Unblinking Eye
                                                 Uranium

 

Uranium

by Robert W. Schramm

Figure 1:  Nude #8

         The element uranium is generally thought of today in connection with nuclear reactors or atomic bombs, but in the 19th century and the early part of the 20th century it played a significant role in photography.

         Most often it was used as a toner, producing red-brown tones on silver prints and blue, green and red tones on platinum prints. In 1858, J. C. Burnett and Niépce de Saint Victor patented a uranium printing process. A uranium print, which uses uranium metal instead of silver to form the image, is sometimes called a uranotype. Commercially made uranium printing paper was made until 1899.

Uranium Toner

         Most toners either bleach or intensify a print. Silver prints to be toned in uranium must be printed a little lighter than usual since the toner will add density and contrast to the image. Also, as a general rule, prints to be toned should be completely fixed and thoroughly washed until all the hypo is removed. Toning works best if a non-hardening fixer is used. Toning is done with the lights on. The process is slow enough so that it can be done by inspection. A wet print is slid into the toning bath and left there until the degree of toning desired is

Figure #2: Rooftops of Paris

reached. It is then removed and washed again. The uranium nitrate in the toner is quite toxic so under no circumstances should you put your fingers in the toning bath. It can be absorbed through your skin so you must wear gloves. Latex gloves won’t do. Get some Vinyl gloves and use print tongs. Watch out for splashes as well. Wear safety glasses and a long sleeve shirt.

 

         Of course uranium is radioactive but unless you plan on drinking the toner or taking a bath in it it there is nothing to worry about since the amount of uranium in the toner is very small. A sensitive Geiger-Muller counter registers no activity on the surface of a uranium print or on the outside of a bottle of toner. It would require an extremely sensitive scintillation counter to pick up any radiation. Yes, some uranium goes down the drain in the wash water, but again it is a minuscule amount. The amount of radiation is so small that it is much less than natural radiation due to radon gas or that of radioactive isotopes that occur in clay, shale and brick.

Figures 1 & 2 are uranium-toned  silver prints using two different formulas for the toner.

Uranium Prints (Uranotypes)

Figure 4:  Petit Pont, Paris

         The uranium print, as you can see in figures 3 & 4, consists of shades of red-brown tones. The process is such that a fairly high contrast and dense negative must be used. Also the print paper is very slow so that only contact printing can be used.; therefore, a negative the size of the final print is needed. An ultra-violet light source must be used. Sunlight works well. For best results the negative should be one that, if you were printing in silver, would be printed at 0 or 1 contrast grade. If you don’t have a contact print frame, you can make one out of two sheets of plate glass and some duct tape. 

         The first step in the process is making your own print paper. Mix the sensitizer (again wear protection) and coat some sheets of good watercolor paper with the sensitizer using a sponge brush or a Hake brush ( Do not use a brush with a metal ferrule). You can coat under dim incandescent light (15-40 watt bulb). Hang the paper up to dry in the dark. Let it dry naturally, do not use a  hair dryer! When the paper is dry, it is ready to print. It does not store well, so you

Figure 4:  M. Gargoyle, Notre Dame

should use it right away. After exposure, the print is developed in a developer of choice (usually potassium ferricyanide) and washed.

         Those of you who are alternative process printers should have no difficulty with this process. However, if you are  new to alternative process printing, I would suggest you try something easier and less toxic first, like cyanotype, until you get the hang of dealing with the chemistry, making negatives and coating paper.

         I did a little survey a few months ago to see if there were any uranium printers besides myself and did not find any, so, should you decide to try this process, you will become a member of a very exclusive club. I will attempt to answer any questions you might have about uranium toners and uranium prints. My email address is:  schrammrus@hotmail.com.   Also, you can see more examples of my work at www.schrammstudio.com.

         There are several formulas for uranium toner and for making uranium prints. Here are two that I have used and that work well. Mix each chemical into the water in the order in which they are listed.
 

Uranium Toner

Distilled Water

700 cc

Uranium Nitrate

8 g

Oxalic acid

4 g

Potassium Ferricyanide

4 g

Distilled Water to Make

1 liter

Uranotype Solution

Sensitizer

Uranium Nitrate

4 g

Distilled Water

16 cc

Developer

Potassium Ferricyanide

10 g

Distilled Water

300 cc

All of these solutions are reusable and keep well, but store them in well-sealed amber glass bottles.


Article and images copyright 2002 by Robert W. Schramm--all rights reserved.
No part of this article may be reproduced in any form without the express permission of the author.
 

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