ABSTRACT
Many of the techniques for image manipulation used routinely in contemporary photographic practices can be applied in gumoil either to the enlarged positive transparency or to the enlarged internegative. The gelatin silver photographic printmaking, gumoil prints can be manipulated in three basic ways. First, alterations can be made as the picture emerges in the printing process, during the coloring. Second, alterations can be made after the picture has been printed or partially printed—that is, by overprinting a first image, using a combination of more than one method. And third, alterations can be made by intervening much earlier at one of the film stages, either by manipulating the original negative or by manipulating the enlarged positive transparency in the special case of gumoil. Vandyke printmaking is a variation on the somewhat more elaborate kallitype process. The chemistries producing Vandyke images and cyanotype images are highly valued photographic printing methods in their own right.
