Toning kallitypes and vandykes

I posted the following message over on apug.org but so far have
gotten zero response. Hope someone here can offer some advice.

Basically the situation is this. I interested the folks in
photographic conservation at the Getty with the issue of toning
kallitypes with pallaidum and platinum, specifically. Preliminary
spectra analyis in their lab has confirmed that toning a kallitype
(and I believe the same would apply to vandyke) with palladium or
platinum results in replacement of the silver by the more noble
metal, adding much permanence to the print.

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,
and I did toned 5X7 test samples for 2.5, 5, 10 and 20 minutes, using
just enough of the toner to cover the surface of the print in 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
the percentage of replacement of the silver with palladium 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. Does anyone have any idea how I might adjust the toning
formula formula above to make it faster acting?

Sandy
Received on Sun Nov 13 22:27:17 2005