Among the community of Canadian conservators and library specialists, it has
long been known that deteriorating paper is a major problem. The deterioration
of the paper base seriously threatens the survival of most of the published
materials and written records constituting the collections in Canada's
libraries and archives. The problem has gradually been recognized outside
conservator circles, so that now there is a considerable degree of public
concern. While a variety of efforts have attempted to protect current
collections from further deterioration, there has also been a greater focus on
prevention, including a move to increase the use of stable, alkaline-based
papers.
In January 1992, the government of Canada decided that all of its own
publications that could be expected to be retained would be printed on stable,
alkaline-based paper. This landmark decision was based on several factors,
including safeguarding the federal government's printed heritage, ensuring that
Canada's significant national records would survive, helping provide accurate
records of Canada's federal government, helping protect the rights of citizens,
and responding to the public's right to information while allowing for future
research. As a result of the decision, most Canadian manufacturers of fine
paper today can produce alkaline paper to meet the increased demand for paper
of much improved permanence.
The government's decision included a directive for the Canadian General
Standards Board (CGSB) to develop a national standard for paper stability
consistent with international standards.
The Lignin Debate
The first issue for the CGSB to resolve was the scientific debate about whether
lignin should be permitted or excluded in the paper manufacturing process. Most
existing permanent paper standards (ANSI, ISO, DIN in Germany) specify that
permanent paper should be alkaline and contain at least 2% calcium carbon-ate
to act as a buffer (or as an alkaline reserve) against acid hydrolysis of the
paper. Some of these standards (such as the ISO) recognize that paper with
lignin may have good strength retention, but the standards nonetheless allow no
more than 1% lignin because of the uncertainty about the impact of air
pollutants on lignin-containing papers. The restriction on lignin derived from
the observation that many papers made from mechanical pulps have poor
permanence. It was argued that this instability was caused by the presence of
lignin, which constitutes about 25% of the substance of most species of wood.
Not surprisingly, manufacturers of high-yield (lignin-containing) pulps
objected to the lignin-content restriction, while library and archival
communities advised caution about making changes to existing standards.
When the CGSB began looking at developing a new paper permanency standard,
it found evidence in recently published scientific work suggesting that
assumptions about the impact of lignin might be incorrect. Because this
scientific data was insufficient to draw firm conclusions, it was decided that
Canada should conduct research to determine whether lignin has a detrimental
effect on paper permanence. Hence, a number of Canadian users and manufacturers
joined forces in 1994 to launch a collaborative two-and-a-half year research
project.
Research Project
Under the auspices of the CGSB, the research plan was established and financial
support obtained from both government and industry. Project sponsors included
Industry Canada, Canadian Heritage, the National Archives, the National Library
of Canada, the Alberta government (Department of Economic Development and
Tourism), DuPont Canada, Fibreco Pulp, Louisiana Pacific, Millar Western Pulp,
Quesnel River Pulp, Tembec Inc., and Slave Lake Pulp.
The research was conducted in the laboratories of the Pulp and Paper
Research Institute of Canada (PAPRICAN, whose headquarters are in
Pointe-Claire, Quebec) and the Canadian Conservation Institute. The first
report on the work, prepared jointly by the two research teams, was presented
by CCI at the ARSAG (Association pour la Recherche Scientifique sur les Arts
Graphiques) conference in Paris in April 1997.
The project was divided into two components. First, 21 sets of handsheets
made from 6 types of pulp and 10 commercial papers were subjected to
accelerated aging. Papers of high and low stability were included for
comparison. The aging behaviour of this comprehensive set of papers was
determined using a wide variety of mechanical, chemical and optical tests. The
results clearly showed that it is acidity—not the presence or absence of
lignin—that is a dominant factor in the mechanical stability of paper.
Second, the researchers studied the impact of the gaseous pollutants sulphur
dioxide and nitrogen oxides on papers. This research showed that the presence
of lignin does not have a negative impact on permanency if the paper is
buffered with a sufficient amount of calcium carbonate.
Perhaps the key component of the CCI work was developing and using chemical
analysis techniques. Credit should go to Elzbieta Kaminska, contractor to CCI,
for her work in refining the method of measuring the degree of polymerization
(DP) of cellulose. The DP method has consistently been shown to be the most
sensitive analytical technique for detecting the early stages of paper
degradation. Thanks to Elzbieta, a major breakthrough was achieved in modifying
the technique for studying lignin-containing papers.
Future Plans
Since the research was completed, two major events have taken place. First, the
CGSB has revived a sub-committee of its committee on Printing and Writing
Papers (Permanence of Paper) to write the first Canadian permanency standard
for paper. Cliff McCawley, Director of Conservation and Scientific Services,
has been appointed chairman of this group. Second, CCI has initiated another
paper permanency project. Over a year ago, CCI was successful in its bid to
conduct work for the Institute for Standards Research of the American Society
for the Testing of Materials (ASTM) in Philadelphia on the effects of aging on
printing and writing papers. The project began on May 15, 1997, with the award
of the first part of a two-year grant of US $130,000.
The aim of this latter project differs from the Canadian study. It is being
conducted to develop better test methods for paper and thus to enable future
standards to be based on the performance rather than the composition of papers.
CCI joins a team composed of groups from the Library of Congress (Washington,
D.C.), the Image Permanence Institute (Rochester, New York), and the Forest
Products Research Laboratory (Madison, Wisconsin). A technical meeting of the
group was held at CCI on May 7th and 8th. The meeting helped the CCI team to
refine its research and to better integrate it with the other three. The CCI
research will study the accelerated aging test for paper at different
temperatures and relative humidities. CCI will also examine whether aging the
paper in stacks of 50 sheets or more (rather than testing individual sheets)
influences the test results. Again, the DP method developed by Elzbieta
Kaminska will be a key feature of the research. It is hoped that this work will
help to establish an aging test that can be incorporated into the ASTM
standard.
Through such efforts as the CGSB research and the ASTM project, CCI
researchers are taking part in the long-term goal of preserving our written
history.
