Clearing Kallitypes - Disodium EDTA vs Tertrasidum EDTA vs Citric Acid

Great work @cirwin2010. The next time I make a Kallitype, I'll take another look at Citric Acid clearing...

cirwin2010 said:

I was wondering about that. Would potassium ferrocyanide + potassium bromide bleach reduce the palladium to a palladium salt like it does for silver? I wasn't sure if palladium even could react with the bleach.

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Ferrocyanide will oxidize metallic Pd(0) resulting in Pd(II) and PdBr2 is insoluble in water. Thus, I imagine that a rehalogenating bleach would work similarly on both a silver and a palladium print as far as the chemistry of bleaching goes.

However, is according to Google a dark brown or black or gray or reddish-brown (depending on exactly what, I can't tell). This is in contrast to silver bromide which is pale yellow. Thus, I am not sure that one would visually notice the 'bleaching' action on a palladium print.

But then what?

cirwin2010 said:

I did take one of those bleached prints and redeveloped it in sodium sulfide. Normally with silver this makes silver sulfide. Could I have made palladium sulfide?

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This is idea might actually work for the "then what"!

PdBr2 should react with sulfide to make PdS which is both insoluble and black in color.

Lastly, I must say... why bother with any of this?

If you want to stabilize/protect a kallitype why not just use the tried and true methods for platinum or gold toning?

fgorga said:

Ferrocyanide will oxidize metallic Pd(0) resulting in Pd(II) and PdBr2 is insoluble in water. Thus, I imagine that a rehalogenating bleach would work similarly on both a silver and a palladium print as far as the chemistry of bleaching goes.

However, is according to Google a dark brown or black or gray or reddish-brown (depending on exactly what, I can't tell). This is in contrast to silver bromide which is pale yellow. Thus, I am not sure that one would visually notice the 'bleaching' action on a palladium print.

But then what?



This is idea might actually work for the "then what"!

PdBr2 should react with sulfide to make PdS which is both insoluble and black in color.

Lastly, I must say... why bother with any of this?

If you want to stabilize/protect a kallitype why not just use the tried and true methods for platinum or gold toning?

Click to expand...

Yeah I guess I'm losing the plot here. I tried bleaching the print to see how much palladium was in the print as I thought it was stable enough to not bleach away like the silver. Clearly that idea was flawed.

I bought a bunch of palladium since I thought I liked the color, was adding stability, and it was cheaper than platinum.

Well I've established that much of the color change I thought I saw was actually from the citric acid in the toner affecting the image. Also palladium is clearly not as stable as platinum as established. So yeah, to your point, what am I doing again?

I still want to figure some of this out though. Does the palladium actually change the print color? How can I tell how much I am toning the image if I can't see it? What is the best way to clear iron from the print without losing dmax?

Maybe another process would have been easier, but Kallitype is cheap and I'm stubborn.

Cor said:

Just in the middle of a Kallitype printing session (you know why, Koraks....), my procedure is based on Sandy King's protocol: double coat with FeOX and AgNO3, develop in 20% Na Acetate, rinse with water with a pinch of citric acid, than clearing in 3% citric acid, rinse again, tone with Palladium (single shot), wash with plain water and 2 bath fix in basic Hypo. Cannot say I have observed bleaching.

good luck,

best,

Cor

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Sorry for the clutter, but i made a mistake, I use 20% Sodium Citrate as developer, not Sodium Acetate, the better option anyway as seen above,

Best,

Cor

(printing Kallitypes right now and looking carefully at the 3% Citric Acid step (I do that step for 1-2 minutes) I see the solution turning slightly milky in colour, which I assume to Sliver Citrate. De highlights clear up but do not bleach, although that is hard to see)

If you go to the alternative gallery on my website and in the 2d to last row on page 1 you'll see three prints side by side of the Methodists church in Bodie, untoned and palladium-toned VanDyke Brownprint, and lastly an untoned kallitype.

In a post from a previous thread, Sandy King makes this interesting point:

"some small amount of dichromate is needed with kallitype, even with negatives of optimum DR, which is about 1.8, to completely clear the paper. The same is also true with straight palladium"

Though this point (that dichromate is required for complete clearing) is not made in his excellent article on Kallitype working procedure, Sandy has discussed it also in another post:

"dichromate also plays an important role in clearing and without at least about 2ml of a 5% dichromate solution per liter of developer it will be very difficult to get full clearing. This is also true with palladium printing."

This could be something OP might want to try. This could potentially help reduce the clearing time (OP mentions 10 minutes which is long, Sandy recommends four minutes or less) and avoid bleaching.

After some more testing, research, checking my test strips after drying, and some more thought, I've come to the following conclusions.

1. Sodium acetate developer is just a bad time. Not only is in finicky to use by being inconsistent (fresh vs used), it also just makes the paper very difficult to clear.
2. Sodium citrate is far superior to sodium acetate when it comes to consistency and by being far easier to clear the paper. In fact there is next to no yellow color to the whites after coming out of the developer.
3. Citric acid at 3% is the best at clearing iron stain, but will also "bleach" the silver. It will also yield brighter highlights (see item 6)
4. Citric acid (tested down to 0.5% dilution) will alter the color of the print.
5. Clearing too long in 3% citric acid will cause more bleaching in the fix and cause a splotchy look in the highlights.
6. What I am seeing in the whites of my sodium citrate prints does not appear to be iron stain, but perhaps silver stain/fog. This likely gets removed by the citric acid "bleaching" it away.
7. Tetrasodium EDTA yeilds the best blacks for sodium citrate prints as it does not bleach the image. Highlight and midtone density changes can be calibrated out.

Questions I have yet to answer:
1. Is a clearing bath even necessary for sodium citrate developer or will a tap water (7ph) rinse work?
2. Is the "fog" I'm seeing in the highlights just a product of the sensitizer reacting with the paper or are my led lights slightly exposing the paper? Arches Aquarelle cold press is worse than Legion Revere Platinum despite requiring ~2x more exposure.
3. Is citric acid bleaching paper dependent? Arches Aquarelle cold press may not be as affected, but more testing is required.