Gold/Thiourea Toner and Archival Process for Van Dyke Prints

[Dan Pavel]

Sorry for resurrecting the thread but it happened that I made some VDB gold/thiourea toning tests these days and I think the results are interesting. I was interested in toning to completion and tested toning before and after fixing. The paper used was Arches Platinum. The results are, somehow, surprising. Even after approx. 40min. of toning I couldn't get neutral tones (one of my goals) when toning before fixing. Toning after fixing produced better results in this regard and the blacks were even darker than in Pt/Pd. These are some of the tests:

My method of toning to completion after fixing involves:
1. Process the print traditionally, including the final wash.
2. Let it completely dry.
3. Tone it for approx. 40 min.
4. Take off the toner and rinse briefly.
5. Pour water in the tray (without any toner) just sufficient to cover the print and let it rest for approx. 40 min. I use some glass weights to keep the paper at the bottom of the tray. It will get more neutral tonalities during this stage.
6. Wash it for approx. 3 min. and let it dry.

During and after drying it will continue to get more neutral tonalities and darker blacks for 1-2 days, probably as the rests of toner from the fibers of the paper still work. After approx. 2 days it gets it's final tonalities and won't change anymore.

I consider adding a final stage of clearing (the traditional Pt/Pd clearing baths and final wash) after it gets its' final tonality, but probably it's not really necessary.

 

[koraks]

During and after drying it will continue to get more neutral tonalities and darker blacks for 1-2 days, probably as the rests of toner from the fibers of the paper still work

I suspect this has more to do with the humidity of the paper reaching equilibrium. What happens if you take a freshly processed print, blot it dry, then blast dry with a hairdryer, and ultimately run a hot clothes iron over it? Compare that print to one you allowed to dry naturally over the course of a few days. I expect you'll find the 'turbo-dried' print to be even slightly more neutral in tone.

Thanks for posting this comparison; it's very interesting indeed. I must say I've not done the same before/after fixing test with VdB; I did with salted paper prints, but the process is sufficiently different for other phenomena to come into play in that scenario.

Interestingly, there are some hue variations in both prints as you cross the tonal scale from dark to light. It might be interesting to plot these; I sometimes make Lab plots where I plot a* against b* for different densities. You can see "the print walk through the hues" as it were, that way. It's sometimes educational and can help also in developing hypotheses of what's going on.

 

[nmp]

I wonder if this has something to do with the fact that toning after fixing leaves AgCl in the paper which over time would reduce to give back metallic Ag, basically doubling the metallic population - each Ag in the original image gives one Au and one Ag. In theory, you can probably take that image and tone it again and replace the Ag once again with one Au and one Ag, and so on building more and and more density. That would be an interesting experiment.

Conversely, if the print is fixed again post toning, then may be it won't develop darker/more neutral tonality and match more closely the print that was toned before fixing.

:Niranjan.

P.S. What is the Pt/Pd Chiba process, by the way?

 

[FotoD]

Sorry for resurrecting the thread but it happened that I made some VDB gold/thiourea toning tests these days and I think the results are interesting. I was interested in toning to completion and tested toning before and after fixing. The paper used was Arches Platinum. The results are, somehow, surprising. Even after approx. 40min. of toning I couldn't get neutral tones (one of my goals) when toning before fixing. Toning after fixing produced better results in this regard and the blacks were even darker than in Pt/Pd. These are some of the tests:
View attachment 389895
My method of toning to completion after fixing involves:
1. Process the print traditionally, including the final wash.
2. Let it completely dry.
3. Tone it for approx. 40 min.
4. Take off the toner and rinse briefly.
5. Pour water in the tray (without any toner) just sufficient to cover the print and let it rest for approx. 40 min. I use some glass weights to keep the paper at the bottom of the tray. It will get more neutral tonalities during this stage.
6. Wash it for approx. 3 min. and let it dry.

During and after drying it will continue to get more neutral tonalities and darker blacks for 1-2 days, probably as the rests of toner from the fibers of the paper still work. After approx. 2 days it gets it's final tonalities and won't change anymore.

I consider adding a final stage of clearing (the traditional Pt/Pd clearing baths and final wash) after it gets its' final tonality, but probably it's not really necessary.

There are two things going on that can affect the tone/density in that way.

The first is humidity of the paper during exposure. With Vandykes (and Argyrotypes) dry paper will give you a slow print that won't tone well, no matter how long you keep it in the toner bath.

A humid paper on the other hand will print faster and toning will shift the color much more. But it's critical that the paper doesn't get dry between the start of exposure and the first clearing bath.

The other thing is toner type and timing. I haven't had any luck with Au/thiocarbamide before fixer. It works ok after fixer with only a little bleaching of the highlights, but I prefer other toners for Vandykes.

If your goal is to make Vandykes with neutral tones I suggest finding a way to humidify the paper and keep it humid during exposure. And if you want to tone before fixer, why not try Au/bicarbonate toner. IME it behaves much better.

For a 13x18 negative use:
70ml dH2O + 0.7g NaHCO3 + 25gt 1% AuCl3

 

[Dan Pavel]

I suspect this has more to do with the humidity of the paper reaching equilibrium.

This could be the case. I've ironed the last test and yes, it got more neutral and darker.

A humid paper on the other hand will print faster and toning will shift the color much more. But it's critical that the paper doesn't get dry between the start of exposure and the first clearing bath.

I couldn't find a convenient method to expose a still-humid paper without destroying the negative. A thin transparent foil between the negative and the paper will reduce the sharpness of fine details in the image and I avoid it.

Conversely, if the print is fixed again post toning, then may be it won't develop darker/more neutral tonality and match more closely the print that was toned before fixing.

I like the after-fixing toning colors and blacks more and I want to keep them. That's where I'm not sure what's the best to do: to fix and wash it again, to only wash it again or to add a final stage of Pt/Pd standard clearing/washing. I'm thinking of the Pt/Pd standard clearing/washing because I've managed to recover some older Pt/Pd prints which have turned a little yellow in the highlights this way. I even made some tests by exposing under strong UV light for 1 hour some completely finalized prints that were sensitized with a Ferric Ammoniums Citrate sensitizer. They got yellowish highlights but after a standard Pt/Pd clearing/washing they recovered nicely. I exposed them again for 1 hour to UV light and they didn't got yellowish highlights anymore. That's why I am considering a final stage of Pt/Pd standard clearing/washing.

P.S. What is the Pt/Pd Chiba process, by the way?

That test was for the Pt/Pd black layer of a CMYK Chiba process that I have worked on in the last year.