fleteOU IN THE CONSERVATION 1" OF WORKS OF GIULIA CANEVA, MARIA PIA NUGARI AND ORNELLA SALVADORI xx.. QUE r— E H co T O LI B BI 4v ICCROM BIBLIOTHEQUE o5 om +"--- e C —t- aps = AINHE111 BIOLOGY IN THE CONSERVATION OF WORKS OF ART Giulia Caneva, Maria Pia Nugari and Ornella Salvadori Rome 1991 ISBN 92-9077-101-1 © 1991 Giulia Caneva, Maria Pia Nugari, Ornella Salvadori and ICCROM - International Centre for the Study of the Preservation and the Restoration of Cultural Property Via di San Michele 13 1-00153, Rome RM, Italy 45 (5 Printed in Italy Sintesi Grafica s.r.l. Cover design: Studio PAGE, photo of detail of Trevi Fountain by Claudio Martini Drawings: Paolo Fuga Editing, computer layout: Cynthia Rockwell CONTENTS FOREWORD ix INTRODUCTION 1 Chapter 1 ENVIRONMENTAL FACTORS IN BIODETERIORATION 3 1.1 GENERAL PRINCIPLES OF ECOLOGY 3 1.1.1 Characteristics of ecosystems 3 1.1.2 The limiting factors 5 1.1.3 Growth and dynamism of populations and communities 8 1.2 PHYSICO-CHEMICAL LIMITING FACTORS 10 1.2.1 Edaphic factors 1.1Lit —p'.f..,,, 10 i., ,,,----,, ,„„;4,,,, 1.2.2 Water ,, , 10 r' 4- \ -, , 1.2.3 Atmospheric factors , .... ............. 12 1.2.4 Pollution effects k Chapter 1 REFERENCES 22 Chapter 2 MECHANISMS AND PHENOMENOLOGY OF BIODETERIORATION 25 2.1 PHYSICAL PROCESSES 26 2.2 CHEMICAL PROCESSES 27 2.2.1 Acidolysis 28 2.2.2 Complexolysis 28 2.2.3 Alkalinolysis 29 2.2.4 Exchange uptake of ions 29 2.2.5 Enzymatic degradation 30 2.2.6 Pigments 31 iii 2.3 AESTHETIC DAMAGE 31 2.4 PHENOMENOLOGY OF BIOLOGICAL ALTERATIONS 32 2.4.1 Relationships to the nature of materials, kinds of microorganisms and relative habitats 35 2.4.2 Relationship of physiology of organisms to environmental conditions 36 2.4.3 Perspectives in using the phenomenology of alteration as a bioindicator 37 Chapter 2 REFERENCES 39 Chapter 3 BIODETERIORATION OF ORGANIC MATERIALS 41 3.1 MATERIALS OF VEGETABLE ORIGIN 41 3.1.1 Chemical components and their susceptibility to biodeterioration 41 3.1.2 Wood 44 3.1.3 Paper 56 3.1.4 Textiles 60 3.2 MATERIALS OF ANIMAL ORIGIN 61 32.1 Chemical components and their susceptibility to biodeterioration 61 3.2.2 Parchment and leather 62 3.2.3 Textiles 64 3.3 COMPOSITE MATERIALS 65 3.3.1 Paintings 65 Chapter 3 REFERENCES 68 FIGURES 71 Chapter 4 BIODETERIORATION OF INORGANIC MATERIALS 87 4.1 STONE AND RELATED MATERIALS 87 4.1.a Bacteria and actinomycetes 88 4.1.b Fungi 92 4.1.c Cyanobacteria and algae 94 4.1.d Lichens 96 4.1.e Lower and higher plants 99 iv 4.1.f Animals 102 4.2 OTHER INORGANIC MATERIALS 103 4.2.1 Glass 103 4.2.2 Metals 104 Chapter 4 REFERENCES 107 Chapter 5 METHODS TO PREVENT BIODETERIORATION 113 5.1 GENERAL CONSIDERATIONS 113 5.2 INDOOR ENVIRONMENTS 113 5.3 OUTDOOR ENVIRONMENTS 118 Chapter 5 REFERENCES 120 Chapter 6 METHODS OF CONTROL 123 6.1 MECHANICAL METHODS 124 6.2 PHYSICAL METHODS 126 6.3 BIOLOGICAL METHODS 127 6.4 CHEMICAL METHODS 127 6.4.1 Pesticides and disinfectants: characteristics, qualifications and modes of application 127 6.4.2 Bactericides, fungicides, algicides 134 6.4.3 Insecticides 138 6.4.4 Biocides with both antimicrobial and insecticidal activity 140 6.4.5 Herbicides 141 6.5 BIOCHEMICAL METHODS 143 Chapter 6 REFERENCES 144 GLOSSARY 149 APPENDIX 154 1 ELEMENTS OF GENERAL BIOLOGY 154 1.1 Chemical composition of cells 154 1.2 Cellular organization 155 1.3 Chemical activity (metabolism) 156 2 ELEMENTS OF SYSTEMATICS OF BIODETERIOGENS 160 2.1 Kingdom Monera 160 2.1.1 Bacteria 160 2.1.2 Cyanobacteria 160 2.1.3 Actinomycetes 162 2.2 Kingdom Protista 162 2.3.1 Chlorophytes 162 2.3.2 Diatoms 162 2.3 Kingdom Fungi 164 2.4 Kingdom Plantae 166 2.4.1 Mosses and Liverworts 166 2.4.2 Higher plants 166 2.5 Kingdom Animalia 168 2.5.1 Insects 168 2.6 Symbiotic organisms 169 2.6.1 Lichens 169 3 TECHNIQUES OF ANALYSIS 171 3.1 Microbiological analyses 1 7 1 3.2 Botanical analyses 172 INDEX 173 vi ACKNOWLEDGMENTS We would like to thank the following colleagues who kindly assisted with photographic material for this book: Prof. A. Danin, Department of ESE, The Hebrew University, Jerusalem. Dr Fausta Gallo, Istituto per la Patologia del Libro, Rome. Drs A. Gambetta and S. Baldini, CNR Istituto per la Ricerca sul Legno, Florence. In addition, we are grateful to numerous colleagues at the Istituto Centrale del Restauro (ICR), who contributed ideas and support for the project. vii lo*dttlikorigo 0,7,0 , • . rifittli0,13Miatiiiftt biiiiisimjitudl roZt ft4 • FOREWORD Products and methods for the conservation of works of art must be chosen on the basis of careful diagnoses aimed at defining the intrinsic chemical and structural properties of their constituent materials and at understanding the reasons for the alterations that have been observed. The conservation of works of art and the performance of diagnostic studies in this field are, by definition, interdisciplinary activities that require the transfer of basic scientific knowledge from the restricted sphere of any single discipline to a larger number of persons involved in the same problems, but specialized in different areas. Among the disciplines forming what we can now rightfully call "Science for Conservation" is biology, due to the significant role played by biological factors in the deterioration of works of art. To know the most important biological agents and to understand the relationship of their physiology to environmental conditions is essential in order to adopt the most suitable methods to prevent and control biodeterioration without producing any negative interference with the constituent materials of the objects to be conserved. The present book fills the gap between theoretical treatises in the field of biology and the practical activities of conservation. It gives "non biologists" the basic infor- mation necessary for a serious approach to the problems of biodeterioration and, at the same time, it gives "biologists not specialized in this field" references and specific indications on the most important constituent materials and suitable treatments for them. Moreover, the extensive bibliographic references will allow readers to deepen their knowledge of various topics. Apart from the Appendix, with elements of general biology and systematics of biodeteriogens that are very useful in helping non-biologists to "break the ice" with the discipline, I appreciated very much the first chapter, in which biodeterioration is approached and set against the broader problem of interactions between each artifact and its environment. Those involved in practical conservation activities will also find chapters 5 and 6 of particular interest, as they describe and critically discuss the methods available at present to prevent and control biodeterioration. ix The book is the result of the authors' experiences, acquired in more than a decade of activity in scientific laboratories of the Italian Ministry of Cultural Property: the Laboratory for Biological Investigations of the Istituto Centrale per it Restauro, in Rome, for Giulia Caneva and Maria Pia Nugari, and that of the Soprintendenza ai Beni Storico-Artistici di Venezia for Ornella Salvadori. It is in just such a type of scientific laboratory, where scientists daily work closely with restorers and where they are asked to face together practical, urgent problems arising from conservation activities, that the richest study and research experiences can ripen, where a solid theoretical background must match a sense of practical organization. This combination makes it possible to meet the many special require- ments involved in conservation of artifacts that are frequently precious and unique. Marisa Laurenzi Tabasso INTRODUCTION This is a didactic text addressed to any person interested in the problem of biodeterioration of works of art. More precisely it was written for conservators without specialization in biology and for biologists lacking experience in the field of conservation. Given the vast scope of the subject, this volume aims to provide a general overview of the study of biodeterioration and conservation of constituent materials rather than a critical analysis or a discussion of specialized literature. The term `biodeterioration' refers to any undesired change in material properties due to the activity of microorganisms and/or organisms belonging to various systematic groups. The biological aspects of conservation of works of art can be approached in different ways. First, the negative effects of biological populations, e.g., biodeterioration of materials, must be evaluated for prevention and control. Second, the potential positive contribution of biological populations to diagnosis and conservation treatments must be considered. The processes of biodeterioration will be analyzed. Doing so will provide the basic information for understanding how a biological population can be used to evaluate weathering capacity and to interpret environmental parameters. Microorganisms and organisms normally play an important role in the mechanisms of weathering of organic and inorganic materials. In fact, they can cause not only aesthetically undesirable effects, but overall, a progressive loss of cohesion and the transformation of component materials. Biological alterations differ according to ecological peculiarities such as the substrate, the kind of microorganisms and organisms involved and the characteristics of the environment where the object is located (micro- and macro-environment, atmospheric pollution, etc.). Environmental parameters and the nature of the substrate both drastically influence the potential attack by biological populations in relation to the presence of favoring or limiting factors and to their metabolic characteristics. These factors will be analyzed before describing the mechanisms and the phenomenology of biodeterioration. Moreover, the biodeterioration of materials in nature cannot be considered as an isolated phenomenon; in fact, it always occurs together with other physical, chemical or physico-chemical deterioration processes, with which it is strictly correlated.