Re: Does anyone know this person or the work (late)

Dear list and dear Ryuji

Sorry to reply so late to your question sent last august. but I was out
of my home for a long time. I teach BW silver based and alternative
processes at Louis Lumiere school and, with my friend Bertrand Lavedrine,
we were the supervisors of the study you quote in your message.
Each student of our school has to produce a personal project in the last
part of third year cursus (january-april).
The name of the student you are looking for is Emmanuel Bénard and the
tittle of the work was :
La sulfuration des papiers argentiques noir et blanc par les
polysulfures. Recherche sur l'optimisation de la stabilté par une
sulfuration minimale or translated : Sulfur toning of silver based BW
paper. Working on a method giving a better satbility with a low level of
sulphiding.

The starting idea of the project was asociated with a problem we meet,
from time to time, in the professional datkrooms and in many cases the
resulting conflicts between printer, photographer, paper maker, galery
owner and customer can be very difficult to solve ...
As you probably know, some modern baryta BW papers may be affected by
oxydation mechanism and an effective approach is to tone the prints with
a selenium bath. You must use a concentrated bath and let the paper in
the bath for a long time otherwise the silver/silver selenide conversion
ratio isn't high enough and you don't get a real archival treatment .
Following this way you have a color shifting of the paper tone towards
purple, not always wanted by the photographer.
The idea was to extrapolate the polysulfide toning bath elaborated by IPI
lab in Rochester and known under the name of SILVER LOCK. This treatment
was developed to extend the stability of microfilms and in this case, the
color shift wasn't a problem. Silver Lock is cheap, specialy when you
dilute it and much more safe and environmental friendly compared to
selenium. The core of the study was to work on diluted baths of Silver
Lock to quantify the level of protection associated with this alternative
approach. We used dilitions ranging from 1/1600 to 1/4000 on a batch of
baryta papers (Kodak Polymax, Ilford Warmtone, Ilford Galerie and Agfa
Classic).
To mesure the conversion ratio, we have selected a Farmer reducer in
place of dichromate bath (ISO paper) to avoid the staining problem of
chrom compounds in low level density areas. We were in contact with Doug
Nishimura at IPI during the study and we share the same ideas about
staining.

The oxydation attack was simulated with peroxyde test (A. Weyde biblio)
with a 2% concentration, HR 50 %, T 50° C, time 18 hours.
The treatment shows a good level of improvement under oxydation
conditions, specialy with the papers directly concerned with the problem
(labeled as chlorobromide or warm tone).
We made some complementary tests on conversion levels with X-Ray
difractometry and electronic microscope but the time associated with the
study was to short to be really effective concerning this question.

Emmanuel Benard is now far away from conservation field, I think he is
working for a local radio broadcast network in the south of France.
Scholarship is one thing, life another one ...
We have a school web site but the third year studies aren't yet avaliable
to downloading access; At this time, the only way is to ask for read it
at the school library, not so easy for foreigners. Works are in progress
to solve that problem and we hope to put them on-line shortly.

I am always interested in collecting informations from people involved
in baryta oxydation problems. You can contact me off-list if you consider
the thread off-topic but with the last informations given by european
paper and film makers I think silver based BW is slowly (quickly)
merging with alternative processes. Isn't it ?

Best regards from Paris and thanks again for informations shared on the
List.

Jean-Paul GANDOLFO
Louis Lumiere National School of Photography
Marne-la-Vallée
France
www.ens-louis-lumiere.fr

Ryuji Suzuki a *crit :

> From: nze christian <christian_nze@hotmail.com>
> Subject: RE: Does anyone know this person or the work?
> Date: Thu, 12 Aug 2004 08:32:11 +0200
>
> > All the student of the ENS Lumière should make a thesis so there is
> > a lot of good information in french
>
> I bet! But in the last message I meant I was interested in the work of
> E. Benard or of the same group (the supervisor, next student in the
> lab, et al) regarding the treatment of silver image with minimum
> polysulfide to optimize the stability, preferrably those published on
> peer reviewed journals. And I was also wondering if ENS has
> electronic thesis repository accessible from online... sort of like
> the one you gave reference to but in a more systematic one.
>
> For those interested in this topic, I read that Benard studied ways to
> protect silver b&w images with polysulfide and also examined methods
> of testing the adequacy of protection. The preferred method is
> ferricyanide bleach instead of dichromate bleach, which is in the ISO
> standard. This is the same as my personal experience, and I heard of
> Doug Nishimura's lab having some students to develop alternative to
> dichromate bleach several years ago, but I just did not know of any
> published data until now...
>
> --
> Ryuji Suzuki
> "You have to realize that junk is not the problem in and of itself.
> Junk is the symptom, not the problem."
> (Bob Dylan 1971; source: No Direction Home by Robert Shelton)
Received on Thu Sep 16 05:26:30 2004