Re: Van Dyck and Kallitype
Title: Re: Van Dyck and Kallitype
Most of the steps that we would take in Pt./Pd. printing to
improve Dmax also apply to kallitype. That specifically includes both
the oxalic acid soak and double coating. But all papers don't need the
oxalic acid soak, and double coating improves some only slightly --
same is also true with Pt./Pd. One of the disadvantages of double
coating is that it makes the print harder to clear.
Sandy
Jordan,
Maybe Sandy can chime in here about the double coating, and I may be
drawing an erroneous comparison, but sometimes with PT/PD double
coating improves the smoothness of the print and DMax because the
first coat neutralizes the paper and thus the second coat is laid down
on a slightly acidic paper. Have you tried presoaking the paper
in Oxalic Acid, or Sandy, would you not recommend this?
Best Wishes,
Mark Nelson
Precision Digital Negatives -
The System
PDNPrint Forum at Yahoo
Groups
www.MarkINelsonPhoto.com
In a message dated 9/25/06 10:07:41 AM, jwosnick@fastmail.fm
writes:
I'm a bit late to this party, and I may be hijacking the thread a
little, but I find it interesting that Kallitype doesn't need to
be
double-coated. I like the results I'm getting with Van Dyke, but
the
double-coating is killing me, as it seems to lead to blotchiness
on
the prints (I've been using Stonehenge Rising, Fabriano Artistico
and
Arches Platine).
I'm toying with the idea of trying Kallitypes. It's my
understanding
that if I have what I need for VDB, all I really need for Kallitype
is
iron(III) oxalate. But I'm a little edgy about the cost and risk
associated with buying the commerical material.
There is an experimental technique in chemistry called potassium
ferrioxalate actinometry, which allows one to make an absolute
measurement of light (number of photons per cm3 per second). It
basically uses the "Kallitype/Pt-Pd" reaction, but instead
of reducing
Ag(I) or Pd(II) or Pt(II) at the end, the ferrous iron is allowed
to
form a coloured complex. The actinometry mixture is made by
combining
a carefully titrated solution of iron(III) sulfate with a six-fold
molar excess of potassium oxalate solution. In theory, this could
also
be used to avoid the need for ferric oxalate (ferric sulfate is
cheap). I wonder if anyone's ever tried it?
Jordan
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