Uh oh... I’m in trouble.

Máx Arnold said:

I quote from http://www.alternativephotography.com/update-ferric-gum-process/
"Peter (...) added ferric ammonium oxalate to the sensitiser to make it faster."

Now, this is not the way I would do it.
I haven't seen it posted anywhere, so I'll describe it to you:

When I bought the Ferric chloride it came on a stock solution of around 48%. I found that diluting it caused the gum to not harden properly. Note that you have to use gum arabic (you probably have some). So, normally I would take around 15ml or around 1 tablespoon of the ferric chloride stock solution, and saturate it with oxalic acid crystals. The ferric chloride forms a complex with the acid, which is much more sensitive to light, without changing the concentration. I'm not giving exact measures here... the trick is to saturate it with oxalic acid.
Please note that exposure to oxalic acid in (very) high concentrations can be toxic. Beets and spinach contain it and a diet high on them can lead to kidney stones. I use gloves for handling this stuff, even if it's no bichromate. (I don't want to alarm... it's just normal disclaimer. But this is much better than bichromate)
The normal exposure time that I have on full sun is 15 minutes. You may have to see and try yours.

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Hi, Max:

Are you brushing on the chloride/oxalate first on the paper, expose and then treating with gum - is that the basic process?

:Niranjan.

Niranjan: Yes, that's it.
I've found that it's better to wash under a tap with running cold water, but have it running gently, as the gum will not adhere to the paper easily.

Máx Arnold said:

Niranjan: Yes, that's it.
I've found that it's better to wash under a tap with running cold water, but have it running gently, as the gum will not adhere to the paper easily.

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That's a very interesting process...almost like gumoil in mechanics of how paint is applied all over and the excess washed off - the difference being the sensitizer is separated from the gum whereas the pigment is mixed in with the gum. One of these days, I'd like to give it a shot. I have all the ingredients on hand.

Regarding the ferric gum process...

I am one of those who helped out with the experiments described in the article cited above (i.e. http://www.alternativephotography.com/update-ferric-gum-process/).

There was significant discussion on the alternativephotography.com forum as we worked through some of the details. Alas, those discussions were lost in a software update at some point in the past. However, if anyone is interested in these details, I have put pdf files containing most of that discussion (I had printed copies in my records) on my website, here: http://gorga.org/blog/?p=339

It is hard to believe that that work is ten years old. I have not done much with the process since then, but I keep meaning to get back to it. I have not kept in touch with the other collaborators, but I do not think that anyone involved back then has really followed up on the process or is using it currently.

The ferric gum process, including the glyoxal "fixing" of the image certainly works, but I think that there is still room for improvement/refinement.

I got involved in this back ten years ago because I had dabbled in gum printing but had decided that I could not justify the environmental costs of using chromium salts to myself, and had stopped making gum prints for that reason.

I am very glad to see that Max has tried the technique and that others are interested.

I am currently in the middle of learning how to apply metal leaf to prints on vellum (both inkjet and cyanotypes) a la' Dan Burkeholder. Maybe I'll try some more ferric gum printing after I get that worked out. Folks here will be the first to know! ;-)

Thanks, Frank. I've downloaded the three PDF files and will look them over soon.

I'm very interested in this. I've liked the idea of making separation based prints for a long time, but carbon appears difficult to master, and gum bichromate raises the same objections for me as for you, as well as UV blocking by the pigment limiting the opacity reachable in each layer (and more layers increases problems with registration), and the resolution limitations inherent in hardening from the top (the reason carbons are generally done as transfers). If ferric gum can be perfected to the point of layering in color, it'll be exactly what I've wanted to do.

I was one of the collaborators with fgorga in the ferric gum experiments about 10 years ago. I produced a number of monochrome prints and a total of two tricolour prints. The benefit of the process is the hardening that goes from the bottom up, and its safer chemistry. There is a much longer exposure time, maybe 15-20 minutes in the sun. The greatest challenge was removal of the iron. The process seems to produce an insoluble complex of iron and gum but if the iron is removed by acidification as you would typically want to do as iron is catalytic to oxidation of organic materials like cellulose, the gum becomes soluble again. In order to do a tricolour print, I post hardened the print in a dilute glyoxal soln, hung it to dry and then went on to the next layer. Finally, once all of the layers were hardened, I placed the print in an acidified bath to wash out the iron. Too long in the glyoxal tray seemed to cause the gum to soften, so it was only for a few minutes. It may have been that the glyoxal being acidic, was attacking the complex. After walking away from these experiments, I later learned that glyoxal actually acts more effectively if made slightly alkaline, with for instance, sodium bicarbonate (At least for gelatine hardening, never tested this with gum) but I never tried this and have not experimented with the process in these 10 years.

I still have all of the test prints in a folder and remain interested for the possibilities, but I can’ seem to find the extra time to get back to trying to move this along and I am active with other alt processes. Maybe other experimenters can find novel solutions.



peter

I forgot to mention that the original article “My Way with Gum”by Michael Andrews, from 1983, is available here

https://archive.rps.org/archive/volume-123/747364

scroll to sheet 70 (pg 64, 65)

PGum said:

I forgot to mention that the original article “My Way with Gum”by Michael Andrews, from 1983, is available here

https://archive.rps.org/archive/volume-123/747364

scroll to sheet 70 (pg 64, 65)

Click to expand...

Thanks, Peter for some more color on this process and the link to the original work. Sometimes it is better to walk away from the process for a while and come back later with a fresh perspective. May be fresh set of eyes/hands (not mine) will move forward this intriguing process.

A question: When you say difficulty in removing the iron, you are not talking about the iron trapped in the paper underneath the surface which did not make contact with the gum and the highlights where the iron(iii) mostly got converted to iron(ii) and the gum got mostly developed out. In other words, if you blanketed the whole paper with UV to convert all ferric to ferrous, that would have resulted in a paper white print, right? It is then mostly the iron(iii) inside the matrix of gum that is difficult to wash out. And if it is removed then it is counter to the solidification of gum making it more soluble, thus losing density. Am I understanding this correctly?

A couple of thoughts (wild conjectures):

Can you use a part of the so-called Ferric Carbon process (or the Chiba process) to crosslink the matrix using hydrogen peroxide, at least in case pf gelatin. For that one would have to convert the Fe(iii) to Fe(ii) by doing a blanket UV exposure post-development, then treat with hydrogen peroxide generating free radicals in reaction with Fe(ii) which then would crosslink the gelatin. Once the gelatin is hardened then the iron can be removed with EDTA as it is done in the Ferric Carbon process. I am not sure hydrogen peroxide would do the same thing with gum or not.

Secondly, why not just leave the iron in the print but actually converting it to oxide/hydroxide by treating with an alkali instead of an acid, like how a cyanotype is bleached before toning. The color will change warmer because of that. And the ferric hydroxide aka rust should not harm anyone. May be....

:Niranjan.

Hi Niranjan,

The difficulty lies in removing all iron. Perhaps one could find an agent that would only remove the paper bound iron and not that which is complexed with the gum, but I was unsuccessful with this approach. EDTA had a similar negative effect on the image as acidifiers did.

After you develop the image in water, the anions ( chloride, and perhaps oxalate if you used this as well), are lost, so I would expect that the iron would no longer reduce under UV however I didn’t test this and it is possible.

If you were able to reduce it and develop in peroxide, then there would be hope for crosslinking if the colloid was gelatine, but this does not work effectively for gum.

You can sub in gelatine in this process, but for me it made for a very high contrast image, something akin to a vintage photocopy. Once again, I did not do enough with gelatine to say it can’t be made to work more effectively.

You could certainly leave it as is, after development. You wouldn’t need to treat it with an alkali as the free iron will convert to its hydroxide just through water development. It will have an orange cast but will likely not be archival if that matters.

peter

PGum said:

Hi Niranjan,

The difficulty lies in removing all iron. Perhaps one could find an agent that would only remove the paper bound iron and not that which is complexed with the gum, but I was unsuccessful with this approach. EDTA had a similar negative effect on the image as acidifiers did.

After you develop the image in water, the anions ( chloride, and perhaps oxalate if you used this as well), are lost, so I would expect that the iron would no longer reduce under UV however I didn’t test this and it is possible.

If you were able to reduce it and develop in peroxide, then there would be hope for crosslinking if the colloid was gelatine, but this does not work effectively for gum.

You can sub in gelatine in this process, but for me it made for a very high contrast image, something akin to a vintage photocopy. Once again, I did not do enough with gelatine to say it can’t be made to work more effectively.

You could certainly leave it as is, after development. You wouldn’t need to treat it with an alkali as the free iron will convert to its hydroxide just through water development. It will have an orange cast but will likely not be archival if that matters.

peter

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So you must be the Peter in this link:

http://www.alternativephotography.com/update-ferric-gum-process/

Looks like a very good synopsis of what you guys did back then. Nice color prints as well. I am intrigued enough to want to try at some point - I have everything except the pigment which I have on order. I think we should open a separate thread if we want to discuss any further since it is way OT from OP's initial subject of discussion.

:Niranjan.

Peter,

Thanks for the update / information. I, too, have had thoughts about looking at the ferric gum process again but, alas, other things always seem to have higher priority. Hopefully, this renewed interest will spark some progress.

Niranjan,

Yes, that would be the same Peter!

I, for one, am looking forward to seeing how you progress and I think that a new thread is a very good idea.

If memory serves, the basic problem is that the iron seems to be important for the stability of the image formed by the light. If one removes too much of the iron, the image falls apart. If one look leaves too much of the iron, one gets staining. Therefore, one needs to find a way to stabilize the gum image before removing the iron. Thus, the glyoxal treatments.

I was interested to see Peter's comment regarding replacing the gum with gelatin. I have in my old notes, the idea to try other gums besides gum arabic, but did not pursue this.

Just so folks know, gelatin is fundamentally different chemically than gum arabic, and other gums. Gelatin is protein-based, a polymer of amino acids. Gums are carbohydrate (sugar) polymers.

This was one process I wanted to try and then never got to. It'd seemed to have disappeared after an initial set of articles on the alt photo forum. Really looking forward to hearing what comes of this! The idea of carbon transfer like results without all the hassle is very appealing. Hope the iron problem is solved.