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DIY Ferric Oxalate Synthesis for Kallitype

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Raghu Kuvempunagar

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Like several of my printmaking friends in India, I was looking for a simple procedure for synthesising Ferric Oxalate for use in the Kallitype process as importing Ferric Oxalate was both complicated and expensive. So I explored several methods to make Ferric Oxalate at home for use in the Kallitype process. Pretty soon I realised that some of the well-known methods for synthesising dry Ferric Oxalate are cumbersome and not well-suited for the low volume users like me. Also, dissolving dry Ferric Oxalate is a pain taking a lot of time and effort.

After some trials, I arrived at the following simple process that allows me to make 20% Ferric Oxalate solution from scratch in about 15 minutes:

Distilled water: 30 ml
Oxalic Acid (Dihydrate): 12 g
Sodium Carbonate: 9.9 g
Ferric Nitrate (Nonahydrate): 25 g
Distilled water to make: 75 ml

Mix Oxalic Acid in distilled water and stir well. Not all of it will go into solution, but that's Ok. Next add Sodium Carbonate in small amounts to the mixture and stir well. Carbon Dioxide will be released with every addition of Carbonate and the solution will fizz. After all Carbonate has been added and the mixture has been stirred well, you get a milky white solution. Now add Ferric Nitrate and stir well. A green coloured solution forms. Top it to 75 ml by adding requisite volume of distilled water. Store the solution in a dark glass bottle tightly stoppered. When kept away from light and in reasonably cool temperature, it stays good for over three months.

The solution thus synthesised is meant be used in the Kallitype process in place of 20% Ferric Oxalate solution. I follow the Kallitype process delineated by Sandy King in his Unblinkingeye article. At 1 ml / A4 sheet, this procedure gives you enough Ferric Oxalate solution to make ~75 A4 sized prints. Of course, one make only as much sensitiser as needed for a working session as it takes not much time to make the desired volume of sensitiser from scratch.

Purists will rightly point out that the solution contains Sodum Nitrate along with Ferric Oxalate. But that doesn't do any harm to the printing. I and my friends have used Kallitype sensitiser made using the above method successfully and are quite happy with it. If you try this method, let me know how it worked for you.
 
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Raghu Kuvempunagar

Raghu Kuvempunagar

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Oh, this is great! I might try this some time;

Fantastic! If and when you try it, I would truly appreciate if you could tell me if you notice any significant difference in the results compared to a sensitiser made from powdered Ferric Oxalate.
 

koraks

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Well, that's a bit of a challenge; last time I tried to order it, I waited for weeks and then received an envelope with the exact amount of money I paid for it in coinage, with a note informing me the supplier couldn't deliver...so that's why your solution (pun intended!) comes in so handy.
 
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Raghu Kuvempunagar

Raghu Kuvempunagar

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Well, that's a bit of a challenge; last time I tried to order it, I waited for weeks and then received an envelope with the exact amount of money I paid for it in coinage, with a note informing me the supplier couldn't deliver...so that's why your solution (pun intended!) comes in so handy.

My bad, I assumed that you already have powdered FO, I don't know why. :smile:
 
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koraks

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Well, my collection of (photo)chemistry that I like to refer to as "the drinks cabinet" is certainly reasonably well-stocked, but FO is one of those things that never really materialized in it. EU sources have always been scarce or (in my view) overpriced. And I have to admit that I have always struggled to find a really solid reason to do kallitypes if Van Dyke Brown produces a print that as far as I can tell is nearly identical but without the somewhat problematic ferric oxalate. This, btw, is one of the reasons I find your invention so interesting, because it would allow me to systematically compare the two and perhaps figure out why kallitypes are so popular while Van Dyke appears (to me at least) to always be treated with a little less enthusiasm.
 

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Years ago I was wondering if you could take commercial Yellow iron oxide, add oxalic acid and make FO. In one bottle, I used excess iron oxide (based on theoretical stoichiometry,) in another I used excess oxalic acid. I left them for a while. Nothing happened for days, weeks, months. I stopped checking after a while. Some 2 years passed and I happen to check on the bottles as I was cleaning out stuff for my move. Well, there was a nice green solution in both of the bottles. One with the excess iron oxide still had some pigment. The other one is nice and clear. Somewhere between 6 months and 2 years, there was complete reaction. Never did any printing or checked if this is indeed photosensitive. I still have the bottles. Not a very practical method but interesting!
 

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revdoc

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I did a similar exercise a few years back with ferric oxide granules (used to purify fish tank water) and citric acid. The result was similar - I got ferric citrate, but it took a few months.

I think it might still be viable in some situations. I guess if you start the process when you already have enough for a few months, it will be ready when you need it. You'd have to deal with any excess oxalic acid if you're making kallitypes.
 
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Raghu Kuvempunagar

Raghu Kuvempunagar

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Years ago I was wondering if you could take commercial Yellow iron oxide, add oxalic acid and make FO. In one bottle, I used excess iron oxide (based on theoretical stoichiometry,) in another I used excess oxalic acid. I left them for a while. Nothing happened for days, weeks, months. I stopped checking after a while. Some 2 years passed and I happen to check on the bottles as I was cleaning out stuff for my move. Well, there was a nice green solution in both of the bottles. One with the excess iron oxide still had some pigment. The other one is nice and clear. Somewhere between 6 months and 2 years, there was complete reaction. Never did any printing or checked if this is indeed photosensitive. I still have the bottles. Not a very practical method but interesting!

Interestingly the solution is darker and greener than what I expect from a 20% solution of Ferric Oxalate. What is the concentration of FO in the resulting solution?

Wouldn't the synthesis be much faster if Yellow Iron Oxide is first reacted with Nitric Acid to get Ferric Nitrate and then react it with Oxalic Acid?
 
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