Comments and question about toning.
As many of you know I am a strong proponent of toning vandyke and kallitype prints for maximum permanence. If not toned these type prints have very limited resistance to some of the things that cause print to fade and self-destruct.
At this point I am involved in a research project with the folks in photograhic conservation at the Getty. Preliminary spectra analyis has confirmed what I have believed for quite some time to be the case, i.e. that toning a vandyke or kallitype print with palladium or platinum results in replacement of the silver by the more noble metal.
The toning formula used for the tests was 5 grams of 20% palladium chloride solution plus 5 grams of citric acid in one liter of water. Just enough toner was used to cover the print, which was toned in a flat bottom tray. That turns out to be about 50ml of solution for a 5X7" print.
What the tests showed was that the efficiency of toning in terms of replacment of the silver with palladium or platinum is time dependent, i.e. a toning time of 20 minute results in a much higher percentage of replacement than toning for 5 minutes. This leads me to a question that I hope some of the chemists on the list might be able to answer. How might one adjust the formula above to accelerate the toning action?
Gadget Gainer, PE, Jorge, Kirk, are you out there? I would really appreciate some comments from you folks on this.
Last edited by sanking; 11-12-2005 at 01:25 AM. Click to view previous post history.