Direct tannin process (no bleaching, no Potassium ferricyanide, just ferric oxalate/water and hydrogen peroxide + tannins)

[Raghu Kuvempunagar]

They may be but to what end is not clear to me.

:Niranjan.

In the case of Catechol toner, adding Peroxide to it makes it produce more dye/stain.

 

[nmp]

Oh yes, I think so. I was imagining mixing and using immediately. The question would be whether the oxalate reaction would happen or whether all the peroxide would be used up in other reactions. I've been playing with botanical cyanotype toners and with some of them you can visually see the liquid change color when exposed just to air. Annette Golaz says that higher pH promotes oxidation in the toners, so plays more of a role than just converting prussian blue.

Yeah, in alkaline medium, tannic acid gets de-protonated (-OH to O- and H+) making it more prone to oxidation, changing color. It also tones faster and as I have noticed, tends to stain the paper more as well. So it's better to keep it neutral to slightly acidic.

:Niranjan

 

[Raghu Kuvempunagar]

My first attempt didn't go well but the mistake is mine only. I underestimated the exposure thinking it would be very short like Cyanotype Rex. I'll try again sometime later with generously more exposure.

 

[nmp]

My first attempt didn't go well but the mistake is mine only. I underestimated the exposure thinking it would be very short like Cyanotype Rex. I'll try again sometime later with generously more exposure.

Why not do an old fashioned step wedge to figure out the exposure.

:Niranjan.

 

[Raghu Kuvempunagar]

The idea of using coffee dicoction yesteday was not a good one - it produced a very pale image. Today I gave another try with Haritaki and it worked a lot better. Haritaki produces good black tones in the print and the toner also turns black within a couple of minutes. Apparently Haritaki contains Tannic and Gallic acids.

BTW I noticed that Peroxide bath turned yellow-brown very soon - probably indicative of Ferric Oxalate getting into solution.

 

[NedL]

... BTW I noticed that Peroxide bath turned yellow-brown very soon - probably indicative of Ferric Oxalate getting into solution.

That makes sense!

 

[Igor Jansen]

The idea of using coffee dicoction yesteday was not a good one - it produced a very pale image. Today I gave another try with Haritaki and it worked a lot better. Haritaki produces good black tones in the print and the toner also turns black within a couple of minutes. Apparently Haritaki contains Tannic and Gallic acids.

BTW I noticed that Peroxide bath turned yellow-brown very soon - probably indicative of Ferric Oxalate getting into solution.

Nice! Before going to peroxide there is the first water wash (say 2-10 minutes), which should remove most/all ferric oxalate. The peroxide oxidation can be quite rapid, when using concentrated peroxide (in 3% peroxide its matter of secods, I keep it there for say a minute just in case…)… In other words I did not see any (significant??) yellowing of the peroxide…

 

[Raghu Kuvempunagar]

Nice! Before going to peroxide there is the first water wash (say 2-10 minutes), which should remove most/all ferric oxalate. The peroxide oxidation can be quite rapid, when using concentrated peroxide (in 3% peroxide its matter of secods, I keep it there for say a minute just in case…)… In other words I did not see any (significant??) yellowing of the peroxide…

Yes, I followed your prescribed routine including first water wash. Ferric Oxalate that goes in the Peroxide bath is the one that forms after the oxidation of Ferrous Oxalate and not the residual sensitiser. Peroxide bath was for a couple of minutes and was approximately 2%. That Haritaki toner turned black from original brown colour also indicates some Ferric Oxalate going into solution during the toning bath and reacting with Tannins in the toner. If you get a chance, please try toning with Tannic Acid itself and you might also notice the same thing happening to your toner solution.

 

[FotoD]

Maybe fume the print with ammonia in humid air, instead of using H2O2? Could help the highlights, if the reaction isn't too slow to be practical.

 

[ced]

Interesting but wonder of smoothness of tone transitions anyone care to post pleasing results?

 

[Jan de Jong]

Perhaps if you skip the oxidation step and go straight to tannin bath, you would flip the image - i.e. insoluble ferric tannate where there is no exposure and soluble ferrous tannate where there is exposure which can be washed out. This would be a positive process. You will still be some contrast loss but it would be less than that introduced during the re-oxidation step. I think Jim Patterson over at altphotolist had something like this.

Almost off topic, but same base, but to answer your assumption Niranjan.
2gr FAC
1gr tartaric acid
10ml of den Water
Expose onion slices direct on paper Paper is Inkjet Epson Glossy
Expose with UV-flashlight some 30 seconds selectively.
Developed direct in Haritaki - yes gives direct positive. not very much contrast but it is good visible as below image.

 

[nmp]

Almost off topic, but same base, but to answer your assumption Niranjan.
2gr FAC
1gr tartaric acid
10ml of den Water
Expose onion slices direct on paper Paper is Inkjet Epson Glossy
Expose with UV-flashlight some 30 seconds selectively.
Developed direct in Haritaki - yes gives direct positive. not very much contrast but it is good visible as below image.
View attachment 416082

Good demo of the concept. Yeah, it would be kind of hard to get contrast as both ferric and ferrous ammonium citrate molecules are soluble in water. Perhaps brush coating or better yet with rod coating it might get better.

Thanks for sharing.

:Niranjan.

 

[Jan de Jong]

Good demo of the concept. Yeah, it would be kind of hard to get contrast as both ferric and ferrous ammonium citrate molecules are soluble in water. Perhaps brush coating or better yet with rod coating it might get better.

Thanks for sharing.

:Niranjan.

Indeed Brush or Rod coating should be used else the Haritaki goes to waste very quick as it will adhere to the dissolved iron hence the Haritaki solution is getting very black quick.

 

[nmp]

Indeed Brush or Rod coating should be used else the Haritaki goes to waste very quick as it will adhere to the dissolved iron hence the Haritaki solution is getting very black quick.

Another way to reduce bleeding is develop the print upside down without agitation.

Here is the link to Jim Patterson's Iron Black Positive process that I alluded to earlier (he uses some other molecules that bind to Fe(3) and make a black pigment.) He also found FO the best among FO/FAO/FAC.

https://groups.io/g/altphotolist/topic/90976156#msg7019

:Niranjan.

 

[Donald Qualls]

how paper is corroded/eaten away by iron gall ink.

Fortunately, this is an effect of the sulfuric acid that remains in ink made from iron sulfate; it shouldn't be an issue with an iron oxalate sensitizer.

 

[PGum]

I wonder if after exposure, and wash, you hang the print to dry and leave it for a few days. Would the ferrous oxalate oxidize by air to ferric oxalate? Any one know what oxidation state is favourable to iron ii oxalate in air? Other than the long wait, it might provide a deeper print without the loss of ferric oxalate during the wet oxidation step.

 

[fgorga]

I wonder if after exposure, and wash, you hang the print to dry and leave it for a few days. Would the ferrous oxalate oxidize by air to ferric oxalate? Any one know what oxidation state is favourable to iron ii oxalate in air? Other than the long wait, it might provide a deeper print without the loss of ferric oxalate during the wet oxidation step.

Iron(II) is not stable in air; it will oxidize to iron(III). The products are a mix of iron(III) oxides and hydroxides (i.e. rust). Thus, this reaction requires the presence of water in order to occur at any appreciable rate.

If one could keep the print in a high humidity environment your idea might work. I am not sure how long you would have to wait though.

 

[Raghu Kuvempunagar]

Earlier this week, I got this idea of avoiding solubility issues of Ferric Oxalate by converting the Ferrous Oxalate image to Ferric Hydroxide and toning:

#1 Sensitise the paper with Ferric Oxalate, dry and expose under a negative to UV light.

#2 Rinse the exposed print in neutral pH water thoroughly to remove residual sensitiser. The image on the print is made up of Ferrous Oxalate.

#3 Rinse the print in dilute (1%) Sodium Hydroxide solution. Ferrous Oxalate gets converted to Ferrous Hydroxide (insoluble). Rinse in water to remove residual Sodium Hydroxide and Oxalate. The image on the print is made up of Ferrous Hydroxide.

#4 Rinse the print in dilute (1%) Hydrogen Peroxide solution. Ferrous Hydroxide gets converted to Ferric Hydroxide (insoluble). Rinse in water to remove residual Peroxide. The image on the print is made up of Ferric Hydroxide.

#5. Tone the print.

It went well upto step #4. Toning with Haritaki did produce a toned image but with significant highlight fog. Will give another try with coffee or tea someother time.

 

[nmp]

Iron(II) is not stable in air; it will oxidize to iron(III). The products are a mix of iron(III) oxides and hydroxides (i.e. rust). Thus, this reaction requires the presence of water in order to occur at any appreciable rate.

If one could keep the print in a high humidity environment your idea might work. I am not sure how long you would have to wait though.

In alkaline conditions, conversion to Fe(3) is much faster. I would try and simply treat the print (after washing out the Fe(3)) in NaOH or ammonia and drain but not dry and wait for the green Fe(OH)2 to convert to red Fe(OH)2 and you are good to go for tannic acid bath.

:Niranjan.

Edit: Looks like Raghu beat me to it...

 

[nmp]

Earlier this week, I got this idea of avoiding solubility issues of Ferric Oxalate by converting the Ferrous Oxalate image to Ferric Hydroxide and toning:

#1 Sensitise the paper with Ferric Oxalate, dry and expose under a negative to UV light.

#2 Rinse the exposed print in neutral pH water thoroughly to remove residual sensitiser. The image on the print is made up of Ferrous Oxalate.

#3 Rinse the print in dilute (1%) Sodium Hydroxide solution. Ferrous Oxalate gets converted to Ferrous Hydroxide (insoluble). Rinse in water to remove residual Sodium Hydroxide and Oxalate. The image on the print is made up of Ferrous Hydroxide.

#4 Rinse the print in dilute (1%) Hydrogen Peroxide solution. Ferrous Hydroxide gets converted to Ferric Hydroxide (insoluble). Rinse in water to remove residual Peroxide. The image on the print is made up of Ferric Hydroxide.

#5. Tone the print.

It went well upto step #4. Toning with Haritaki did produce a toned image but with significant highlight fog. Will give another try with coffee or tea someother time.

I guess one problem that might be envisioned with this approach is that the print has to be thoroughly washed out of the unexposed Fe(3) before alkali treatment as, if present, it will also form insoluble Fe(OH)3 which will be a source of fog. Wonder if it requires a "clearing" step a la Pt-Pd process to augment removal of ferric iron at step #2. Don't know if that would result in a loss of ferrous oxalate as well or not.

:Niranjan.

 

[Raghu Kuvempunagar]

Earlier this week, I got this idea of avoiding solubility issues of Ferric Oxalate by converting the Ferrous Oxalate image to Ferric Hydroxide and toning:

#1 Sensitise the paper with Ferric Oxalate, dry and expose under a negative to UV light.

#2 Rinse the exposed print in neutral pH water thoroughly to remove residual sensitiser. The image on the print is made up of Ferrous Oxalate.

#3 Rinse the print in dilute (1%) Sodium Hydroxide solution. Ferrous Oxalate gets converted to Ferrous Hydroxide (insoluble). Rinse in water to remove residual Sodium Hydroxide and Oxalate. The image on the print is made up of Ferrous Hydroxide.

#4 Rinse the print in dilute (1%) Hydrogen Peroxide solution. Ferrous Hydroxide gets converted to Ferric Hydroxide (insoluble). Rinse in water to remove residual Peroxide. The image on the print is made up of Ferric Hydroxide.

#5. Tone the print.

It went well upto step #4. Toning with Haritaki did produce a toned image but with significant highlight fog. Will give another try with coffee or tea someother time.

I gave this process another shot today. Here's how the print looks after step #4.

I used multiple wash steps throughout. Highlights are reasonably clear.

 

[FotoD]

Looks promising!

Are you going to tone it with tannins?
Do the uncoated parts of the paper stay clear?