Re: RC paper longevity

From: roger kockaerts <permadocument@yahoo.com>
Subject: Fwd: Re: RC paper longevity
Date: Sun, 07 Nov 2004 10:38:44 +0100 (CET)

> I would like to add that storage conditions are quite important for
  RC paper conservation.

Storage condition is very important for both baryta and resin coated
papers. Baryta prints may better sustain under slightly harsher
storage condition than RC, but the difference is not large.

Standards give numbers like life expectancy of several hundred years
for well processed silver gelatin material, but the condition is that
the materials be stored at certain temperature and humidity range, as
well as in absence of oxidative agents such as those given off from
paints, degrading cardboard, etc. This ideal storage condition is in
practice very difficult to achive at anywhere but large museums.

Given less than ideal storage conditions, what is also important is
sufficient level of protective toning. Prints that are toned in
sulfiding toners are significantly more permanent than those that are
not toned. Kodak Rapid Selenium Toners used to be recommended, but
from publications in 1990's, I see more reports suggesting that
sulfiding toning is superior and preferred.

In other words, untoned baryta prints are much more susceptible to
image degradation than well toned RC prints. No matter what material
you use, I would not consider your prints last long unless they are
well toned in sulfiding toners or gold toner. On the other hand, most
of the problems seen with RC prints in last two decades are related to
oxidative attacks. Manufacturers say they made improvements in RC
papers to prevent these problems. Sulfiding toning is another stage of
powerful protection, probably it's safe to say more poweful protection
than what manufacturers did, against those problems.

Finally, I would not store any films and prints, fiber or resin
coated, toned or untoned, in conditions where humidity level can get
high. Among variables in storage conditions, if you have to pick one
to pay close attention, humidity is number one. (Also avoid storage
containers that are not archival, but I assume everyone does that.)

--
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)