Hippolyte Bayard’s Direct Positive Process: History, Re-creation, and Characterization

Abstract

ABSTRACT Hippolyte Bayard is celebrated for his invention of the direct positive process of 1840. A direct positive process captures an image without a negative. In Bayard’s process, a sensitized sheet of paper is placed into the back of a camera, where the typical negative would have been placed. Direct positives are unique images, however they cannot be easily reproduced. One-hundred-and-eighty years have gone by since Bayard shared his first photographic process, yet, his system remains a mystery. The only extant notes are a series of published letters to the Académie des sciences and to editors in photographic journals. This study explores the scant surviving evidence by re-creating his recipes. Characterization was carried out with densitometry, colorimetry, X-ray fluorescence spectroscopy, X-ray diffraction and scanning electron microscopy.