Clearing Kallitypes - Disodium EDTA vs Tertrasidum EDTA vs Citric Acid

[Andrew O'Neill]

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

 

[fgorga]

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.

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?

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?

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?

 

[cirwin2010]

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?

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.