Conservation of Wood Artifacts: A Handbook

585 Pages·2001·11.69 MB·English

by  Dr. rer. nat. Achim Unger

Natural Science in Archaeology
Series Editors: Bernd Herrmann · Gunther A. Wagner
Springer-Verlag Berlin Heidelberg GmbH
A. Unger · A.P. Schniewind · W. Unger
Conservation
of Wood Artifacts
A Handbook
With 69 Figures and 35 Tables
Springer
Series Editors
Professor Dr. Bernd Herrmann Professor Dr. GUnther A. Wagner
Institut fiir Anthropologie Institut fiir Archaeometrie
Universitlit Gottingen Max-Planck-Institut fiir Kernphysik
BiirgerstraBe 50 Saupfercheckweg 1
37073 Gottingen, Germany 69117 Heidelberg, Germany
E-mail: [email protected] E-mail: [email protected]
Authors
Dr. rer. nat. Achim Unger Professor Dr. Arno P. Schniewind
Staatliche Museen zu Berlin Forest Products Laboratory
Rathgen-Forschungslabor University of California at Berkeley
SchlossstraBe la 1301 South 46th Street
14059 Berlin, Germany Richmond, CA 94804-4698, USA
E-mail: [email protected] E-mail: [email protected]
Professor Dr. rer. nat. Wibke Unger
University of Applied
Sciences Eberswalde
Wood Science and Technology
Alfred-Moller-StraBe 1
16225 Eberswalde, Germany
E-mail: [email protected]
ISBN 978-3-642-07480-6
Library of Congress Cataloging-in-Publication Data
Unger, Achim.
Conservation of wood artifacts : with 69 figures and 5 tables I A. Unger, A.P.
Schniewind, W. Unger.
p. em. - (Natural science in archaeology)
Includes bibliographical references.
ISBN 978-3-642-07480-6 ISBN 978-3-662-06398-9 (eBook)
DOI 10.1007/978-3-662-06398-9
I. Archaeology -Methodology. 2. Woodwork - Conservation and restoration - Handbooks, manuals, etc.
3. Wood -Preservation - Handbooks, manuals, etc. 4. Wood - Chemistry -Handbooks, manuals, etc.
5. Antiquities -Collection and preservation - Handbooks, manuals, etc. 6. Cultural property - Protection.
I. Schniewind, Arno P. II. Unger, Wibke. III. Title. IV. Series.
CC137.W6 U54 2001
702.8'8 - dc21
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We owed to wood so very much. We wasted nothing of it.
It held up our houses and fueled our fires. We made our tools
from it, we made our vessels from it.
When we brought down a tree, it was long work to make it
fit into our world of useful things. But it brought us beauty.
Early People Exhibition
Museum of Scotland, Edinburgh
Preface
The impetus for this book was the desire to systematically organize the extant
literature on the conservation of cultural property made of wood, from its
beginnings before the Christian Era to the year 2000. Various published
reviews and monographs, including Holzkonservierung (Wood Conserva
tion) published by the senior author in 1988, have appeared over the years,
especially in English and in German. They have provided exemplary treat
merit of individual areas or aspects of wood conservation, but a comprehen
sive, up-to-date exposition of historic and current developments has been
lacking. The diverse professional fields of the authors, as well as their insights
into methods of conservation and restoration of wood artifacts in Europe,
North America, and Asia provided a solid basis for the success of this under
taking. One of the goals during the examination of the literature was that not
only well-known conservators and scientists from countries that are leaders
in wood conservation should be represented, but that less well-known, often
not as readily accessible contributions should also be included. Only in this
manner was it possible to draw a comprehensive picture of the national and
international state of wood conservation. The Art and Archaeology Technical
Abstracts (AATA) of the Getty Institute were very helpful in our efforts to
evaluate as many publications as possible.
This book is not to be understood as a collection of recipes, although
there are many instances where techniques of conservation are described in
some detail. The use of conservation materials should take place only
when all other possibilities have been exhausted. Conservators/restorers must
understand very clearly that the preservation of an object by the application
of conservation materials and methods is accompanied by a loss of original
ity. Any treatment should be based on the premise "as little as possible, as
much as necessary?' Unfortunately, objective criteria and methods for deter
mining how much intervention is really necessary are rarely at hand. One
essential question is whether the original properties of the native wood of a
damaged object should be reestablished, or whether only a condition per
mitting safe presentation of the object is required. The number of cases where
former restorations are being removed again is increasing continually, and the
choice of conservation materials and methods must therefore be made espe
cially carefully and responsibly. There are all too many examples of cases
where the application, with the best of intentions, of conservation materials
VIII Preface
and methods resulted in a noticeable worsening of the condition of treated
objects with the passage of time. The inevitable, gradual deterioration of
objects should be slowed down and should not be accelerated by ill
considered conservation measures.
The authors proceed from the premise that nothing is perfect and that
everything is in need of continual improvement. They would therefore be
grateful for comments on the book that would eradicate errors, replenish the
missing, and rescue the forgotten from anonymity.
Many colleagues and associates have supported the development of this
book and have been of great help in its realization. We are especially indebted
to Professor Frank C. Beall, Professor W. Wayne Wilcox, Ms. Gail Getty,
Dr. Harald Berndt, Dr. Rod Eaton, Mr. Oskar Dietterle, Mr. Klaus Pelz and
Mr. Hans-Peter Wunderlich. Special thanks go to Mrs. Edith Boche for her con
tinual assistance and patience during the preparation of this book.
Last, not least, the authors would like to thank Mrs. Christiane Glier of
Springer-Verlag for her cooperation and helpful support.
Berlin, Berkeley and Eberswalde,
June 2001
A. Unger
A.P. Schniewind
W. Unger
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 History of Wood Conservation ..................... . 3
References ..................................... . 7
2 Wood Structure ................................. . 9
2.1 Macroscopic Structure ............................ . 9
2.1.1 Recent Wood ................................... . 9
2.1.2 Historical Wood ................................. . 10
2.2 Microscopic Structure ............................ . 11
2.2.1 Recent Wood ................................... . 11
2.2.2 Historical Wood ................................. . 14
2.3 Chemical Composition of Wood .................... . 15
2.3.1 Recent Wood ................................... . 15
2.3.1.1 Elementary Composition .......................... . 15
2.3.1.2 Chemical Components ............................ . 16
2.3.2 Historical Wood ................................. . 18
2.3.2.1 Elementary Composition .......................... . 18
2.3.2.2 Chemical Components ............................ . 19
2.4 Ultrastructure of the Cell Wall ..................... . 20
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3 Wood Properties ................................ . 23
3.1 Wood-Moisture Relations ......................... . 23
3.1.1 Recent Wood ................................... . 23
3.1.2 Historical Wood ................................. . 28
3.2 Density of Wood ................................ . 32
3.2.1 Recent Wood ................................... . 32
3.2.2 Historical Wood ................................. . 35
3.3 Strength and Stiffness Properties ................... . 37
3.3.1 Recent Wood ................................... . 37
3.3.2 Historical Wood ................................. . 38
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4 Corrosion Behavior of Wood ...................... . 43
4.1 Effect of Chemical Media ......................... . 43
X Contents
4.1.1 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.1.2 Acids and Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.1.3 Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.1.4 Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.1.5 Metals.......................................... 46
4.1.6 Corrosive Effects of Wood on Materials . . . . . . . . . . . . . . . 46
4.2 Weathering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5 Biological Deterioration of Wood . . . . . . . . . . . . . . . . . . . . 51
5.1 Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1.1 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1.2 Morphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1.3 Development and Reproduction . . . . . . . . . . . . . . . . . . . . . 53
5.1.4 Physiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1.5 Wood-Destroying Insects . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.1.5.1 Coleoptera (Beetles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.1.5.2 Isoptera (Termites) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.1.5.3 Siricidae (Wood Wasps) . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.1.6 Other Insect Pests of Wood . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.1.7 Enemies of Wood-Destroying Insects . . . . . . . . . . . . . . . . . 85
5.1.8 Monitoring of Insect Infestations . . . . . . . . . . . . . . . . . . . . 88
5.1.9 Attacks on Surface Decorations, Glues,
and Consolidants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.2 Fungi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.2.1 Taxonomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.2.2 Morphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5.2.3 Reproduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5.2.4 Physiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.2.5 Types of Damage to Wood . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.2.5.1 Wood Decomposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.2.5.2 Fungal Stain and Surface Molds . . . . . . . . . . . . . . . . . . . . . 105
5.2.6 Wood-Destroying Fungi . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.2.6.1 Basidiomycota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.2.6.2 Ascomycota and Deuteromycota . . . . . . . . . . . . . . . . . . . . . 121
5.2.7 Staining Fungi and Surface Molds . . . . . . . . . . . . . . . . . . . 122
5.2.7.1 Ascomycota and Deuteromycota . . . . . . . . . . . . . . . . . . . . . 122
5.2.8 Viability Tests of Fungi . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
5.2.8.1 Growth Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
5.2.8.2 Color Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
5.2.8.3 Determination of Adenosin Triphosphate (ATP) . . . . . . . . 128
5.2.8.4 Immunological Determination . . . . . . . . . . . . . . . . . . . . . . 129
5.2.8.5 Detection of Volatile Organic Compounds (VOC) . . . . . . . 129
5.2.9 Attack on Consolidants and Coatings for Wood . . . . . . . . . 129
5.2.10 Dangers to Health from Wood-Destroying Fungi........ 131
Contents XI
5.3 Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
5.3.1 Bacteria Destroying Pit Membranes . . . . . . . . . . . . . . . . . . 132
5.3.2 Bacteria Destroying Wood Cell Walls . . . . . . . . . . . . . . . . . 133
5.4 Marine Borers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
5.4.1 Teredinidae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
5.4.2 Limnoridae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6 Diagnosis of Wood Condition . . . . . . . . . . . . . . . . . . . . . . . 143
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
6.2 Mechanical Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
6.3 Electrical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
6.4 Optical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
6.5 Acoustic Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
6.6 Thermographic Methods........................... 152
6.7 Radiographic Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6.8 Nuclear Magnetic Methods . . . . . . . . . . . . . . . . . . . . . . . . . 157
6.9 Chemical and Biological Procedures . . . . . . . . . . . . . . . . . . 158
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
7 Liquid Wood Preservatives . . . . . . . . . . . . . . . . . . . . . . . . . 165
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
7.2 Inorganic Biocides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
7.2.1 Alkali Chlorides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
7.2.1.1 Sodium Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
7.2.2 Copper Compounds............................... 169
7.2.2.1 Copper(II) Sulfate and Other Copper Salts . . . . . . . . . . . . . 169
7.2.3 Mercury Compounds.............................. 171
7.2.3.1 Mercury(II) Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
7.2.4 Zinc Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
7.2.4.1 Zinc(II) Chloride and Other Zinc Salts . . . . . . . . . . . . . . . . 173
7.2.5 Arsenic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
7.2.5.1 Arsenic Trioxide and Arsenic Salts . . . . . . . . . . . . . . . . . . . 17 4
7.2.6 Fluorine Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
7.2.6.1 Sodium Fluoride and Other Fluorides . . . . . . . . . . . . . . . . 175
7.2.6.2 Fluorosilicates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
7.2.7 Boron Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
7.2.7.1 Boric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
7.2.7.2 Borax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
7.2.7.3 Polybor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
7.2.8 Chromium Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
7.2.8.1 Sodium Dichromate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
7.2.8.2 Potassium Dichromate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
7.2.8.3 Chromium(VI) Oxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
7.3 Organic Biocides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185