Platinotype, also known as platinum printing or the platinum process, is a historic photographic contact printing process that produces images formed in platinum metal rather than the silver of conventional photographic processes, resulting in prints of extraordinary tonal beauty, exceptional archival permanence, and a distinctive matte, velvety surface quality that has made the process highly prized among fine art photographers and collectors from its introduction in the 1870s to the present day. The process was patented by the English photographer William Willis in 1873 and commercialised through his Platinotype Company from 1879 onwards, becoming widely available to photographers for the first time and finding enthusiastic adoption particularly among the pictorialist movement of the late nineteenth and early twentieth centuries.
The platinotype process is based on the light sensitivity of iron salts in combination with platinum compounds, exploiting a photochemical reaction quite different from the silver halide chemistry that underpins conventional photographic processes. To prepare a platinotype print, a sheet of fine quality paper is coated by hand with a sensitising solution containing ferric oxalate and a platinum salt - typically potassium tetrachloroplatinate - dissolved in water, and allowed to dry in subdued light. The coated paper is then placed in direct contact with a large format negative - typically a glass plate or large format film negative of the same dimensions as the desired print, as the contact printing process produces no enlargement - and exposed to ultraviolet light from the sun or an artificial UV source.
During exposure, the ferric iron salts in the sensitised coating are reduced by the ultraviolet light passing through the transparent areas of the negative to ferrous iron compounds, in proportion to the amount of light received at each point in the image. The degree of ferrous iron reduction corresponds directly to the tonal values of the negative - greatest reduction occurring under the most transparent highlight areas of the negative and least under the densest shadow areas. After exposure, the print is developed in a solution of potassium oxalate, which causes the ferrous iron compounds to reduce the platinum salt to metallic platinum at each point in the image, producing a deposit of finely divided platinum metal that forms the visible image. The residual iron salts are then cleared from the paper in a series of dilute acid baths, leaving a pure metallic platinum image embedded within the fibres of the paper support.
The resulting platinum print possesses several qualities that distinguish it fundamentally from silver based photographic prints. The tonal scale of a platinum print is exceptionally long and smooth, capable of rendering the full range from the deepest shadows to the most delicate highlight gradations with a continuity and subtlety that surpasses most silver processes. The surface of a platinum print is inherently matte, as the platinum image is embedded within the paper fibres rather than lying on a surface coating as in conventional silver gelatin prints, giving it a soft, tactile quality that integrates harmoniously with the texture of the paper support and lends the image a quality reminiscent of fine art printing techniques such as lithography and gravure. The image colour of platinum prints ranges from a warm brownish black through neutral black to a cool blue-black depending on the paper, chemistry, and development conditions used, with subtle variations in toning available through the incorporation of palladium salts - producing the closely related palladium or platinum-palladium process - or the addition of other chemical modifiers.
The most remarkable property of the platinum print from an archival perspective is its extraordinary resistance to deterioration and fading over time. Platinum metal is among the most chemically inert and stable elements known, resistant to oxidation, acidic and alkaline attack, and the atmospheric pollutants that cause silver photographs to tarnish, yellow, and fade over decades. Properly made and stored platinum prints have a theoretical permanence measured in hundreds or thousands of years, and surviving platinum prints from the 1880s and 1890s remain in pristine condition today, with no evidence of the fading, yellowing, or silver mirroring that afflicts silver gelatin prints of the same era kept under similar conditions.
The platinotype process was particularly embraced by the pictorialist movement of the late nineteenth and early twentieth centuries, whose practitioners valued its painterly tonal qualities, matte surface, and fine art aesthetic as a means of elevating photography to the status of fine art by distancing it from the mechanical precision and glossy surfaces associated with commercial silver photography. Photographers including Frederick Evans, Gertrude Käsebier, Edward Steichen, and Clarence White produced some of their most celebrated work in platinum, and the process became strongly associated with the pictorialist ideal of photography as a medium of personal artistic expression rather than mechanical documentation.
The commercial availability of platinotype materials declined sharply during the First World War, when platinum was requisitioned as a strategic industrial material and its price rose to levels that made the photographic use of platinum compounds prohibitively expensive for most photographers. The process never regained its pre-war commercial prominence, but has survived and experienced a sustained revival among alternative process photographers, fine art printmakers, and collectors who value its unique aesthetic and archival qualities. Today platinotype and the closely related palladium process are practised by a dedicated community of photographers worldwide who hand coat their own papers and process their prints using carefully sourced chemical materials, producing work of a quality and permanence that remains unmatched by any other photographic printing process.