Re: Polaroid Pos/Neg film/Zone System

Keith Schreiber (KEITH@server.ccp.arizona.edu)
Tue, 11 Feb 1997 19:09:39 -0700

Regarding the suitability of Polaroid Type 55 P/N film for
alt-process work, a couple years ago I printed 2 series of images
made on Type 55 film. The prints are platinum/palladium on Masa
paper. Ratio of pt:pd was 1:19 and the ferric oxalate sensitizer used
in the A:B method (with 0.6% K chlorate in B) was in the ratio of 5:1
or 4:1. Had I used more Pt and less Pd even less chlorate would have
been needed. Prints were developed in plain potassium oxalate.

My point is that Type 55 can be used successfully with pt/pd and
other alt-processes as long as it's not underexposed. I believe there
is also limited control in development though I base this only on
"anecdotal" evidence -- I haven't tested it rigorously. I make most
of my negs 8x10 these days and if Polaroid made Type 55 that size
I'd use it.

As to Terry's comment about the zone system elsewhere in this
thread, I think he is mistaken. The zone system, the use of
step-tablets, or any other method of contrast control, can be
applied to any photographic printing process. It's a matter of
calibrating your film exposure and development to fit whatever
printing process you are using. That the zone system may have been
designed for use with commercially manufactured gelatin silver paper
is irrelevent. I think this sleeping dog was discussed at great
length last year so maybe we should let it lie.

Regards to all,
Keith

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Keith Schreiber, Rights and Reproductions
Center for Creative Photography, University of Arizona
PO Box 210103, Tucson AZ 85721-0103
Fon: 520-626-5164 Fax: 520-621-9444
Email: keith@ccp.arizona.edu
WWW: http://www.ccp.arizona.edu/ccp.html
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