The Wothlytype was an alternative photographic printing process, the eponymous 1864 invention of the German Jacob Wothly, in which a mixture of uranium ammonio-nitrate (uranyl nitrate) and silver nitrate in collodion formed a light-sensitive layer. It was a short-lived positive printing process proposed to remedy the recognised impermanence of albumen paper, and compared to which, it was considerably more light-sensitive. Wothlytype printing-out-paper was superseded by collodio-chloride papers before the end of the 1860s.
Characteristics
The Wothlytype enabled positive prints to be made directly on paper. The photographic emulsion consisted of a special uranium collodion that replaced the iodide, the chlorine or silver bromide. After exposure, the image was directly visible and was fixed immediately. Toning could be achieved in varying tones from deep blue-black to purple black. Sensitivity, efficiency and economy (reducing to degree the use of expensive silver) were advantages over competing processes. In addition, the collodion layer could also be transferred to ivory, wood, glass, porcelain and similar materials.
Procedure First, the uranium collodion was applied to the paper, which was done with a brush, sponge or in a sensitizing bath, depending on the type of paper. After exposure, the images were immersed in an acidic bath for cleaning. The prints were washed to remove the acid, then immersed in a toning bath and then in a fixer. These two operations could also be combined. Finally, the images were washed a second time.
The British patent made public these details in the specification;To one pound of plain collodion add from two to three ounces of nitrate of uranium and from 20 to 60 grains of nitrate of silver. The paper is prepared for printing by simply pouring the above sensitized collodion upon its surface, and hanging the sheets to dry in the dark. The printing is accomplished by exposing the paper to light under the negative in the usual manner, and for about the usual time required for silvered paper; print until the desired depth is reached. It is not necessary, as in the ordinary process, to print the positive to a greater intensity of color than the fixed picture is intended to have. After printing immerse the picture in a bath of acetic acid for about ten minutes, or until that portion of the salts not acted upon by the light has been dissolved. The picture is now fixed and finished by thorough washing or rubbing with a sponge or brush, or by rinsing in pure water; then dry. Changes in the tone of the picture to suit the taste may be made before drying, by using a bath of chloride of gold, or of hyposulphite of soda.Richard Kingham published further instructions for the amateur in 1865.
History Wothly was a portrait photographer in business before 1853 and working in ambrotypes, whose studio was in Theaterplatz in Aachen. He went on in 1860 to make improvements to Woodward's solar camera. Even before Wothly, numerous photographers had tried to use uranium salts in photography without lasting success. Wothly in 1864 introduced his new uranium platinum collodion process for positive paper images, in which he used platinum and palladium compounds to reduce the uranium salt. The Wothlytype was patented in Germany, America (15 August 1865), Belgium (15 February 1865/No. 17147), England, France (24 September 1864), Portugal and Spain. For France and Belgium, the Société française de Wothlytypie, founded specifically for this purpose by Emmanuel Mangel du Mesnil, took over licensing and distribution.
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