Re: Silver chloride contact printing papers - not AZO

From: Richard Knoppow ^lt;[email protected]>
Date: 01/27/04-05:29:50 AM Z
Message-id: <>

-----Original Message-----
From: Judy Seigel <>
Sent: Jan 26, 2004 10:00 PM
Subject: Re: Silver chloride contact printing papers - not AZO

There is another silver chloride contact paper besides AZO... It's
the Centennial Gelatine Chloride Printing-Out Paper sold in this country
by Chicago Albumen works.

In fact I just finished editing (5 pages, small type) a dialog between
John Yang and John Dugdale about their shows at John Stevenson
(concatenation of Johns again). Yang's "Mount Zion: Immortal Portraits" in
2001 was all on the chloride POP paper. John D's just-closed show had
about 6 of them, plus albumen & cyanotype.

The most discussion was Yang on the nuances of the gold toning, which
control the color, assuming you've eaten the right breakfast and the
temperature, alkali, timing, exposure, and negative are right. John D.
wanted the "secret" of the "pink" highlights, got that & a lot more. Will
be in P-F #9, if I live & my computer relents.

Chicago Albumen Works is (413) 274-6901,

e-mail, and

PS. I'm a pretty tough customer with silver gelatin these days, but I
willingly reveal that those gold-toned prints are exquisite.


   Judy, its important to distinguish between printing out paper and developing out paper. Centenial POP is a printing out paper, Azo is a developing out paper. While both have silver chlororide in their emulsions (I am assuming this about the Centenial paper) the emulsions are otherwise different. The image on POP is produced directly by the action of intense light on the emulsion. The image of a paper like Azo is produced by chemical action on a latent image. There is also a vast difference in speed. Azo, while much slower than enlarging paper, is still printed with low intensity artificial light. Typically a 40 to 60 watt incandescent lamp at a couple of feet will print in about 30 seconds. POP, like other printing out processes, requires very intense light, sunlight or artificial light of similar intensity. Printing time is a few minutes in direct sunlight.
   In addition, POP has a self masking property which developing papers do not. As the paper prints the increasing density of the shadows tends to slow down further build of of density by blocking some of the light. This gives POP papers a very long "toe" compressing the shadows. This allows the printing of rather high contrast negatives because the highlights can be printed in without loosing shadow detail. Azo, prints like any other developing paper, no masking.
   As I mentioned before all of the major manufacturers made one or more contact papers until perhaps 25 years ago. Kodak made Velox, Azo, Athena, Illustrator's Azo, Resisto, and a foldable document paper the name of which I've forgotten. Velox was blue-black and is the familiar stuff of photo finishers and beginning printers; Athena almost brown black. Ansco made two papers, a neutral and a warm tone paper (better IMHO than Kodak's) and other papers were made by Defender, Haloid, and others. All of these came in several contrast grades, single and double weight stocks, several stock tints, textures, and surfaces. All gone now but single weight, glossy, white Azo.
   I am not personally convinced that Azo makes any better contact prints than one can get using enlarging paper in a printing frame, but there are enough who do think so to keep it alive.
   So, here I am with two 8x10 contact printing boxes (Agfa and Morse), talk about your antiques. What facinates me is that so many photographers now don't know what these are. When I strarted out in photography (and you too probably) contact printing was the only alternative if you were not rich enough to afford an enlarger.

Richard Knoppow
Los Angeles, CA, USA
Received on Tue Jan 27 05:30:03 2004

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