will probably make this worse.
Guess it's time to pull out the step wedge and do some more controlled testing...
Interesting thread this and very useful for my experiments.
I separated out the sensitizer and just coated with the ammonium iron(III) oxalate. Very quick exposure times, then developed in a solution of Silver nitrate and tartaric acid. I imagine this can be reused for quite a while but will still be more expensive than adding it to the coating.
Bonus is it works - very nice dark tones. I developed after in a solution of Rochelle salt and Borax although I suspect this isn't necessary.
Here's an example --- http://www.flickr.com/photos/sebsuss...ream/lightbox/ - more testing needed especially in terms of the right neg. Step wedge testes definitely needed
Thank you for this information.
I am getting my Cyanotype process under control using both traditional and Ware formulated senitizers.
Kallitype was going to be my next step on my alt process wandering path.
my real name, imagine that.