> Thank you very much for posting those references. I have
> been experimenting with alternate sources of colloids for
> dichromate processes and have badly needed exactly this kind
> of information. It tells me what direction to look in
> selecting ingredients.
>
> Do you have other references of this kind?
>
> Dan Shapiro
Dan:
I don't think these articles will help you all that much with alternate
sources of colloids. From your previous postings I assume you're
interested in something like casein (from sour cream or cottage cheese)
as an alternative to gelatin. It's been awhile since I read them, but I
think there are some *practical* directions for casein in:
Laura Blacklow. New dimensions in photo imaging : a step-by-step manual.
Boston : Focal Press, c1989. ISBN 0240517555 (pbk.)
Peter Fredrick. Creative sunprinting : early photographic printing
processes rediscovered. London : Focal, 1980. (If there's nothing here,
there might be a recent article by him in the Photographic Journal).
A basic scientific survey on dichromated colloids is included in:
Jaromir Kosar. Light-sensitive systems; chemistry and application of
nonsilver halide photographic processes. New York, Wiley [1965] xv. 473
p. illus. 24 cm. (Wiley series on photographic science and technology
and the graphic arts)
Kosar mentions colloids like isinglass (fish glue) and agar. I'm not aware
of any more recent survey articles: there doesn't seem to be much research
being done in this area. Still, it might be worth trying an online search
of Imaging Abstracts (formerly Photographic Abstracts) or Chemical
Abstracts for further references.
I'm really only interested in gelatin and haven't done anything systematic
but have picked up a few references to dichromated gelatin for holography:
D. Meyerhofer. "Dichromated Gelatin" In: Holographic recording materials /
edited by H. M. Smith ; with contributions by R. A. Bartolini ... [et
al.]. Berlin ; New York : Springer-Verlag, 1977. xii, 252 p. : ill. ; 24
cm. (Topics in applied physics ; v. 20) ISBN 038708293X
S. Sjolinder. "Dichromated Gelatin and Light Sensitivity." Journal of
Imaging Science 30 (1986) 151-154.
Sven Sjolinder. "Dichromated Gelatin and the Mechanism of Hologram
Formation." Photographic Science and Engineering 25 (1981) 112-118.
Sven Sjolinder. "Swelling of Dichromated Gelatin Film." Photographic
Science and Engineering 28 (1984) 180-184
Despite its lower sensitivity, compared to silver, DCG is used for
holograms because of its high quality tone rendition. The mechanism of
image formation is quite different, however, and involves not so much
relief, with carbon particles or pigments dispersed in varying thicknesses
of colloid, but the brown print-out image (Mungo Ponton's 1839 process)
which affects refractive index modulation. Reading these articles
selectively some aspects of them can be useful e.g. Sjolinder confirms
the DCG absorbance peak at 372 nm. His article on swelling has some
relevance to woodburytype, but he's aiming at precisely the opposite
effect: minimising swelling, when I want to maximise it.
Chasing footnotes I discovered the first reference in the Lim et al.
articles is misprinted: it should be:
Masako Sasaki and Kenichi Honda. "Photosensitivity of the Gelatin
Films Containing Hexavalent Chromium Oxysalts" Graphic Arts Japan
15 (1973-74) 14-18.
This might be useful if you're interested in other chromium
compounds as an alternative to potassium or ammonium dichromate.
Hope this is useful, and you can actually do something with these
references. I've cross-posted it to the list in case others are
interested.
Philip Jackson
pjackson@nla.gov.au