PRESELECTION OF HISTORICAL BOOKS IN THE PROCESS OF THEIR
STABILIZATION
M. Řeháková*, K. Vizárová, D. Jančiová, M. Valovičová, Š. Varga
Slovak University of Technology in Bratislava, Faculty of Chemical and Food Technology,
Bratislava, Slovakia
* corresponding author: milena.rehakova@stuba.sk
1. Introduction
The aim of this experimental study was to propose the methods of the qualitative classification of
historical books from 19th and 2Oth centuries from the point of view of their next preservation. A
special selection of book collection before the next deacidification, conservation and strengthening
processes is not necessary. The secondary effects and partial restrictions arc published only1-3. It
would be appropriate to develop a simple and fast realizable method for considering the books slate.
This method could also predict books behavior in the technological steps of preservation.
2. Experimental
Collection of 100 books of 20th century, kindly provided from Slovak National Library in Martin,
was studied. The following parameters were measured: square weight, thick of paper, the content of
paper pulp, pH of cold extract, surface pH of paper, the degree of sizing, folding endurance, tensile
strain by subsistent norms (ISO, STN)4-10 and lignin content by spectrophotometric measurements
of absorption at 280 and 457 nm (M40 with photometric ball, Carl Zeiss Jena), surface pH by
indicator papers (Machcrey-Nagel), performance stability from steel point. 15 measurements were
performed (at 3 pages localized in different places of book block and at 5 different zones on one
page) per one book. The following mathematical methods were used for statistical evaluation:
analysis of variance (ANOV A), point estimators of parameters in the model of analysis of variance,
nonparametric statistics - the Kruskal Wallis test, mullivariante analysis of variance (MANOVA),
correlation, cluster analysis.
3. Results and discussion
3.1 Acidity of paper
The acidity of ligno-cellulose materials was determined by 3 various methods of the pH value
measuring. The statistically significant difference was achieved between them, but their correlation
coefficient was determined as very high: 0.95-0.96. The dependence of pH value on the age of
books was determined and is showed in Fig. 1. The following results were obtained by statistic
evaluation: the position of the measured place on page influences the pH value, the location of the
page in the book does not influence the pH value, the book age influences the pH value. It was
found out that the text part was the most acidic area, internal edge near the back of the book was the
least acidic and the margins had almost the same pH values.
Figure 1: Average of pH of 20th century books sorted by their age. Standard deviation was ± 0.1
for cold extraction and surface pH method and ± 0.2 for pH indicator method.
3.2 Mechanical properties and degree of sizing
Results of mechanical properties measurement - tensile strength (tensile index Xt), folding
endurance (number of DF), break through endurance (puncture depth PD) always in the machine
direction (MD) and cross direction (CD) and their relations to the degree of sizing have shown, that
all of mechanical properties mutually displayed statistically significant correlation, especially in
case of MD with higher coefficient of correlation (0.45-0.75). That signifies that one of the
measurements (semi-destructive method in longitudinal line) is sufficed in practical monitoring.
The degree of sizing didn't show correlation with other mechanical properties.
We expected improvement of the mechanical properties with shorter age of books. The hypothesis
confirmed with the exception of some cases. The illustration of mechanical properties monitoring is
in Fig. 2.
3.3 Lignin
Dying experiment using fluorglucinol was used to estimate lignin content (OfL) and compared with
the spectral method (determination of remission at 280 -R280, and 457 nm - R457). The correlation of
these methods was significant with correlation coefficient 0.61 and dependence was following: %L
= 26.52 - 1.14 R280
Figure 2: Average of fold endurance of 20th century books sorted by their age.
4. Summary and conclusion
The others parameters showed neither statistical significance nor correlation with mentioned
properties. The classification of books based on acidity measurements (by indicator), mechanical
properties measurements (by steel point) and lignin content estimated (by spectrophotometry)
enabled their categorization into four groups (Fig. 3). Four kind of next book protection were
proposed. There were 14% of books in a very bad state and hand intercession was needed, 31 %
should be treated by deacidification and strengthening, 49% should be treated by deacidification
only and just 6% of books were in good state and no protection was needed. Monitoring of book
state in dependence of date of their origin is showed in Table 1.
Table 1: Categorization of 20th century books into the classes A-D.
Figure 3: Classification of books required protection; A -intercession of restaurators, B deacidification and strengthening, C - deacidification only, D - without protection.
5. References
1. W. Wächter, Bucher erhalten, pflegen und restaurieren, Hauswendel, Stuttgart 1997, ISBN 37762-0402-8, 203-241.
2. W. Sobucki, B. Drewniewska-Idziak, Survey of the preservation status of the 19th and 20"'
century collections at the National library in Warsaw, Restaurator, 2003, 24, 189-201.
3. J. Havermans, P. Marres, P. Defize, The development of a universal procedure for archive
assessment, Restaurator, 1999, 20, 48-55.
4. STN ISO 536 Paper and board. Determination of grammage.
5. STN ISO 534 Paper and board. Determination of thickness.
6. M. Souček, Zkoušení papíru, SNTL, Praha, 1977, 66.
7. STN ISO 6588 Paper, board and pulps. Determination of pH aqueous extract.
8. STN 500374 Testing of pulp and paper. Surface pH measurement of pulp and paper.
9. STN ISO 1924-2 Paper and board. Determination of tensile properties. Part 2: Constant rate of
elongation method.
10. STN ISO 5626 Paper. Determination of folding endurance.