>I posted an item earlier on the experience I had of trying out Herschel's
>experiment in class of exposing paper coated with ferric ammonium citrate and
>developing it in gold chloride ( hydrogen terachloroaurate ). The result was
>beautiful, deep blue blacks and blue greys. But I have not been able to make
>another as good. I have made others but you use a lot of expensive solution
this
>way
I have always hesitated to try processes that require the noble metal salts
in the developer. It sounds like a totally impractical situation. You never
know the state of the developer, that is, has the gold exhausted, and the
risk of contamination, etc. I really am looking at the commercial aspects
of these processes and this one would be hard to sell, although I know you
were looking at it from the experimental side of things.
Any thoughts on why gold sometimes produces a red/blue tone and at others a
black/blue tone. I developed a gold toning system for pt and pd prints and
produced a couple beautiful midnight blue/black prints on pure pt prints. I
may have used a virgin developer that had never developed palladium but only
platinum, as this was before I was aware that the smallest amount of pd in
the developer prevented platinum from going neutral black. The pure golds
I've produced with the Ziatype system are purple in color and I'm wondering
if thepalladium in the acid developing bath is kicking in the red. One more
thing to try.
>I have also tried substituting 1% gold chloride for the platinum in the classic
>platinum recipe; it works but you need a negative of a limited range of tone.
>Adding one drop of palladium chloride 20% solution to the sensitiser
produces an
>image with pinkish high lights, that some like. I included one of the prints in
>the recent Melbourne and London alt photo shows. It was listed in the
catalogue
>as a 'pterigold' print :-).
The Pterigold print. Groan........... Ok, it's a fun name! Pteriauric?
Ptsulligold? Naw, doesn't work.
>
>I am about to try John Rudiak's variation which should give greater
stability to
>the reaction and a more powerful image as it uses about a 20 % gold solution.
20 % gold chloride. Ouch. Up in the $200.00 range for 25 mls.
I can see it now. Galleries will begin assaying prints to determine their price.
Dick Sullivan
Bostick & Sullivan
Santa Fe, New mexico