Woodburytype
A BRIEF TECHNICAL EXPLAINATION OF THE WOODBURYTYPE PROCESS
In the 1880's, Walter Woodbury invented and patented a process he named "Woodburytype". It was the first process to allow commercial reproduction of photographic images without any loss of quality. Even by today's standards, surviving examples of Woodburytype prints exhibit a striking rendition of tonal range and clarity. His technique for printing photographs utilized a relief surface created by chemical action.
The steps used to create a Woodburytype are:
1. Create a photograph on film for contact printing.
2. Prepare a thick slab of sensitized gelatin and expose it through the film.
3. Wash the gelatin slab under hot water to remove areas that were not hardened by exposure to light. This produces a surface relief that contains accurate continuous-tone information.
4. Dry the gelatin slab, harden with alum, then place on a hydralic press between a sheet of steel and a sheet of lead. The lead faces the relief side.
5. Under great pressure, the details of the surface of the gelatin are transferred to the lead sheet. This lead sheet will be used to make prints.
6. The lead sheet is lightly oiled, a warm mixture of pigmented gelatin is poured into it, and a sheet of paper is laid on top with light pressure. When the gelatin has sufficiently cooled, the paper is removed, taking the gelatin with it.
When the Woodburytype image is first released from the mold, it contains all of the original surface relief present in the gelatin slab. Upon cooling, and evaporation of all water, the gelatin layer becomes almost flat. When carefully scrutinized, an original Woodburytype print will be seen to still exhibit a minute bit of relief and small differences in gloss resulting from the varying thickness of material deposited.
Because excess gelatin was squeezed out of the edges of the mold during printing, Woodburytypes were always trimmed to the image area.
Contemporary artists wishing to undertake work with the Woodburytype process can substitute epoxy or plaster for the lead sheet, thereby eliminating the need for the large and expensive hydraulic press.
For more information click on the "Link to Info" button at left. It will take you to a long illustrated article on this process.
|
