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Re: development for alt-process
shannon stoney wrote:
> Sorry to bother you, but the guideline in your guide, to wit:
> ...
> didn't work for me. My negatives were way too dense. So, I was looking
> for another rough ballpark guideline. ...
The proper film development time will be related to several factors
aside from the film and developer selected.
The lens used can make a dramatic difference in contrast.
The exposure can have recipricosity effects also necessitating a change
in development.
The particular printing process including the various materials and
techniques can all influence what should be the development time for the
"ideal" "normal" negative.
With alt-processes like Pt/Pd and Cyanotype, there is no standardized
grading such as with gelatin silver papers, so one should make an
additional effort to understand the relationships of materials and be
able to compensate with adjustments to the negative.
On contrast control, there are many contrast agents and other methods to
alter contrast in the Pt/Pd print. But as other Pt/Pd printers can
confirm, this way of adjusting contrast can differ from that of
adjusting the negative. For example, the contrast agent Potassium
Chlorate seems to adjust contrast mainly in the higher values rather
then uniformly throughout all values.
Spending the time to make negatives that are too contrasty, or not
enough contrast, or too dense, or too weak in a controlled manner can
provide the experience and understanding of just what happens when a
negative is exposed and developed. And importantly, this experience can
provide insight into how a negative can be manipulated so as to provide
desired results with the selection of printing materials and process.
The important piece of information to find is: what does one want in the
print. Working backwards from that one should be able to determine the
negative development time. Since one has to start somewhere, such as
with a negative from the camera, it really does not matter what initial
development time is used. Because it is very highly likely that the
time will either be too long or too short. However, when several times
are used, the point of "ideal" time can be ascertained. It is either
crossed or extrapolated from that initial set of times. Then several
more times are tried which surround the estimated "ideal" time. This
set provides not only the "ideal" time but the neighboring times which
can be used as appropriate nuance is desired or warranted.
One might surmise that just as one should be flexible with the mixing of
a coating solution, so too they should be flexible with the negative
development time.
--
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/