Raghu Kuvempunagar
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They may be but to what end is not clear to me.
:Niranjan.
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.
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.
... BTW I noticed that Peroxide bath turned yellow-brown very soon - probably indicative of Ferric Oxalate getting into solution.
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…
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.
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.
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.
how paper is corroded/eaten away by iron gall ink.
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.
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.
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.
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