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The term Woodburytype refers to both a photomechanical process and the print produced by this process. The process produces continuous tone images in slight relief. A chromated gelatin film is exposed under a photographic negative, which hardens in proportion to the amount of light. Then it is developed in hot water to remove all the unexposed gelatin and dried. This relief is pressed into a sheet of lead in a press with 5000 psi. This is an intaglio plate. It is used as a mold and is filled with pigmented gelatin. The gelatin layer is then pressed onto a paper support. ==History== The Woodburytype was developed by Walter B. Woodbury in 1864, first used in a publication in 1866 and widely used for fine book illustration from about 1870 to 1900.〔Ovenden, 216; Rosenblum, 198; Bloom, 30. Auer and Auer give the date of its invention as 1866.〕 It was the only commercially successful method for producing illustration material capable of replicating the subtleties and details of a photograph. It is the only mechanical printing method ever invented which produces true middle values and does not make use of a screen or other image deconstruction method. The Woodburytype process was invented by Walter Bentley Woodbury (British, 1834–1885) / Joseph Wilson Swan (British, 1828–1914). Patented 1864, working details published 1865. The Woodburytype process was one of the first successful photomechanical processes fully able to reproduce the delicate halftones of photographs. It was often considered the most perfect, most beautiful photomechanical process and inspired a number of books, magazines, and special edition printings between 1864 and 1910. When attempts were made to adopt Woodburytype to rotary printing, the process could not compete with the quickly developing collotype and halftone photomechanical processes that almost completely replaced Woodburytype by the end of the nineteenth century. Like many practical inventions, the Woodburytype process is based on a number of previous discoveries and processes. The process utilizes the photosensitivity of dichromate-containing organic colloids, discovered by Mungo Ponton (1839). The photochemical formation of the gelatin relief dates back to the first carbon printing patent of Alphonse-Louis Poitevin (1855). The idea of washing unhardened gelatin from the lower part of an exposed gelatin layer comes both from the early experiments of Adolphe Fargier (1861) and from the development of Joseph Wilson Swan’s fully practical carbon-transfer process (1864). The idea of creating a metal mold out of gelatin relief using both lead plate and electrotyping has its roots in nature printing, which was fully developed and patented by Alois Auer in Austria (1852). It is also not unusual that the priority of “photorelief printing” was highly contested by both Walter Bentley Woodbury and Joseph Wilson Swan, who developed and patented two almost identical photomechanical processes (1864–65). Regardless of the fact that many historical findings speak to Swan’s priority of original ideas of the photorelief process introduced under the name photo-mezzotint, it was Woodbury who advanced his research ideas into a fully workable and practical method of photomechanical printing of continuous-tone photographs. Woodbury’s patents in England, France, Belgium, and the United States, as well as production of several Woodburytype process printing establishments in England, France, and the US, were responsible for the printing of hundreds of thousands of Woodburytype photographs that provided book and magazine illustrations, short-run advertisement material, and promotional material. A number of Woodburytype images were also printed for sale as individual images or as cartes-de-visite (CDV) or cabinet cards (CC). Woodbury himself and a number of other researchers continued to improve various practical aspects of the Woodburytype process. Several important variants of the Woodburytype process were also developed and used on a very limited scale. The Woodburytype process was a unique photomechanical process as it was the only practical fully continuous-tone photomechanical process ever invented. Woodburytype prints made using only carbon black or other stable inorganic pigments as imaging material are superbly stable from light fading. The stability of the gelatin binder might be compromised at higher temperatures and humidity due to biological deterioration. A number of Woodburytype prints were surface coated using collodion or other organic varnishes and coatings. The majority of Woodburytype prints are easy to identify because the process was clearly described in print in books and on many prints sold commercially. Those that are described as “permanent prints” or not described at all, however, can be difficult to identify correctly even when using highly sophisticated analytical methods. English: Woodburytype, photorelief printing, Woodbury’s process, relievo printing French: photoglyptie German: Woodburydruck 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「woodburytype」の詳細全文を読む スポンサード リンク
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