From: Darryl Baird (dbaird@flint.umich.edu)
Date: 04/11/00-06:50:10 AM Z
three more replies, all confirming your suspicions, Suzzanne
1.
I think the gentleman was confused. The plates have to be developed
and fixed before the emulsion hardens. Collodian is basically
nitrocelluose
i.e. a plastic and impervious to water when hardened.
I suppose it would eventually deteriorate like old time movie film
but certainly not for a while.
The plate was coated with the collodian mix, dunked in silver nitrate
solution, put in the camera while wet, exposed, developed and fixed
right
away. Hence the term "wet plate process."
The prints were made later after the plate was dry.
The process is described in "Keepers of Light."
Bob Schramm
-----------------------
2.
Unlike the old movie film, the wet plate process doesn't use an emulsion
but
a collodion film on a glass substrate. The final image was usually
varnished to protect it, and there are numerous examples over 140 years
old
that have survived well. If the photographer wished to travel light, he
could, after development and water rinse, fix the plates back at his
home
base by keeping the plates moist until then with no adverse effects.
Mike Steinle
---------------------------
3.
You are quite right to question the tour leader's statement/claim.
Collodion has to be kept in a wet for the duration of the exposure and
is
best developed whilst in the field. Some operators, including
John'China'
Thomson would immerse his plates in a bath of Potassium Bromide, dry and
store them away from the light and then fix them in Potassium Cyanide
when
they had returned to base. Printing in the field, in situ, was rarely if
ever done. To produce decent prints, properly processed, toned, fixed
and
washed requires good clean conditions. Your tour guide is clearly giving
an
inaccurate and misleading account.
Collodion negatives do not deteriorate on drying.
They cannot be printed wet; this is an absurd suggestion.
Collodion, if varnished is inherently more stable than gelatine dry
plate. If you wish to read a short succinct description read Richard
Ovenden's book on John Thomson (published by HMSO, UK) which contains a
description of the process by yours truly or, better still, read Scully
and
Osterman's Collodion Journal.
Michael Gray, Curator, National Trust, Fox Talbot Museum
-----------------------------
-- Darryl Baird
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