The details of the articles are as follows:
1. Yang-Hwan Lim ... et al. Relationship between Photographic
Characteristics and Molecular Weight Distribution of Dichromated Gelatin.
_Journal of Photographic Science_ vol. 41 (1993), 203-5.
Abstract: Gelatins possessing widely different molecular weight
distributions were prepared from a single gelatin by ultrasonic radiation.
Carbon tissues prepared using these gelatins were sensitized by dichromate
and their photographic characteristics were investigated. Sensitivity and
gamma values increased with increasing higher molecular weight components,
whereas the contrast transfer function and the acutance decreased with
them. The hardened structure of the gelatin layer was also dependent on
the molecular weight distribution. From the exposure dependence of the
molecular weight distribution of the washed-off gelatin it was elucidated
that the higher molecular weight components have the higher sensitivity.
2. Yang-Hwan Lim ... et al. Influence of Raw Material and Processes of
Gelatins upon Photographic Characteristics of Dichromated Gelatin.
J. Photog. Sci. vol. 41 (1993) 206-7.
Abstract: Carbon tissues prepared using different types of gelatin
differing in raw material [cattle hide, bone, and pigskin] and process
[lime or acid-processed] were sensitized by dichromate and their
photographic characteristics were investigated. Sensitivity and gamma
were dominantly determined by the higher molecular weight components
of the gelatin, sharpness and resolving power were predominantly
determined by viscosity; these properties were little affected by its
origin.
If memory serves, this confirms Luis Nadeau's statement in his book
on carbon printing that the origin of gelatin isn't that important.
These researchers (from Chiba University) are going on to test the
influence of pH; hopefully their research has some practical
implications.
Philip Jackson
pjackson@nla.gov.au