From: roger kockaerts (permadocument@yahoo.com)
Date: 08/17/02-09:52:41 AM Z
Hello Sandy,
The idea of testing and comparing diferent kallitype printing styles is a good idea. In photoconservation we do a lot of accelerated aging tests on photographic emulsions. In order to be comparable you have to keep te different factors (light, temperature, humidity) as stable as possible during your test. For example high temperature ( >25°C), high humidity (>60% RH) and light at > 300 lux are adverse conditions for any photographic emulsion.If you can maintain your factors stable during a year I guess you can get some evident conclusions. Otherwise the scientific value of your test will be about nihil and all you would be able to confirm is that a gold toned or platinum toned kallitype is more stable than a straight print. But..., we allready know this.
Gasparino did, in fact, try to establish that kallitype is/was as good as platinotype and that many so called historic platinotypes are in fact kallitypes. But he did not try to chemically analyse historic prints in order to prove his assumptions.
Anyway, good luck with your test!
Greetings from Brussels,
Roger
photographic conservator-restorer
Sandy King <sanking@clemson.edu> a écrit : Judy Seigel wrote:
>ome further thoughts, however. Have you got that blue paper, or
>whatever they call it, to put in with? When calculating change or no
>change would be good to have a benchmark. I have a pack of it but it's
>old... think I got it from.... Light Impressions? Or other conservation
>source.
What is blue paper? As for bench marks I plan to also include in the
tests a real platinum and a real carbon print, plus I will also note
the reading for paper base, that is, the areas that receive no
emulsion and no exposure.
>
>I also wonder what paper the tests are on. Would results be different on
>other, equally revered paper?
The tests are on Fabriano Artistico, which has proven to be a very
good and consistent paper for me. I considered running the tests on
other papers as well, and also introducing some other variables, but
that thinking was leading me down the road to to a a very large and
unwieldy situation.
>
>Finally, are you in touch with a photo conservator? What are considered
>to be the factors that deteriorate photos? While survival of the Ride In
>Sandy's Car would/should be reassurance enough for any of us, I figure
>that carbon monoxide and light aren't the only factors: Humidity is not
>good either, right?
I have not consulted with any photo conservators but have read
Wilhem's work and consider myself fairly conversant on the issues.
There are clearly some concerns that this test will not address but I
think it will address the most important ones that I see as specific
to kallitype, i.e., the impact of residual iron on light stability,
and the degree to which toning provides greater archival qualities to
a kallitype.
>
>Why the choice of the car? Because it's heat and light? What about your
>oven --? I have a vague memory of low oven for X time being used, I'm
>sure for much less than a year, so we wouldn't have to stay on tenter
>hooks so long...:-)
I chose the car because the prints will be subject to a lot of light
all year round, and they will also be subject to a lot of humidity
and heat. For example, my car is left closed with the windows up
about 90% of the time, and temperatures often rise up to well over
120F. As for using the oven, wife won't have any of that.
Sandy
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