Woodburytype

A Woodburytype is both a printing process and the print that it produces. In technical terms, the process is a photomechanical rather than a photographic one, because sensitivity to light plays no role in the actual printing. The process produces very high quality continuous tone images in monochrome, with surfaces that show a slight relief effect. Essentially, a Woodburytype is a molded copy of an original photographic carbon print.

The process was introduced by Walter B. Woodbury and was in use during the final third of the 19th century, most commonly for illustrating fine books with photographic portraits. It was ultimately displaced by halftone processes that produced prints of lower quality but were much cheaper.

A dichromate-sensitized sheet of gelatin is exposed to UV-rich light through a photographic negative, causing each area of the gelatin to harden to a depth proportional to the amount of exposure. It is then soaked in warm water to dissolve the unhardened portion of the gelatin. The resulting relief image is pressed into a thick sheet of lead under about 5000 pounds per square inch of pressure. This creates an intaglio metal printing plate, which is used as a mold. It is filled with liquid pigmented gelatin and a sheet of paper is then pressed down onto it, squeezing out the excess gelatin and attaching the remainder to the paper. After the gelatin has set sufficiently, the print is stripped from the mold, trimmed, and usually mounted onto a larger sheet or card.

The Woodburytype process was invented by Walter B. Woodbury and patented in 1864. It was the first successful photomechanical process fully able to reproduce the delicate halftones of photographs. It produced true middle values and did not make use of a screen or other image deconstruction method. 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.

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