Staining when toning Van Dyke Brown prints with Palladium toner ...

[largo]

Hi there !

I made a few new attempts at toning Van Dyke Brown prints.

Toning with gold-thiourea (L.P. Clerc formula) worked very well, but the VDB print toned with palladium got severely stained : the paper base became all yellowish... as you can see on the right in this picture (left sample is untoned, middle sample is toned with gold/thiourea) :

Note that I tone the print after clarification and before fixing them, as recommended in several books (Donald Nelson, Dick Stevens, ...)

I have observed that the staining appears just when the Pd toned print is immersed in the fixing tray ... The fixer is a plain 4% sodium hyposulfite solution

Here is how I prepare the palladium toning solution :

1. I pour 200 mL of demineralized water into a beaker.
2. Using a precision balance, I weigh out 2 grams of citric acid and pour into beaker
3. Using a glass stirring ring, I stir until the citric acid is completely dissolved in the beaker. The result is a 1% w/v citric acid solution.
4. I add 10 drops of 15% w/v sodium tetrachloropalladate(II) stock solution.
5. I mix with the glass stirring rod

This Pd toning solution is yellowish, but I can observe that the paper base remains white in this toning solution (here tested with a simple piece of Bergger COT320), even if left during 10 minutes in the toning solution :

It is only when I immerse it in the fixer tray that the staining occurs all of a sudden :

Do you have an idea of what could go wrong ?

Thank you very much for your helpful comments !

Best regards,

Loïc

 

[cliveh]

You could try toning after fix and wash.

 

[koraks]

You could try toning after fix and wash.

That would be a good thing to test. Although Van Dyke really shouldn't stain this badly when toning is done before fixing, regardless of what toner is used.

The first thing that comes to mind is that perhaps somehow silver sulfide is formed in the toning bath with the carried-over chloropalladate somehow acting as a catalyst. If so, I'd expect that thorough washing after toning and before fixing should solve the issue.

Maybe @fgorge or @nmp could comment on this.

 

[largo]

That would be a good thing to test. Although Van Dyke really shouldn't stain this badly when toning is done before fixing, regardless of what toner is used.

The first thing that comes to mind is that perhaps somehow silver sulfide is formed in the toning bath with the carried-over chloropalladate somehow acting as a catalyst. If so, I'd expect that thorough washing after toning and before fixing should solve the issue.

Maybe @fgorge or @nmp could comment on this.

Guys,

I might have found a solution... Here is what I've just changed in my workflow :


After toning, I thoroughly wash the print in running tap water during 5 minutes at least (just like you also suggested)

Then, when I immerse the print in the fixer (5% hypo), it still gets a bit yellowish (the paper base of the whole print), but less than before...

But what really did remove this yellowish staining is the hypo clear wash : When I immersed the fixed print in a 1% sodium sulfite bath, I observed the the staining got a bit removed... So I added more sodium sulfite (up to a 3-4% solution I guess), and voilà! the paper base is plain white !!

 

[FotoD]

I would try an alkaline bath between toner and fixing. A bath in 4 g/l sodium carbonate (or bicarbonate) works well with Pt-toner.

Then wash for several minutes in tap water until you are sure all toner is gone, before fixing.

Even if you found a fix, it's better to avoid the stain in the first place if possible.

 

[koraks]

Even if you found a fix, it's better to avoid the stain in the first place if possible.

I agree. The print may still yellow as it ages.

An alkaline wash will help the paper to swell, making the wash quicker/more effective. I can imagine it helps to draw out the toner remnants quicker.

 

[largo]

I would try an alkaline bath between toner and fixing. A bath in 4 g/l sodium carbonate (or bicarbonate) works well with Pt-toner.

Thanks ! Where did you get that info that a 4g/l sodium works well with Pt-toner from ?

 

[FotoD]

Just from using it. It's not a critical amount, take it as a starting point if you want to try it. I've seen both lower and (significantly) higher concentrations suggested.

 

[nmp]

This would make sense. Sodium thiosulfate is a known reducing agent so it may be not be surprising if there is a residual toner, it gets converted to metallic Pd or Pd sulfide (as it happens with silver nitrate - the reason behind the necessity to remove it or otherwise convert it to halide before fixing in salt printing.) Easy to check - add a drop of the toner to a bit of fixer, see what happens.

:Niranjan.

 

[largo]

Easy to check - add a drop of the toner to a bit of fixer, see what happens.

That is indeed exactly what I did yesterday : adding a few drops of hypo fixer to the palladium toning solution, and its color has become a more intense yellow, probably due to the formation of sulfides... :



And here is my latest VDB print toned in Palladium, with the previous strip stained on the right for comparison :

 

[FotoD]

That print looks a lot better!

Are you adding any alkali to your fixer? If not, maybe that would help keeping any residual Pd-toner inactive during the fixer bath.

If this drop test was with plain hypo, you could repeat it with 0.25% sodium carbonate added to the fixer to see if an alkaline fixer bath makes a difference. (I've used 3% hypo + 0.2% sodium carbonate)

 

[largo]

That print looks a lot better!

Thanks !

Are you adding any alkali to your fixer? If not, maybe that would help keeping any residual Pd-toner inactive during the fixer bath.

No. I indeed used to add 2 grams of sodium carbonate per liter of hypo fixer, for regular untoned VDB prints. But I remove the sodium carbonate from the fixer formula when toning using gold-thiourea L.P. Clerc formula... Now I think it is needed when fixing a print toned with Palladium, like you say

If this drop test was with plain hypo, you could repeat it with 0.25% sodium carbonate added to the fixer to see if an alkaline fixer bath makes a difference. (I've used 3% hypo + 0.2% sodium carbonate)

yes, I'll post my results here by the end of the day...

 

[nmp]

Thanks !



No. I indeed used to add 2 grams of sodium carbonate per liter of hypo fixer, for regular untoned VDB prints. But I remove the sodium carbonate from the fixer formula when toning using gold-thiourea L.P. Clerc formula... Now I think it is needed when fixing a print toned with Palladium, like you say



yes, I'll post my results here by the end of the day...

I would add a drop of Pd to the fixer. Why waste precious toner for the test?

:Niranjan.