> ... Does k chlorate always cause "graininess"?
For the first two years that I worked in pt/pd I used the A:B
K chlorate method for varying contrast and used the sun as my UV
light source. I didn't have any grain problems until moving indoors
in order to be able to work round the clock. I think that subesquent
grain problems are more likely a coincidence and not a consequence of
the change in light source as I have found other factors e.g.
humidity, to be at least as important. Also of course the more
chlorate is used the greater the likelihood of encountering grain
problems. Someone else suggested that grain can also be a problem
with the dichromate method. While this may be so for some it has not
been the case in my personal experience. Just this afternoon I did a
comparison of the 2 methods using an 8x10 negative previously printed
by the chlorate method. With the chlorate method, a mixture of
0.6ml A + 0.4ml B + 1.0ml Pd on Cranes Platinotype was exposed for
7 minutes at 8 inches to my AQA tubes, and developed in K oxalate.
With the dichromate method, I used my now standard mixture of
1ml ferric oxalate + 1ml Pd + 1 drop H2O2, same paper, same exposure,
developed in K oxalate #7 which has 64 drops of sodium dichromate per
200ml of K oxalate (maximum contrast). The resulting prints showed
the expected grain from the chlorate method but little if any grain
with the dichromate. With this particular print I think I prefer the
chlorate version (this is not usually the case).
Someone in another post (Terry King, I think) said something to the
effect of the best of these methods is neither. In other words, that
in the best of all possible worlds, contrast enhancement of any flavor
should be unnecessary, and with this I wholeheartedly agree. With
negatives that fit perfectly (or nearly so) the tonal scale of the
process the chlorate vs dichromate argument is moot. And if this can
be achieved in original camera negatives, as opposed to via
interpositive or internegative, then better yet.
I'll stop here for now. Gotta get some sleep.
Keith
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Keith Schreiber
Rights and Reproductions
Center for Creative Photography
University of Arizona
Tucson, Arizona 85721
Fon: 520-621-7968
Fax: 520-621-9444
Email: keith@ccp.arizona.edu
WWW: http://www.ccp.arizona.edu/ccp.html
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