From: Sandy King (sanking@hubcap.clemson.edu)
Date: 05/31/01-08:12:08 PM Z
In an off-list message someone asked me to comment on my use of platinum as
a toner. I have used platinum as a toner for kallitype prints, and most
recently, with home-made POP paper (after Liam Lawless's article in
Post-Factory). My experience with both of these processes is rather limited
so follow-up information would be appreciated.
1) Kallitype. This is one of the variants of the silver/iron processes in
which the image does not not print out but must be developed out. Since one
can with the correct choice of developer make kallitypes in a wide range of
colors they are not toned for color control. However, for maximum image
stability a kallitype should be toned. Gold and platinum are probably the
best choices for this, and of the two I have had much better and more
consistent results with platinum. I always tone after clearing and before
fixing. The toner that I use is made up of 5ml of a 20% solution of
potassium chloroplatinite, sold by Bostick and Sullivan as platinum
solution #3, and 5g of citric acid to a liter of water. A liter of solution
has very great capacity, up to and pehaps even more than 12X20 prints in my
experience. My favourite developer for traditional kallitype is a 30%
sodium citrate solution, which before toning gives a rust-brown image. A
few minutes in the platinum toner turns the color to a rich platinum color,
indistinguishible in every respect from a real platinum print.
2) Home-made POP. I recently worked a bit with the home-made POP process of
Liam Lawless. I followed Liam's directions exactly, exact for the
substitution of ammonium chloride for sodium chrolide and the use of a 250
Bloom ossein gelatin instead of the ones he experimented with. I applied
the emulsion with a brush, and double coated for maximum Dmax as Liam
suggested. The results were excellent and Liam is to be congratulated for
the clear and precise directions and for all the experimentation he did
before publishing the article. Some experience is requried in working with
POP papers to get the right exposure because of the fact that the image
must be over-printed by 3--4 steps because it bleaches out on fixing (and
at a different rate according to formulation of the fixer). The color
without toning, a rust/brown/red is very unattractive to be so toning for
control of color is important. Toning can be done with POP either before or
after fixing, but I chose to do the former, and what I finally settled on
was a split-toning using a traditional gold borax toner, followed by toning
in the platinum toner I used for kallitype. This gave a very attractive
black with a hint of purple/eggshell. However, it is very hard to get
consistent color with this split-toning technique as the strength of the
two toners is being constantly depleted in ways which are not readilly
apparent.
I hope this is of interest to some, and I would certainly like to hear of
the experience of others in toning kallitype and/or POP papers, either
home-made or of the commercial variety.
Sandy King
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