From: Sandy King (sanking@clemson.edu)
Date: 04/10/02-11:17:43 AM Z
Katharine Thayer wrote:
>
>Wait a minute! These are *pyro* negatives! I missed that completely the
>first time I read this. I told David it looked like overexposure to me,
>but it seemed odd that by his description it sounded like he was getting
>overexposure at a minute or an hour; this information makes it make more
>sense. I think we're back to that spectral density question, and how
>gum vs platinum responds to colored "filters." and I also think the
>answer to David's question is to start over with a new set of negatives,
>develop them in a conventional developer, and see what happens.
I can not know if the staining caused by Pyro is the problem child in
this instance but in general Katharine is right to raise the question
about the spectral density of a Pyro negative.
In my work with carbon and kallitype I have found that image stain
with well-exposed and developed negatives does not appreciably
increase printing time. However, this is not true of over-exposed
negatives, especially with films that have a very high natural b+f
such as HP5+ and BPF. The problem can be even more aggravating when
using films like HP5+ and BPF that are slightly outdated. As we know
there is really no way to store high speed films so as to completely
eliminate cosmic rays that over time will lead to fogging. How much
depends on quite a number of factors but from experience it is
evident to me that medium and high speed films like BPF, TRI- and
HP4+ will develop fog over time even when stored frozen.
Which brings me to the main point of the present message. Although it
was discontinued many years ago I have kept in frozen storage for
quite some time a cache of the late and great Kodak Super-XX film in
11X14 and 12X20 size, in anticipation of one day using this film for
my own "Moonrise over Hernandez" equivalents. However, since that has
not happened, and much time has passed, I decided a few weeks ago
that I needed to use the film now rather than wait for its price to
start increasing again as a collectible, which likely won't happen
until the year 2075, if at all.
OK, so I loaded my 12X20 film holders with the precious commodity,
expiration date of October 1989, and over the past two weeks exposed
quite a number of sheets of film. What I found was that the film,
even in frozen storage, had developed a base fog on the order of
about log .50. The first few sheets of the film were developed in my
Pyrocat-HD formula, which with most films gives a lower b+f than
either PMK or Rollo Pyro (ABC+). The result was an extremely high
b+f, in the range of about log .90, indicating that the staining had
added about .40 of overall or general stain to the basic image stain.
Results with D76 1:1 were much better, as even with the extended
development needed to bump the contrast of this old film the b+f did
not exceed .55.
Which leads me to make the following points.
1. The significant increase in printing time that some people
complain results from the use of staining developers most likely
results from one of the following causes, 1) use of fogged film,
and/or overexposure by a stop or more.
2. When working with outdated film (or film that may have developed
fog from being subjected to high temperatures), especially one that
has a high natural b+f even when fresh, the use of staining
developers should be avoided because this may cause indecently high
b+f.
Sandy King
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