A Guide for Conservators

Gerhard Banik and Irene Brückle
Paper and Water
A Guide for Conservators
ii
Contents
Paper and Water:
A Guide for Conservators
Contents
i
ii
Contents
Paper and Water:
A Guide for Conservators
Gerhard Banik
Irene Brückle
With contributions by
Vincent Daniels
Stefan Fischer
D. Steven Keller
Joanna M. Kosek
Reinhard Lacher
Anthony W. Smith
Alfred Vendl
Günther Wegele
Paul M. Whitmore
The printing was financially supported by the former Institute of Paper Conservation (IPC), today
part of Icon and ICCROM. The project 112 693 “Water in Paper” has been funded with support
from the European Commission. This publication reflects the views only of the authors, and neither
the Commission, nor other donors can be held responsible for any use which may be made of the
information contained therein.
Contents
iii
Routledge is an imprint of Taylor & Francis Group, an informa business
2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN, UK
Second and revised edition 2013
Copyright © 2011 & 2013, Gerhard Banik and Irene Brückle.
Published by Routledge. All rights reserved
The right of Gerhard Banik and Irene Brückle to be identified as the authors of this work
has been asserted in accordance with the Copyright, Designs and Patents Act 1988
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or
otherwise without the prior written permission of the publisher
Notice
No responsibility is assumed by the publisher for any injury and/or damage to persons
or property as a matter of products liability, negligence or otherwise, or from any use
or operation of any methods, products, instructions or ideas contained in the material
herein. Because of rapid advances in the medical sciences, in particular, independent
verification of diagnoses and drug dosages should be made
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
A catalog record for this book is available from the Library of Congress
ISBN: 0750668318
Graphic design and layout by Hellmut G. Bomm, Backnang, Germany
If not otherwise indicated all photographs are by Irene Brückle.
Cover photograph: Dietmar Katz, Berlin
iv
Contents
For F. Christopher Tahk
a visionary teacher
who enlightened generations of students
on the principles of science in conservation
Contents
v
vi
Contents
Paper and Water
Paper and Water:
A Guide for Conservators
Contents
1
Foreword from the perspective of the conservator
Kate Colleran
xiv
Foreword from the perspective of the conservation scientist
Jan Wouters
xv
Introduction
Gerhard Banik and Irene Brückle
xvii
User’s Guide
xxiii
Acknowledgements
xxix
Relevant Chemistry
1
Gerhard Banik
2
1.1 Basic principles
2
1.2 Covalent and ionic bonding
9
1.3 Electronegativity
12
1.4 Hydrogen bonding
14
1.5 Van der Waals forces
16
1.6 Carbon and glucose
16
Summary
21
Properties of Water
23
Gerhard Banik
2.1 Molecular structure
24
2.2 Surface tension
27
2.3 Viscosity
30
2.4 Volatility
31
2.5 Aggregate states of water
34
Contents
vii
Paper and Water
2.6 Dissolution/dissolving ability
36
2.7 Solubility of organic liquids in water
39
2.8 Ionic components in natural water
41
2.9 Hardness of water
43
2.10 Water purification
46
2.11 Purified water in paper conservation
52
Summary
52
Interaction between water molecules (DVD Video 2.1)
3
Dissociation of Water: Acids and Bases
57
Gerhard Banik
3.1 Dissociation of water
3.2 Acids and bases
4
58
+
61
3.3 The hydronium ion (H3O )
64
3.4 Strength of acids and bases
65
3.5 The pH concept
69
3.6 The pH of salt solutions
73
3.7 Buffer solutions – the carbonate buffer
76
Summary
78
Structure and Properties of Dry and Wet Paper
81
Irene Brückle
4.1 Cellulose structure
83
4.2 States of water absorption in cellulose
87
4.3 Gel and hysteresis properties of cellulose
94
4.4 The structure of dry and wet paper
97
4.5 The porosity of paper
109
4.6 The strength of paper in relation to its moisture content
111
4.7 Using the paper model
113
Summary
115
The structure of paper (DVD Videos 4.1–4.8)
viii
Contents
Paper and Water
5
Effect of Pulp Processing on Paper-Water Interactions
121
Irene Brückle
5.1 The native fibre
122
5.2 Chemical processes
127
5.3 Effect of chemical processing on fibre composition
130
5.4 Effect of chemical processing on fibre porosity
133
5.5 Effect of chemical processing on fibre reactivity
135
5.6 Beating and refining
138
Summary
140
Effect of water on different papers (DVD Videos 5.1–5.5)
6
Effect of Sizing on Paper–Water Interactions
145
Gerhard Banik, Irene Brückle, Reinhard Lacher
and Günther Wegele
6.1 Sizing technologies
146
6.2 Surface sizing with gelatine
150
6.3 Gelatine sizing in relation to paper properties
153
6.4 Internal sizing with rosin
156
6.5 Rosin sizing in relation to paper properties
160
6.6 Internal reactive sizing agents
162
6.7 Reactive sizing in relation to paper properties
164
6.8 Properties of sized paper in general
165
Summary
168
Effect of water on different types of paper (DVD Videos 6.1–6.7)
7
Paper Drying in the Manufacturing Process
173
D. Steven Keller
7.1 Water removal in paper manufacturing
175
7.2 Drying of individual lignocellulosic fibres
184
7.3 Drying of the fibrous network
190
7.4 Network shrinkage from fibre shrinkage
190
7.5 Structural factors that control shrinkage
192
Contents
ix
Paper and Water
7.6 Drying of the web in papermaking
197
7.7 Historical drying of paper
203
7.8 Rewetting and humidity response of paper
205
Summary
211
Formation of the paper structure (DVD Videos 7.1–7.3)
8
Paper Ageing and the Influence of Water
219
Paul M. Whitmore
9
8.1 Major changes in paper with ageing
221
8.2 Cellulose chain-breaking reactions
223
8.3 Discolouration reactions
238
8.4 The study of paper ageing
240
8.5 Stabilization of paper
246
Summary
248
The Introduction of Water into Paper
255
Irene Brückle and Gerhard Banik
9.1 Humidity
257
9.2 Humidity and paper
261
9.3 Liquid water and paper
264
9.4 Water transport mechanisms in paper
268
9.5 Paper in humid environments
271
9.6 Water introduction as conservation treatment
274
9.7 Paper and liquid water plus wetting agents
281
9.8 Factors influencing water absorbency of paper objects
283
Summary
285
Response of paper to wetting treatments (DVD Videos 9.1–9.9)
10
The Rate of Discolouration Removal from Paper by Washing
289
Vincent Daniels
x
Contents
10.1 The nature of discoloured material in paper
291
10.2 Paper washing compared with textile washing
292
Paper and Water
10.3 Diffusion and mass transfer
294
10.4 Moving discolouration out of paper
297
10.5 Effect of paper thickness on washing rate
299
10.6 Effect of treatment duration on washing rate
301
10.7 Effect of temperature on washing rate
304
10.8 Effect of previous moisture content on washing rate
306
10.9 Effect of surfactants on washing rate
307
10.10 Effect of deacidification on washing rate
309
Summary
310
Methods of controlling water flow (DVD Videos 10.1–10.4)
11
Washing Paper in Conservation
313
Joanna M. Kosek
11.1 Background
315
11.2 Washing principles
317
11.3 Preparatory considerations
320
11.4 Washing treatments
322
11.5 Immersion washing
322
11.6 Float washing
324
11.7 Blotter washing
329
11.8 Suction table washing
330
11.9 Combining washing methods
333
11.10 Treatment evaluation
334
Summary
335
Methods of directing water flow (DVD Videos 11.1–11.4)
12
Aqueous Deacidification of Paper
341
Anthony W. Smith
12.1 Ion-exchange properties of fibres
343
12.2 Deacidification principles
347
12.3 The chemistry of deacidification solutions
351
12.4 The alkalinity of deacidification solutions
373
12.5 Alkaline reserve
375
Contents
xi
Paper and Water
12.6 Protective effects of alkaline earth carbonates
377
12.7 Specification of aqueous deacidification processes
379
12.8 Practical considerations
380
12.9 Evaluating deacidification treatment
382
Summary
384
The ion-exchange capacity of oxidized cellulose
Neutralization of carboxyl groups (DVD Videos 12.1 and 12.2)
13
Drying Paper in Conservation Practice
389
Irene Brückle and Gerhard Banik
13.1 Water removal in papermaking and conservation
392
13.2 Principles of drying
393
13.3 Effects of free air-drying on sheet dimensional qualities
398
13.4 Preparatory considerations before conservation drying
404
13.5 Restraint-free or air-drying
406
13.6 Modified air-drying
407
13.7 Restraint-drying by pressure in a stack
408
13.8 Restraint-drying by pressure in a stack enforced
by friction
13.9 Lateral restraint-drying
410
411
13.10 Restraint-drying by pressure in a stack
under enforced air flow
411
13.11 Considerations for drying paper objects
413
Summary
414
Drying of albumen photograph (DVD Video 13.1)
14
Aqueous Treatment in Context
419
Irene Brückle
14.1 Considering risk and benefit of aqueous treatment
420
14.2 Focus on risk factors
423
14.3 Consideration of scientific principles in treatment
decision-making
14.4 Strategizing conservation decision-making
xii
Contents
427
431
Paper and Water
Appendices
1. Physical quantities and SI units
437
2. Tables of conversion
440
3. Measures of concentration
442
4. Periodic table (extract)
446
5. Water activity, chemical reactions and biological growth
447
6. Making proton migration and transfer visible
451
7. Simplified hygrometric chart
453
8. Hygrometric chart
454
9. Relative humidity (RH) over selected salt solutions
455
10. Setting up workshops
456
11. Suggested seminar schedule
459
12. Suggested seminar readings
461
13. Laboratory safety
464
14. Suggested seminar experiments
465
15. Methods for measuring the pH of paper
471
16. Methods for testing
the water absorption and wetting of paper
476
17. Identification of the reducing properties
of deteriorated cellulose
478
18. Test for lignin
482
19. Tests for paper additives and media binding agents
484
Glossary
491
Index
527
About the Authors
539
Contents
xiii
Paper and Water
Foreword
from the perspective
of the conservator
Washing in paper conservation has a long, if not always illustrious,
history. Once a routine, prescriptive process, conservators have too
often ignored its invasive nature. The loss of image definition, material and historical evidence were considered acceptable losses when
balanced with the perceived benefits of removing deterioration
products.
In the last 20 years or so two developments merged to inform and
change our understanding of this complex process. From the 1980s a
body of scientific work has been published on the theory and analysis
of washing paper and the associated loss or alteration of information,
and a more philosophical/ethical approach to conservation treatment
emerged, including the multiple meanings of objects and their potential loss through the processes of chemical alteration.
Whilst the body of scientific literature was growing, the gap between theory and practice widened. The application of scientific
investigation to practice is one of the most difficult areas of conservation and its teaching, particularly when unquestioned practice has
been embedded over a long period of time.
In 1959 C. P. Snow, the British scientist and writer, delivered his
famous lecture, ‘Two Cultures and the Scientific Revolution’, in which
he described what he called a ‘gulf of mutual incomprehension’ between scientists and humanists. He described the reason for the loss
of understanding between the two cultures and its inherent dangers
as stemming from ‘the two cultures can’t talk to each other’. He
warned that the loss of a common culture ‘is leading us to interpret the
past wrongly, to misjudge the present, and to deny our hopes of the future’. He could have been thinking and talking about conservation –
and in particular, the gulf between practice and the science that informs it.
It is this gulf that Paper and Water: A Guide for Conservators aims
to bridge. This work provides us with the tools to understand a whole
range of interactions between paper and water; it clears our minds of
the misunderstandings of the past and provides new theoretical information to underpin practice. It is a book that should be on the desk
of every paper conservator and teacher of paper conservation.
It has been a long journey – the authors are to be congratulated
for their contributions and the editors for their vision and endurance
in bringing this compendium into being.
Kate Colleran
London 2009
xiv
Foreword from the perspective of the conservator
Paper and Water
Foreword from the
perspective of the
conservation scientist
‘The centre of the sphere of waters is the true centre of the globe of our
world, which is composed of water and earth, having the shape of a
sphere. But, if you want to find the centre of the element of the earth,
this is placed at a point equidistant from the surface of the ocean, and
not equidistant from the surface of the earth; for it is evident that this
globe of earth has nowhere any perfect rotundity, excepting in places
where the sea is, or marshes or other still waters. And every part of the
earth that rises above the water is farther from the centre.’
Leonardo da Vinci. Notebook 934. In: The Notebooks
of Leonardo da Vinci, J. P. Richter (ed.), 1880.
Water has one of the most simple chemical compositons known:
just two hydrogen atoms combined to one oxygen, and that is it. But
it is exactly this particular composition which gives water such a
prominent position when it is in close contact with other materials.
One of those materials is cellulose. And it is the combination of that
cellulose with water and other materials that we call paper.
We can see the water of the oceans. Also paper contains water, on
average some 8% by weight, but that water we cannot see. When
subjected to heat, paper loses water and it is said to dry. However, it
will never be dry, because complete removal of the water will never
be achieved without losing the paper.
Water confers to paper desirable properties such as suppleness,
easy folding and pleasant feel. Water is essential in conferring to
paper most undesirable properties, such as degradation caused by
acidification, which may lead to ultimate loss of the sheet.
Water needs to be added to paper to measure its acidity, its pH.
Why? Paper already contains water. If that amount is not enough to
measure the pH, how do we then extrapolate the measured pH of
paper in an amount of water which is several orders of magnitude
higher than the one naturally present in the paper, to that degree of
acidity which must be assumed to be naturally present in the paper,
without the addition of the extra water needed for the pH measurement?
Water is essential in the paper production process; water causes
damage to paper during natural ageing processes; water will often be
used in excess to perform paper conservation treatments.
The controversial nature of the statements given does not undermine their trueness. But how to explain the controversies to parties
that are involved in the study and care of paper artefacts? And how to
respectfully offer scientific knowledge and experience to those parties that have little or no scientific background, yet are eager to know
because knowledge gained will improve practice?
Foreword from the perspective of the conservation scientist
xv
Paper and Water
The pathway of how to proceed has been clearly established in this
book by Gerhard Banik and Irene Brückle. They have started from
nearly scratch and have gradually built up knowledge to help understand extremely complex processes such as paper manufacture, ageing and conservation.
Difficult physical and chemical terms, parameters, units and concepts are clearly explained in a series of chapters and paragraphs that
steadily work from basis to objectives, and the authors have not
missed any chance to gradually apply the knowledge gained when
digging deeper into the understanding of the material paper, its properties, its ageing and its conservation. I am a conservation scientist
myself and have gained over the years a fairly good knowledge of the
technology and chemistry involved with the production, ageing and
conservation of objects, mainly composed of natural materials, such
as paper. Nonetheless, I have been confronted in this book with
knowledge and insights that I had lost, maybe even never had.
Therefore, I am convinced that this book will be a useful source of
knowledge to any party involved in the multi- and interdisciplinary
approaches needed to critically study, select and execute protocols
for the safeguarding of cultural heritage in general, and particularly of
its very important constituent – paper.
Jan Wouters
Zwijndrecht, Belgium, 2009
xvi
Foreword from the perspective of the conservation scientist
Paper and Water
Introduction
‘An organic chemist’s perspective – theoretical and experimental –
focuses primarily on molecules. By contrast, the biologist looks at entire
systems: a cell; a leaf; a tree.’
C. Djerassi, Cantor’s Dilemma, London: Penguin Books, 1991, p. 7.
The idea for this textbook arose when we realized in our respective
paper conservation teaching practices the dire lack of comprehensive
discussions that would integrate two separate spheres: that of the
conservation scientist and that of the conservator. As we can learn
from the famous scientist Carl Djerassi, the perspectives of two distinct disciplines, even when they focus on the same problem, must
naturally be different, if not contrasting. Although concerned about
the same subject, the preservation of cultural property, the conservation scientist looks at objects from a submicroscopic angle, while the
conservator is – and must be – concerned about the entire object. To
bring both perspectives into one plane of discussion is the essential
idea behind this book. Scientific theory is thus discussed within an
applied conservation context, and vice versa. Creating an interdisciplinary systematic perspective necessarily requires the omission of
certain detail discussions – chemical formulae, mathematical equations on the one hand, and treatment case studies on the other hand.
Preserving a generalized perspective will, so we hope, make the content of the book most universally applicable in different conservation
contexts.
Water is the constant companion of cellulosic materials. It is
present in living plant fibres and remains present in harvested plants;
it swells, disperses and mats fibres during papermaking. It further influences the properties affecting handling and use of paper products.
Without water, paper would not have its widely appreciated properties of pliability and strength. In conservation, water is arguably the
most versatile and powerful manipulating agent of paper; it swells and
plasticizes its fibres, it can be used to transport undesired substances
out of paper, and beneficial substances into paper. Overall, it can be
said that the intimate association of water with paper carries many
positive aspects. However, it is also readily acknowledged that any
uncontrolled and excessive interaction of water with paper carries the
risk of damaging it in the short and long term. Controlling the water
content of paper objects is therefore key to assuring their longevity
and safety.
Three principal movements of water in paper at first glance seem
to be simple enough: water is absorbed into paper, it is desorbed
from paper, and it can migrate inside the fibrous paper matrix from
one location to another. However, the patterns of interaction are
Introduction
xvii
Paper and Water
more complex than accounted for by this statement for several reasons. First of all, cellulose loves water, i.e. is hydrophilic, which is why
it shows a dynamic response to environments that allow it to take up
or force it to give up water. Second, except at the smallest dimensional level of molecular units, paper is not at all a homogeneous material. Pores disrupt its fibrous matrix, and paper contains substances
other than cellulose that are either a natural part of fibres or are
added by the papermaker or subsequent users. Third, paper is chemically and physically altered as it ages over time. Each of these factors
influences the ability of paper to interact with water. And fourth, water interacts with paper differently depending on its state of matter,
vapour, liquid or ice. Absorption, desorption and transport of water
or aqueous solutions in paper are influenced by a number of key factors that each require separate consideration if they are to be controlled in conservation.
In explaining the interaction between paper and water we want to
accomplish several goals: to provide a focus on the scientific principles that underlie all paper–water interactions; to define thereby a
level of discussion that is universally applicable and remains distinct
from any individual object; and to create a comprehensive introduction to the paper–water topic by drawing knowledge from other scientific fields outside of conservation to generate tailored interpretations of relevant conservation issues. We hope this will enrich the discussion of the scientific foundations of conservation with regard to
the effect of water on paper.
These ideas already supported the inception of the project in the
year 2000, but gained greater clarity while the manuscript gradually
took shape and its content was reworked throughout the subsequent
years. During this time, and with the generous support of the European Commission (2002–2005), we also had the invaluable opportunity to test our concepts in a number of international venues. We had
many fruitful discussions both with students of conservation as well
as with conservation experts, including practitioners, educators and
scientists, some of who became contributing authors.
Some of the key decisions that went into the preparation of the
material presented here deserve mention because they concern pivotal questions that were raised along the way. These questions invariably echoed general concerns as to the position of science relative to
practice in conservation. We will give some answers concerning essential points, acknowledging that they do not reflect the full scope of
all past conversations.
Let us first consider how science relates to conservation as a profession. In the general sense, science implies knowledge about the
xviii
Introduction
Paper and Water
universal laws of nature according to which the materials in our physical world function; the scientific enterprise concerns the ‘pursuit of
knowledge covering general truths or the operations of fundamental
laws’ (Encyclopedia Britannica 2004). In conservation, the word
science is commonly connected with areas termed ‘conservation science’ or ‘archeometry’, which are specialized branches of the natural
sciences that seek to illuminate the natural laws by which the materials of cultural objects and conservation function, centred on methods
of instrumental and laboratory analysis. Conservation science may
thus support the preservation, conservation and study of objects.
Scientific research must be transferable to conservation practice if
it is to ensure the longevity of objects and secure the various forms of
their use. It thus concerns a research area defined by conservators,
since they set the goals for conservation activities and are responsible
for the transfer of new techniques into conservation practice. They
also judge whether – and how successfully – these goals are attained.
This necessitates involvement in two branches, one of which concerns
the material and historical study of objects, and the other of which
concerns the advancement of conservation technology that improves
the quality of preservation and treatment. Improving conservation
measures is centred on applied research. The two branches are interrelated, as an improved material understanding of the object necessitates a more differentiated conservation approach.
Education of conservators requires the integration of different
knowledge areas including material sciences, manual skills and historical scholarship. The spectrum of conservation expertise is, however,
sometimes not understood by outsiders in its full complexity, and
expectations of conservation may be not as differentiated as is warranted by the significance of any material intervention on cultural
property. The most pertinent cause may lie in the fact that, in conservation practice, and especially in treatment, which is the oldest
established root of conservation, the complexity of reasoning tends
to be concealed behind the seemingly simple and observable handson work. The manual skills of conservation still look to some unsuspecting observers much like the craft and restoration traditions from
which modern paper conservation sprang when it was included in
academic education. The scientific basis of conservation practice,
which originally shifted it from craft to academic profession, is today
of course long established. However, the integration of scientific
knowledge with conservation practice is still not universally accomplished and therefore remains an ongoing concern. To this ongoing
process this book intends to make a contribution.
Introduction
xix
Paper and Water
Most of the scientific principles that concern the functioning of
materials of interest to conservation were formulated in other scientific fields before conservation took an interest in them. Conservation
therefore has borrowed extensively from chemistry, physics and engineering. However, to make knowledge of these other disciplines effective in conservation requires more than picking and choosing from
these disciplines. Quoting a graph that was relevant in its original context does not mean that it reveals its full potential in the same way in
a conservation environment. It may very well remain on the fringes if it
does not undergo translation from one language to another, from one
interpretative context to another, and from one presentational style
to another. Unless this effort is made, it is often not clear why science
information should matter in making conservation decisions. Science
that remains only the talk of scientists but is not reflected in the wider
field of conservation has been quite aptly termed ‘endoscience’ by
Salvador Muñoz-Viñas in his book Contemporary Theory of Conservation (2005). We are intent on eliminating this gap by creating a knowledge base that contributes to the emancipation of scientific conservation practice. We took our orientation from Anglo-Saxon traditions
of transmitting knowledge, even of the most profound kind, in as accessible a manner as possible, as Michael Munowitz demonstrated in
his book Knowing: The Nature of Physical Law (2005).
In this book, the natural science and conservation concepts had to
undergo interpretation to strengthen their significance in the context
of conservation. This required omissions that made us continuously
aware of the danger of oversimplification. However, leaving certain
specialist discussions to referenced works was a calculated effect that
created the room for the descriptive breadth needed to explain principle ideas.
It may be asked why we decided to omit a discussion of coated
paper. After all, it is ubiquitous in industrial papermaking since the
19th century and exists in early and non-western papers. The reason
is that coated paper behaves much differently from uncoated – even
from sized – paper because it carries a layer of pigment mixed with
binder that make it a different entity to deal with altogether. In fact,
with regard to its reaction to water, coated paper can be compared
to any media-coated paper including the Early Renaissance papers
prepared by brush-coating with pigments. The extreme sensitivity of
most coated papers to water results principally from two reasons.
The binder may swell up to the point of dissolving or at least altering
the optical appearance of the coating, thereby severely endangering
media that lie on top of it. The coating may not expand or shrink as
much as the base paper, causing either paper curl or flaking of the
xx
Introduction
Paper and Water
coating layer. In sum, because coated paper is a special category of
paper requiring many special considerations when exposed to aqueous environments, it requires also special considerations that are
not the goal of this book.
Another key question concerns the representation of treatment of
paper objects in this book. Some discussants considered it dangerous to illustrate any ‘real’ objects in a treatment situation because it
was felt that this would stimulate thoughtless imitation on the part of
the uninformed, and would raise controversy about preferred treatment approaches among professionals. Without necessarily agreeing
with all of these points, we did, however, come to the conclusion that
the focus of the book was to remain throughout on a level where the
general principles were to be discussed and that this level was also to
be maintained with regard to treatment. This inspired us to develop
samples or mock-ups in the form of papers impregnated with watersoluble red food dye for our treatment workshops. The model objects served as stand-ins for real objects. They consist of paper impregnated with a highly water-soluble red food dye. Compared to
real-life treatment action photography, they allow a more consistent
and less distracting view of key operations that cause the dissolution
and transfer of water-soluble materials.
It was also asked how can one write about paper and water in a
general way when ‘every object is different’. The uniqueness of objects alluded to in this question concerns a different realm of discussion that involves the assessment of the cultural, e.g. historical, documentary, or aesthetic value of the object, which is a key part of curatorial expertise and which is to be supported through conservation
expertise. Technically, however, paper is not unique because only a
few key variables in its composition and condition determine its response to water. The cultural value of paper objects is irrelevant in
understanding this relationship. However, the scientific principles of
the paper-water relationship are indeed relevant for formulating
overall conservation strategies for paper objects within a cultural context. Chapter 14 provides selected examples that demonstrate the
ways in which scientific principles discussed in this book can be made
applicable in the assessment of objects. Decisions made about the
treatment of objects must remain the prerogative of the conservator
who is responsible for the object in the respective context in which it
is preserved and used. In keeping a general perspective, we hope to
make this book useful in different contexts in which artworks, archive
documents or library materials are treated. This may inspire readers
to adapt and expand the creative use of water in paper conservation
and communicate their observations.
Introduction
xxi
Paper and Water
We were privileged in that distinguished experts in conservation,
science and papermaking technology brought their vast knowledge
to this book, not only by writing individual chapters, but also by discussing the direction and content of the book with us over the course
of time. Günther Wegele (†) from Klug Conservation, Immenstadt,
Germany, and Reinhard Lacher from RL Consulting, Much, Germany,
contributed to Chapter 6 on paper sizing technology. D. Steven Keller,
Associate Professor at Miami University, Miami, Ohio, wrote Chapter 7
on the principles of paper drying technology. Paul M. Whitmore, Director and Conservation Scientist at the Research Center on the Materials
of the Artist and Conservator at the Carnegie Mellon University in
Pittsburgh, in Chapter 8 discusses the influence of water on paper
ageing. Vincent Daniels, Emeritus Researcher at The British Museum,
London, writes about the effectivity of washing mechanisms in Chapter 10. Joanna M. Kosek, Head of the Western Section of paper conservation at The British Museum, London, presents the principles of
aqueous washing methods in Chapter 11. Anthony W. Smith, formerly Principal Lecturer in Science and Course Director of the MA
programme in paper conservation at the University of the Arts, London, explains the principles of deacidification in Chapter 12. Visualization of the cellulose–water interaction was made possible by Alfred
Vendl, Director of the Institut für Kunst und Technologie at the Universität für Angewandte Kunst in Vienna and his co-worker Stefan
Fischer, who created most of the animations and videos. Additional
animations were graciously contributed by: Rune Holmstad at Södra
Cell Tofte, Tofte, Norway; Olivier Masson, Masson Pictet Boissonas,
Zurich, Switzerland; Mark Miller, University of Cambridge, Cambridge, UK; and Hiroki Nanko, Insight Technology International, LLC,
Atlanta, GA, as well as both Paul Messier, Conservation of Photographs
and Works on Paper, Boston, MA, and Timothy Vitale, Emeryville, CA,
USA. We are very grateful to all of our contributors for their willingness to embark on this project, and for their wise council throughout,
we are very grateful. Special commendation is also owed to them for
their patience in supporting the process of fitting all of the parts of
the book together, as they had to endure the slowly grinding motions of the manuscript machinery over the course of several years. It
gradually became a universally acknowledged truth that, disregarding
the inevitable logistical roadblocks, unifying the presentation required
its own thinking time. In the end, it became clear that the book could
not have been produced in its present form without this prolonged
and communal effort.
Gerhard Banik
Wien
xxii
Introduction
2010
Irene Brückle
Stuttgart
Paper and Water
User’s Guide
Book structure
This book is structured in several sections that each covers one or
more chapters. It includes basic scientific concepts relating to paper
and water (1–4), key papermaking variables that influence the paperwater relationship (5–7), dynamic paper-water interactions that play
a role in paper ageing and treatment (8 and 9), technical applications
in treatment (9–13) and the conservation context (14). There are
three sections within the appendices: Appendices 1–3 contain general
information such as SI units; Appendices 4–9 contain supplementary
information for individual chapters, and Appendices 10–19 present
suggestions for seminars, including selected experimental and testing
procedures.
The accompanying DVD contains short animations and video clips
that visualize special features of paper–water interactions. The animations are based on drawings and are closely related to the printed
text. A few videos illustrate the interaction of paper and water in relation to conservation treatment, without providing guidance on treatment. Reference to these features is made in respective chapters.
Models, visualization,
colour code
The visual models were designed to facilitate understanding of natural laws and principles in chemical formulae or mathematical equations. Models, as may be remembered, do not replicate reality, but
present a selective view of it that judiciously highlights certain features and, for the sake of clarity, suppresses others. Models also
translate abstract facts into images that make them easier to grasp.
This tendency of models to omit certain details is permissible as long
as they avoid oversimplification that would lead to the misunderstanding of the reality they represent. In our case, the complex realities of paper conservation are viewed selectively, which means leaving
out certain individual particulars of paper objects, and giving centre
stage to those fundamental scientific principles that always dominate
the mechanisms of interaction between paper and water.
Entry of water into the paper matrix causes changes that can be
traced from the molecular to the sheet level. Illustrations and videos
therefore intend to visualize the connection between the sub-microscopic and the macroscopic world.
User’s guide
xxiii
Paper and Water
gas
water vapour
liquid
Water is represented in blue. It is shown
in its molecular shape with respect to its
state of matter, either as globule in the
gaseous state, as angled molecules in the
liquid state, and in a crystalline arrangement in the solid state; hydrogen bonds
are represented by blue dotted lines.
solid
gas
water vapour
Different shades of blue indicate the
presence of water in the liquid state (dark
blue) and in the gaseous state in humid
air (light blue).
liquid
Non-polar groups in organic molecules,
such as the ethyl group in ethanol (ethyl
alcohol), are unable to interact with polar
water molecules. These groups are indi-
cated by a yellow colour. The polarity of
the hydroxyl group (OH) bound to
organic residues such as (C2H5) are indicated by a blue colour.
The basic building block of cellulose is
anhydroglucose consisting of five carbon
and one oxygen atom arranged in a sixmembered ring. The core of the anhydroglucose rings neither attracts nor accommodates water molecules. It is given
a yellow colour.
The interaction between cellulose and
water is limited to the hydroxyl groups
attached to the ring but pointing outwards. These polar functionalities (blue)
establish hydrogen bonds with water
molecules indicated by the blue dotted
line.
From every cellulosic surface polar hydroxyl groups point outwards attracting
water molecules and establishing hydrogen bonds (blue dotted lines). The bulk
cellulosic matrix of the dry papermaking
fibre or dry paper is given a beige colour.
Moist or wet paper is indicated by a
greenish colour.
xxiv
User’s guide
Paper and Water
In a central model, different levels of
organization ranging from the cellulose
chain to the paper sheet are shown. The
water absorbed into the amorphous areas
of cellulosic matrices is indicated by the
blue colour. Dry cellulose and dry paper
are given a beige colour.
I molecules
II fibrils
III lamellae
IV fibre
V fibre network
VI sheet
The dynamics of paper–water interaction
are shown in multi-step illustrations, in
which different shades of blue illustrate
the migration of water into the paper matrix. The colour of dry paper is beige, and
the colour of humidified or wetted paper
is greenish.
dry paper
water vapor
moist paper
water vapor
liquid water
User’s guide
xxv
Paper and Water
Non-cellulosic components that are
naturally present in papermaking fibres or
papermaking additives that make paper
resistant to water absorption are given a
brown colour. Hemicelluloses mixed with
lignin in the cell wall are indicated in
green.
lignin
sizing particles
(alum/rosin sizing)
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
absorption-restistant
paper
Acids are indicated by orange colour;
bases are purple.
acid
hydronium ion
base
hydroxide ion
The movement of water-soluble discolouration and acidic degradation
products in paper are illustrated with
orange arrows.
xxvi
User’s guide
Paper and Water
Treatment Simulation
The mechanisms of aqueous treatment of
paper objects are illustrated with the help
of standardized mock-up paper samples
that were dyed with the food dye Azorubine (E 122) to demonstrate the migration
of water-soluble substances during treatment. The soluble dye not only represents the discolouration one desires to
remove, but also serves as a reminder that
original water-soluble materials such as
inks may be dislodged during aqueous
treatment.
The dynamics of paper–water interactions
are presented in animations and videos.
The animation of which the still image is
shown here features the accommodation
of water in the cellulose matrix. The
colour code for beige (cellulose matrix)
and water (blue) of the animations correlates with the book’s model drawings.
The videos show the response of different
types of paper to water.
User’s guide
xxvii
Paper and Water
Acknowledgements
This book is largely the outcome of a research grant generously
provided to the Studiengang Restaurierung und Konservierung von
Graphik, Archiv- und Bibliotheksgut at the Staatliche Akademie der
Bildenden Künste Stuttgart by the European Commission within
the framework of its Leonardo da Vinci Programme between 2002
and 2005. The goal of the project was to develop didactic material
for the education of paper conservators. It gave us the opportunity
to closely cooperate with the International Centre for the Study of
the Preservation and the Restoration of Cultural Property (ICCROM),
based in Rome, and the two most important European professional
bodies of paper conservators, the Institute for Paper Conservation
(IPC) and the Internationale Arbeitsgemeinschaft der Archiv-, Bibliotheks und Graphikrestauratoren (IADA). Through these project
partners, we were able to refine the content of our project in
different conservation education and training activities for students,
practising conservators, and distinguished educators from Europe,
America and Asia. More than 15 seminars, each chaired by a scientist and conservator, were held in Stuttgart, Berlin, London, Oxford,
Vienna and Rome. Many of these events were evaluated through an
independent institute, NAVREME. Additionally, but separate from
European Commission funding, the project was also presented to
conservation constituents in Ascona, Switzerland, Buffalo, San Francisco and Austin, USA.
We would like to express our gratitude to the representative of
the Leonardo Programme of the European Commission, Klaus Fahle,
for his interest in the project and his continuous support, Bernd
Baumgartl for the evaluation of the seminars, and Klaus Behrbohm
for his enormous help in administration of the project and holding
the partnership together. We are indebted to the former DirectorGeneral of ICCROM, Nicholas Stanley-Price, and to Katriina Similä,
Project Manager, Collections Unit, of ICCROM and her assistant,
Isabelle de Brisis, for their input in the project, the professional
preparation of the ‘Train the Trainers’ seminar (2004) and Evaluation
of the Symposium of Experts (2005), both held at ICCROM in Rome,
and Mónica García Robles and Jennifer Copithorne of the Office of
Communication and Information. We are indebted to Kate Colleran,
former Chair of IPC, and Markus Klasz, former Chair of the IADA,
who both prepared and organized seminars given to distinguished
conservators hosted by the National Archives in London (2004) and
the Institut für Papierrestaurierung in Vienna (2004).
A grant provided by the Foundation of the American Institute for
Conservation of Historic and Artistic Works through its Samuel H.
Kress Foundation Publication Grant to Irene Brückle, then at the
Acknowledgements
xxix
Paper and Water
Art Conservation Department at Buffalo State College, State University of New York, was essential in supporting the initial phase of the
project during a sabbatical (2001). We would like to express our gratitude for this initial seed money that allowed the creation of core sections.
Our greatest debt of gratitude is to those specialists who consistently encouraged us and shared their experience in conservation
education or paper physics and chemistry. Foremost among these
colleagues is Kate Colleran, who brought in her enormous educational and practical experience and through many stimulating discussions
contributed much to the finalization of the project. We also owe a
great debt to F. Christopher Tahk, the former Director of the Art
Conservation Department at Buffalo State College, for providing expertise, advice and help, especially during the crucial instigation
phase of the project. We are grateful to Dieter Klemm, former Head
of the Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena for an insightful discussion
in the autumn of 2001, that directed us to basic concepts for the illustrations modelling the molecular dynamics in the relationship of cellulose and water, to Philip Luner, former Faculty at the Empire State
Research Institute at the State University of New York College of Environmental Science and Forestry, for an early review of the project,
and to Guido Dessauer, Professor at the Institute of Paper, Pulp and
Fibre Technology, Graz University of Technology for his substantial
contributions on paper technology and ageing characteristics of
paper. We are indebted to Antje Potthast and Thomas Rosenau, both
Professors at the Department of Chemistry of the University of Life
Sciences Vienna, for providing their vast expertise in cellulose chemistry, numerous fruitful discussions and critical review of Chapters
1–8. Our special thanks go to Margaret Holben Ellis, New York University, John Krill, formerly University of Delaware, and Dan A. Kushel,
Buffalo State College, for their insightful comments as experienced
educators.
We would like to thank Mark Miller at the University of Cambridge;
Olivier Masson at Masson Pictet Boissonnas, Gemälde- und Graphikrestaurierungen AG, Zürich; Hiroki Nanko at Insight Technology
International, LLC, Atlanta, GA, USA; Rune Holmstad at Södra Cell
Tofte, Tofte, Norway, as well as both Paul Messier, Conservation of
Photographs and Works on Paper, Boston, MA, and Timothy Vitale,
Emeryville, CA, each of whom granted rights to include additional
animations or videos that they conceived and created that enabled us
to illustrate special features of molecular dynamics relating to paper
materials.
xxx
Acknowledgements
Paper and Water
There are many other experts, colleagues and friends we would
like to thank because they supported this venture in one or more
ways, sharing their expertise, helping us to gain otherwise inaccessible
materials, granting the rights for illustrations and photographs, or
who critically read various sections of our drafts: Barbara Appelbaum, Cathleen A. Baker, Timothy D. Barrett, Albrecht Becker,
Holm Bevers, Jochen Bomm, Craigen Bowen(†), Elisabeth Brauner,
Elisabeth I. Coombs, Georg J. Dietz, Ilse Entlesberger, Debra Evans,
Bernhard Fischer, Marie-Luise Frank, Ulrike Gauss, Eva Glück,
Andrea Giovannini, Taiyoung Ha, Oliver Hahn, Ulrike Hähner, Imke
Henningsen, Doris Hess, Hildegard Homburger, Enke Huhsmann,
Eva Hummert, Hilary A. Kaplan, Stephanie M. Lussier, Manfred
Mayer, Debora D. Mayer, Elke Menzel, Karin Petersen, Meike Schmidt,
Herbert Sixta, Janice M. Schopfer, Theresa J. Smith, Martin Strebel,
Bas Van Velzen, Judith C. Walsh, Jeffrey Warda and Jan Wouters.
Several students in paper conservation from the Staatliche
Akademie der Bildenden Künste Stuttgart worked on projects in
connection with topics presented in this book: Roland Reinke and
Ingeborg Fries investigated the wetting behaviour of paper, Roland
Damm the migration of water in paper stacks, Katrin Schröter and
Eva Hummert humidification techniques. Petra Buchschuster, Eva
Glück and Meike Mentjes experimented with techniques of drying
paper objects. These projects were co-supervised by staff members
and external advisors: Andrea Pataki, Regina Schneller, Ernst Becker
and Susanne Ruf. Research supporting the project was also undertaken by students of the Art Conservation Program at Buffalo State College: Heather Hamilton investigated washing procedures for paper
objects with the help of dyed paper samples; Rachel Freeman studied
gelatine loss due to water exposure of gelatine-sized papers and
Jeffrey Warda tested aqueous solutions. We also wish to acknowledge
the constructive feedback of students of the Staatliche Akademie der
Bildenden Künste Stuttgart during a series of seminars from 2003 to
2009, and students of the Art Conservation Department at Buffalo
State College, for their respective feedback between 2002 and 2004.
Special gratitude is extended by Irene Brückle to her former
colleagues James F. Hamm, Dan A. Kushel, F. Christopher Tahk, and
Jonathan Thornton at the Art Conservation Department at Buffalo
State College. Their knowledge and dedication will not be forgotten.
The support of Heinrich Schulze Altcappenberg at the Kupferstichkabinett, Staatliche Museen zu Berlin, who graciously hosted an editorial meeting in the spring of 2006, is also gratefully acknowledged.
She also wishes to thank Hubert Locher at the Phillips Universität
Marburg. Diana McNerney and Marjorie Lord from Buffalo State
College provided unrelenting support.
Acknowledgements
xxxi
Paper and Water
D. Steven Keller extends his gratitude to Philip Luner as a scholar,
mentor and friend from the Empire State Research Institute at the
State University of New York College of Environmental Science and
Forestry.
Joanna M. Kosek wishes to acknowledge Steve I’Anson, Lecturer
at the School of Materials, University of Manchester for continuous
advice on scientific matters; Alan Buchanan, Conservator in Private
Practice for lending his support on the suction table washing discussion; as well as Ken Uprichard, Head of Conservation, Department of
Conservation and Scientific Research, The British Museum; Vincent
Daniels, Emeritus Researcher, The British Museum; and Kate Colleran
for editorial advice.
Anthony W. Smith would like to thank Kate Colleran. Her encouragement and unflagging support were greatly appreciated.
Paul M. Whitmore wishes to thank the Art Conservation Research
Center at Carnegie Mellon University, where the experimental programme in paper research produced some of the results described
in Chapter 8; as well as John Bogaard, Catherine Stephens and Sang
Lee, who performed that experimental work at the Center; the
Andrew W. Mellon Foundation, who sponsored that paper research;
and Robert Feller, who as Director of the Research Center initiated
the paper research programme, and who graciously read and edited
Chapter 8.
We are thankful to Elsevier, especially Mike Travers, Susan Li and
Rhys Griffiths for their professional support in editing and printing
the book.
The printing of the book was supported by extra funding we
received from ICCROM and IPC, today part of ICON.
Last but not least we are indebted to our superb graphic designer
Hellmut G. Bomm, Backnang, Germany, for expertly and patiently
generating the customized drawings through their many revisions
over 10 years and for realizing the layout of this book.
xxxii
Acknowledgements
ii
Contents
Water is present when paper is made and when it ages. Water also serves many essential
functions when deteriorated paper is treated by conservators. Drawing on paper industry and
scientific research, Paper and Water examines closely the relationship between this common
cellulosic material and H 2O.
The interaction between paper and water is a topic of primary importance for every conservator
working with paper objects and other cellulose-based materials. Throughout the book, the theories
that underlie the effects of water on paper, and their practical application, are presented in relation
to the processes of conservation. Paper and Water is a reference and teaching compendium for
conservation professionals involved in the preservation of paper objects in archives, libraries and
fine art museums around the world. Written by experts in paper conservation, this book and
DVD aim to serve a rapidly expanding profession.
The book includes:
integrated knowledge from disciplines of paper engineering, conservation science
and conservation practice
hundreds of full colour illustrations to aid understanding
DVD featuring videos and animations, most of which exclusively produced for this
book, and a selection of key illustrations from the book to support teaching
With contributions by:
Vincent Daniels
D. Steven Keller
Alfred Vendl
Stefan Fischer
Reinhard Lacher
Joanna M. Kosek
Anthony W. Smith
Günther Wegele
Paul M. Whitmore