Today, almost no one prints on Azo, the last of the silver chloride contact printing papers, and the finest paper on which to print black and white negatives. Most of those using large-format negatives and making contact prints are printing on enlarging paper, or, dissatisfied with their silver prints, are making platinum prints. When asked if they have had any experience with Azo, most photographers answer that they can’t get good prints with it or that it is not being made any more. Surprise—although most camera stores do not stock it, Azo is still being manufactured. Azo is the longest continuously manufactured photographic paper ever made. It was first introduced by Photo Materials Company in Rochester back in 1898. In July of that year Kodak bought out Photo Materials, and has been producing Azo ever since. This article will describe this unique paper and explain how you can make beautiful prints with it.


In 1966, when I first began to make photographs using a 35mm camera, the camera store I dealt with told me that if I was going to make contact sheets as well as enlargements I would need contact printing paper. They sold me a 100-sheet box of Azo.

The quality of those first contact sheets was far better than my enlargements—the blacks were richer and there was a glow to those small prints that I just couldn’t get in the enlargements. At that time, and for many years after, I assumed the inferior quality of the enlargements was due to the enlarging process. It was not until later—after I had spent eight years making contact prints on chloro-bromide or bromide enlarging papers and still could not achieve the quality of those Azo contact sheets—that I came to realize that the problem was due to the enlarging paper itself.

As I learned more about fine print quality, I experimented with many papers: Kodak papers—Kodabromide, Medalist, and Polycontrast; Agfa papers—Brovira and Portriga Rapid; and DuPont papers—Velour Black and Varigam. I settled on Velour Black. After only nine months of working in 35mm, I began using an 8x10-inch view camera and began making only contact prints, but I continued to use Velour Black. From time to time I would hear murmurings about Azo, and about once a year would try to make prints on it, but I was unable to do so to my satisfaction. In 1975 when I showed my photographs to Dody Thompson, once Edward Weston’s assistant, and she confirmed that something in my prints was missing, I determined to learn to print on Azo. And now it is the only printing paper I have used for over twenty years.

About ten years ago I reprinted my earlier 8x10-inch negatives on Azo—negatives that originally had been printed on enlarging paper. Even though I had been printing with Azo for ten years, I was still surprised by the difference in the quality of these reprints. They were remarkably and vastly improved. In some cases, the new Azo prints looked almost as if they were from different negatives. And the printing process was far easier and quicker—less dodging and burning and still more detail in the highlights and in the shadows.

The main thing that distinguishes Azo from enlarging papers is its incredibly long tonal scale. Even without dodging or burning, the dark tones and high values do not block up, but hold full detail. It is as if the curve of the paper is a long straight line, with neither toe nor shoulder. One photographer, an excellent platinum printer, who tried printing on Azo, told me that his prints from the same negatives that he had previously printed on platinum had a longer tonal scale when printed on Azo.

Besides having an extremely long scale, Azo has particularly rich blacks. And recent tests I have conducted show that when compared to enlarging papers it has more contrast in the midtones, giving the prints a glowing richness and greater depth.


Exposing: Silver chloride papers are much slower than enlarging papers. Exposure through an enlarger is impractical; the times would be prohibitively long. I recommend using an R–40 300-watt light bulb, one with the silvered part on the neck of the bulb. The average exposure should be between 10 and 20 seconds, but fine prints can be made with exposures as short as 3 seconds and as long as 3 minutes. Azo can handle almost any negative.

To make contact prints, any contact printing frame will work fine, but use of a vacuum frame is preferable. It is much quicker. (So that the noise of the vacuum pump is not a distraction, I keep it outside of the darkroom, two rooms away, running a long hose through the walls.)

Dodging and burning take place between the light and the negative, not between the negative and the paper as with enlarging. To cover a large area a large card is used. You can’t raise a small card closer and closer to the light bulb as you can when an enlarger provides the light source. Keep in mind that because of Azo’s long tonal scale far less dodging and burning are needed than with enlarging papers. As stated earlier, dark areas of Azo prints will not block up; they will maintain openness and detail. At the other end of the scale, the highlights will not wash out easily; they hold tone and detail into the lightest areas. This is one of the reasons that Azo is extremely easy to use.

Development Time: Here is another area where working with Azo is significantly different (and easier!) than working with enlarging papers. Where enlarging papers usually take between two and three minutes to develop, the ideal developing time for Azo is only one minute. Even less time—down to 45 seconds—can be okay. Rarely is more developing time necessary or desirable. The longer the developing time, the cooler Azo becomes and the more "on the surface" of the paper the image seems to be. The shorter the developing time, the warmer Azo is and the more depth the print seems to have—the more in the paper the image appears to be. Scientifically, this may be the exact opposite of what is actually happening; usually, the longer the development time, the more in the depths of the emulsion the image is physically, but here one’s visual perceptions must override scientific explanation.

Developer: I have used Amidol since 1970 when I was still contact printing on enlarging paper. While I believe most print developers would work with Azo, I have not done extensive experimentation and testing in this area. While my decision to use Amidol may have been originally determined by the, "If it was good enough for Edward Weston, it is good enough for me" approach, use of this print developer for over twenty-five years has convinced me that it has significant advantages over other more commonly used developers—the most important being, of course, that with continual use it will stain your fingernails black, marking one as a "real photographer." Actually, agitation by rocking the tray, rather than by putting your hand in and swishing the paper around will keep your nails from turning entirely black. Note: Never use tongs with Azo. It is a fragile single weight paper and is easily creased and damaged.

Amidol is the most active developer known—it has the greatest reduction potential of any developer. However, in this formula it is a soft-working developer. The major difference between this formula and others is the extremely small amount of Potassium Bromide used. That’s the secret. The Citric Acid acts as a buffer and extends the life of the developer. Contrary to the rumor that Amidol lasts for just 15–20 sheets of paper, a tray of developer can be used for an entire printing session with no reduction of its developing strength.




Note that in tripling the volume of water, not all of the ingredients are tripled; the Amidol is only increased two-and-a-half times and the Potassium Bromide is increased four times. For quantities larger than three liters or in between one and three liters, simply extrapolate.

Amidol and the use of a water bath: Sometimes it happens that a negative prints too soft on a lower grade, and too contrasty on the next higher grade. When using a water bath a compensating action occurs and it is possible to get to any point in between those grades. The print is first immersed in the developer with full agitation. Then at the appropriate moment, the print is taken out of the developer and put in a tray of water—now with no agitation. What happens is that the darker areas of the print will stop developing, having used up all of the developer that was in contact with the paper at those locations. In the highlights, development continues. The result is a print with both fully detailed highlights and open shadow areas. Relative to the highlights and shadows, the mid-tones are unaffected. By using one grade of paper higher than necessary and the proper use of the water bath it is possible to get the lighter and darker tones the way they would be on the softer grade, yet having the midtone separations of the higher grade. This imparts a wonderful glow to prints that would otherwise be either a little too dull or a little too contrasty. Use of a water bath in this way is not unlike the use of a two-developer method (Dektol and Selectol-Soft, for example), but the use of a water bath is much easier.

Water bath development works particularly well with Amidol because it is the most powerful of the known developing agents. Because its reduction potential is so high it is not necessary to go back and forth from the developer to the water bath as it would be if another developer were used. To use Azo and Amidol in this way, go from the developer to the water and then directly to the stop bath. The time in the water bath counts as time toward the one-minute development. Of the one-minute development time, an average water bath use would be half the time, or 30 seconds. However, I once made a print with as little as 12 seconds in the developer and 48 seconds in the water. At the other extreme, I have also used as little as 10 seconds in the water bath. To know when to transfer the print to the water bath, look at the dark tones; when they start coming in to about 60%–80%, it is time to make the transfer. Too much time in the water bath (over 35 seconds or so) can sometimes result in streaking. The only solution I have found is to keep trying and hope the streaking does not occur.

The use of Amidol as a print developer complimented by the inherently long scale of Azo makes for an extraordinary combination. When they are used together, especially with a water bath, there is no need to resort to time-consuming, complicated, or esoteric processes and methods such as the use of ferricyanide and masking. And because far less dodging and burning are required than when using enlarging papers, printing becomes a real pleasure with Azo and Amidol.

Toning: My only experience with toning Azo is with Rapid Selenium Toner. Older Azo was noted for its ability to split-tone. Newer Azo does not split-tone as well, but will change color drastically if left in the toner too long. I recommend toning with highly diluted selenium toner—a dilution of 1:128 for only three minutes at 68°. This is mostly toning for archival permanence, but even with this modest amount of toning the slightly green cast of Azo will be eliminated.

Care of Handling: Except for Grade 2 in 11x14 size, Azo is available only in Single Weight. After years of using double-weight enlarging papers, I was quite concerned about using single-weight paper when I began printing on Azo. But I quickly found that with careful handling, damage was infrequent. I also learned that single-weight paper dry mounts better, the surface being closer to the mount board. To handle single weight paper there is only one bit of advice: Do not hold the paper with the thumb on one side pressing between two fingers on the other side. If you do, invariably a crescent shaped crease in the emulsion will result where your thumb falls between your two fingers. Hold the paper between the thumb and just one finger.

Availability of Azo:


Kodak stopped manufacturing all black and white papers in 2007, and then demolished the coating facilities so there was no hope for AZO's resurrection.  Although due to our own significant use of sliver chloride contact printing paper and demand in a small niche market we undertook a five year endeavor to recreate our own silver chloride paper with a photographic company in Europe to serve as a replacement. One day the whole story will be told.


© Michael A. Smith 1996