Table of Contents

Brush-Toned Still Lifes

Jewish North Africa


Vestiges of Rome

Re-Visioning Antiquites

Portfolios Index

Images of Jewish Morocco I '93

Jewish Sites of Cairo and Alexandria '94

Images of Jewish Morocco II '95

Tunisia '97

About the Jewish North African Portfolios

About the Prints

About the Artist



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Introduction to some technical aspect of
Gelatin Silver Chloride Printing-Out Paper


All of the prints on this site are printed on a paper called gelatin silver chloride printing-out paper, a 19th century print making process that I have adapted to contemporary uses. First introduced in 1884 it has been on the market longer than any other manufactured paper in the history of photography--an astounding fact when one realizes how intensely competitive and susceptible to change the photographic market is.

Photography, practiced as an art form, differs from painting and sculpture in that it is fundamentally an industrial form--its processes and materials exist because they are of current commercial utility, and it is their market use that provides the economic viability of their manufacture. Once surpassed by a newer, more advantageous image-making process, they are quickly discarded as a market liability and their very means of production are often disassembled. Today we are in an accelerated phase of this part of the cycle, with digital quickly overtaking the market share of chemical-based photographic processes, especially in the area of color photography.

Ironically, the earliest photographic print processes can still be practiced, because the papers which they used were coated and sensitized by hand, and the chemicals and materials for this are still available, whereas later processes of the 20th century can no longer be practiced once their means of production, the factories that produced their materials, have been disassembled. Photographic processes which have been discarded by the mainstream industry, yet due to their particular characteristics can still be practiced today, are called historical processes. The printing-out paper which I use is a historical process. The paper is still manufactured because it has been able to maintain a slight niche in the market for historical papers applied to artistic uses. It is made by a company that has come to specialize in manufacturing in small quantities papers that the larger market has discarded.

In order to understand the technical layer that underlies the aesthetic of these photographs, as well as to understand their value in relationship to the contemporary processes which currently dominate the market, it is important to understand something of the history of photographic papers as well as the particular print qualities each of these processes renders as they apply to POP

Printing-Out Paper vs. Developing-Out Paper / Contact Papers vs. Enlarging Papers

There are two major evolutionary branches of silver photographic papers, those processes which developed during the origins of photography and dominated the paper market for its first 65 years (from the 1840's up until 1905.) The first was printing-out papers. A very different system rapidly replaced it at the beginning of the 20th century, known as developing-out papers.

The difference between the two processes lies in how the photographic image is formed on the paper.

With a printing-out paper (the process by which all of the prints in this exhibition have been made) it is light energy alone that reduces the silver salts into the metallic silver particles that form the image. The image begins its visible development as soon as the paper is exposed to a sufficient amount of light and prior to any immersion in chemicals. With a developing-out paper (the process by which virtually all commercial black and white photographic prints are currently made) a minimal amount of light is required for exposure, and the main work of the reduction of silver particles into the metallic silver image is chemical.

The introduction of developing-out papers offered an enormous technical advantage in the development of photography by applying to paper emulsions that had been developed in the field of film. Since the requirement of light energy had been reduced to a minimum (i.e. the paper is very fast), exposure of the paper could be accomplished by projecting the negative through a lens onto the paper, and this allowed for the use of a much smaller negative which could then be projected onto the paper and thereby enlarged into images of varying sizes, thus opening the way for the use of small film and the ubiquitous compact hand-held cameras of today.

The difference between these two systems can described as 'contact printing papers' vs. 'enlarging papers'.

In comparison, a printing-out print requires up to 100,000 times more light energy to form an image, making it a very 'slow' paper in terms of exposure, so that until recently, the only practical source of exposure with such intensity was skylight. Some of these prints took up to 8 hours to expose.

Just as enlarging papers brought with them a change in cameras, working systems, and opportunity to photograph things previously impossible to capture (such as casual everyday life), contact printing papers, because they will only produce a print the size of the negative being printed, require their own working system and apparatus. Because it requires such an enormous amount of light, the image cannot be projected. Instead, the negative must be placed directly against the paper, so that a print can only be made from a negative of the same size. A much larger original negative is required, and so a larger camera. Because only view cameras will expose film of a suitable size (cameras where the image is composed and focused on a ground glass and then the film, contained in a separate folder, is inserted into the camera back prior to exposure), a tripod is required and photographing motion is limited by bulk, focusing and loading, and by the slow speed of film.

Printing-Out Paper vs. Albumen Paper

Gelatin Silver Chloride Printing-Out Paper was able to capture the market so easily once it was introduced for a number of advantages it offered over the then dominant albumen papers on the market.

The first has to do with the method by which photographic papers were sensitized.

Printing-out papers fall into two categories: salted papers and emulsion papers according to the method by which the papers are sensitized. Salted papers are intrinsically hand made, using a two step process of sensitization in which first a coating ammonium or sodium chloride suspended in an organic binder was applied to the paper and allowed to dry, and then just prior to use, a second step whereby a solution of silver nitrate was applied to sensitize it for exposure. The first photographic prints ever made on paper, those made by Fox Talbot in 1834, were salted prints used without any binder. Salt prints as a rule have little or no organic binders, so the image recedes into the paper giving it its matte appearance.

By 1855 albumen prints began to dominate the market. Albumen prints are those photographs we most associate with 19th century photography, amber-brown in tone, often faded, and with yellowed highlights, and they dominated all other 19th century processes, so much so that 85 % of the prints made in the 19th. century which survive today are albumen prints. Albumen prints are coated with a layer of binder and since it is the binder is that keeps the image suspended on the surface of the paper, the image produced is much glossier. Later much albumen paper was already being manufactured 'albumenized' with an emulsion of salted egg white solution, but the paper still required the second step of sensitization just prior to use.

Various forms of salted papers, in particular albumen papers, continued to dominate the market up until the introduction of gelatin silver chloride printing-out paper in 1884, in which the two steps for preparing the sensitized emulsion were combined into one through a manufacturing process. The advantage of the earlier salt prints was that they could be handmade in small volume and had the possibility of an enormous range of characteristics. The great advantage of the emulsion papers that replaced them was that they required no preparation and were manufactured ready for use without any prior preparation: the silver nitrate is already formed and dispersed into the emulsion during the manufacturing process, creating a paper that could simply be removed from its wrapping and used immediately.

Not only did gelatin silver chloride printing-out paper combine the two step process into a manufactured emulsion, it also shared the essential characteristics of albumen paper both of darkroom, sensitivity, and toning (its slow printing speed, contrast, processing sequence and processing chemistry). As a result, no adjustments were necessary for its use. Albumen prints have an exceptionally long tonal range and require a very dense negative and the same negatives that printed well on albumen paper printed well on printing-out paper. POP also retained the rich deep tones of albumen prints.

While albumen prints have extraordinary virtues, they also have intrinsic flaws, and printing-out paper was brought onto the market as a paper that corrected the flaws and maintained the virtues. Albumen paper has an intrinsic tendency to yellow in the highlights and to fade over time, often exacerbated by faulty fixing and washing techniques of the 19th century. It can be observed in almost all albumen prints (so much so that it is one of the means used to identify an albumen print).

From the 1890's onwards a growing distrust of albumen paper's tendency to yellow gave POP a clear market advantage. It quickly overran albumen paper's market share, becoming the dominant paper on the market, remaining so until 1905 when enlarging papers papers emerged in the lead.

Tonal Qualities of POP and the Characteristics and Effects of Toning:

While printing-out paper is a silver paper (i.e., its surface is composed of silver chloride set in a gelatin emulsion), the image that we actually see in the finished print has been converted from a silver print into an image formed of gold. This transition takes place when the prints are toned in a bath of gold chloride, and in the process of toning each silver molecule in the emulsion is encapsulated by three gold molecules. No two prints produced by POP are exactly the same. This is due largely to the toning process of the print which is very inexact. Standardization, exact duplicates, predictably repeatable results are elusive at best.

The tone of the print is affected by a large number of factors, including: ph of the gelatin binder; ph of the silver solution; density of the silver image; temperature and time of the pre wash; temperature, time, ph strength and phase of the gold toning bath; ph of the thiocyanate solution (fixing bath); humidity level of the paper during exposure and toning. This makes it very difficult to make two prints which are exactly the same, but it also makes it possible, on occasion, to produce extraordinary prints, unlike any others. The unique quality of each print has implications for marketing POP prints, as they are more like 19th century prints in this way than are modern prints which can be churned out in limitless numbers all looking exactly the same.

The very qualities of unpredictability which make POP a liability for commercial trade and which led to its discontinuation in the industry, endow it with extraordinary qualities for art, where its extremes of tonal variation are valued for the emotional resonances they are able to convey. Two prints exposed exactly the same and toned the same can emerge quite different in effect. Very minor shifts in tone will have major impact on our response to the individual print. Thus some prints are toned to be warm, and others, like Juba II, are toned almost to a black hue. Like children of the same family, differently toned prints of the same image each have their own particular personality.

POP has an extraordinary range of tone and color, from radiant chestnut to charcoal black, sometimes even in the same print. So while it is not a colour print, it is a toned print and not a black and white print. This range of coloration comes mostly from the toning process, the most critical part of the printing process and the one that ultimately gives the print its 'voice'.

Enlarged prints vs contact prints from the original negative

Each photographer has his own values for deciding on the sizes of prints. My choices are made for aesthetic reasons having to do with the specific image at hand. I have always found one particular size fits each image best, and while the original negative always produces the most sharp print (in this case an 8x10 inch print), in some negatives the information is so dense that it is lost in such a small print. A larger size brings it to life, allowing it to open up and be seen properly.

Almost all of my prints are made from either a 5x7 or 8x10 inch original negative, so the basic print size is either 5x7 or 8x10 inches. In order to make a 12x15 or 16x20 inch print, I have taken the original 8x10 negative, contact printed it onto another sheet of 8x10 film to make an interpositive, and had the interpositive enlarged onto either a 12x15 or 16x20 inch negative, from which a print of the corresponding size is made. Since the process is already unstable for the small prints, any increase in surface area renders the larger prints more prone to flaws and stains. The larger the print size, the more difficult it is to produce a flawless print.

Life of POP

Gelatin Silver Chloride Printing-Out Paper was introduced onto the market in 1884. In 1892 Kodak introduced its own version of POP under the name of Solio, and continued manufacturing a version of POP up until 1987 when it withdrew its last POP Kodak Studio Proof from the market. In 1988 Guilleminot in France re-introduced a POP but subsequently withdrew the paper when the company went into receivership in 1994. In 1996, Kentmere, Ltd. introduced Centennial POP which has remained on the market with some ups and downs until the present.

Given that the first workable silver chloride paper was made by Fox Talbot in 1835 (49 years prior to the introduction of POP) and has been on the market for 121 years (since 1884), it is remarkable that POP, which lost its key market advantage a mere 21 years after its initial introduction, has nevertheless continued to be manufactured in one form or another for almost a century and a quarter after its displacement. Why has POP endured so long when countless other papers have long since disappeared?

POP is the only paper on the market on which pre-developing-out negatives could be printed--for instance, all the negatives originally printed on salt paper and albumen and early POP, as well as glass plates. So it was kept alive by its historical usefulness. Additionally, due to its capacity to produce a visible print instantaneously on exposure to light, it was utilized as a proofing paper, especially by portraitists who wanted to deliver a proof, but not have it kept as the finished print. This is why Kodak's last line of POP was called Studio Proof. And lastly, in its present use as a photographic arts paper, it is capable of producing prints richer and more luminous than any other paper on the market today.

Reference Dates

1835          Fox Talbot makes first successful salt prints on paper

1840-1855  Salt Print period (matte prints)

1855-1890  Albumen Print period (glossy prints)

1884          Printing-out paper first introduced on the
                 photographic market in Munich

1892          Kodak introduces Solio POP

1884-1905  POP period

1905          Developing-out prints

1987          Kodak withdraws its last POP Studio Proof Paper
                 from the market.

1988          Guilleminot in France re-introduced one of its vintage
                 formulas for POP

1994          Guilleminot withdraws POP from market

1996          Kentmere, Ltd. introduces Centennial POP

D. R. COWLES, Montréal, 1/21/05