From: Sandy King (sanking@clemson.edu)
Date: 03/10/03-06:41:48 PM Z
Chris wrote:
>
> I may be sticking my neck out here--no, not *may*, but *am*--but I'll
>offer my research for whatever it is worth on solarizing/bronzing. The
>research is from as far back as late 1800's to now on the alt list. It
>seems no one has the definitive answer for the issue, probably because
>there are a number of variables.
>
> It would be nice if someone could quantify this bronzing effect. It
>must depend on more than just over exposure. I have a particular negative
>that requires almost a three hour exposure and the uncovered edge coating
>does not display any signs of bronzing nor solarization.
What you say about bronzing/solarizing depending on more than just
over-exposure may be true but I have never experienced it with either
kallitype (including Vandyke) or salted paper except as a result of
over-exposure.
It is important to remember that bronzing and solarization, when they
take place, are always either in the shadow areas of the print or in
the borders of the negative (or in the surrounding areas that were
sensitzed but not exposed when printing with no mask around the
negative). Although I don't understand the mechanism of why
bronzing/solarizing take place, in my experience it only happens when
the density range of the negative is much more than the exposure
scale of the process. This means that by the times the highlight are
sufficiently printed the shadows will have received from 2X and more
exposure than required. In theory you could have a very dense
negative that might require days to print but which nonetheless has a
density range that matches the ES of the process. You would not see
solarizing or bronzing in this case, at least not within the masked
image area of the print.
I have observed that the result of great over-exposure is quite
different with kallitype than with salted paper. With kallitype
over-exposure usually results in a true reversal of image densities
because at a certain level of exposure the shadow values actually
begin to lighten. With salted paper the result is bronzing, but with
no reversal of tones.
With both kallitype and salted paper toning, especially with
palladium or platinum, restores shadow values and largely eliminates
tonal reversal caused by solarization.
Sandy King
This archive was generated by hypermail 2.1.5 : 04/22/03-02:37:25 PM Z CST