The Science of Paintings W. STANLEY TAFT, JR. JAMES W. MAYER Springer THE SCIENCE OF PAINTINGS THE SCIENCE OF PAINTINGS W. S TANLEY TAFT, JR. JAMES W. M AYER With Contributions from: PETER IAN KUNIHOLM RICHARD NEWMAN DUSAN C. STULIK With 166 Illustrations, 28 in full color W. Stanley Taft, Jr. James W. Mayer Department of Art Center for Solid State Science Cornell University Arizona State University 224 Tjaden Hall P.O. Box 871704 Ithaca, NY 14853 Tempe, AZ 85287 USA USA [email protected] [email protected] Contributors Peter Ian Kuniholm Richard Newman Dusan C. Stulik Department of Art History Museum of Fine Arts, The Getty Conservation Cornell University Boston Institute Library of Congress Cataloging-in-Publication Data Taft, W. Stanley. The science of paintings / Stanley Taft, James W. Mayer ; with contributions by Peter Kuniholm, Richard Newman, and Dusan Stulik. p. cm. Includes bibliographical references and index. ISBN 0-387-98722-3 (hardcover : alk. paper) 1. Painting—Appreciation. I. Mayer, James W., 1930– . II. Newman, Richard, 1951– . III. Stulik, Dusan, 1956– . IV. Kuniholm, Peter. V. Title. ND 1143.T34 2000 751—dc21 99-39642 Printed on acid-free paper. © 2000 Springer-Verlag New York, Inc. All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer-Verlag New York, Inc., 175 Fifth Avenue, New York, NY 10010, USA), except for brief excerpts in connection with reviews or schol- arly analysis. Use in connection with any form of information storage and retrieval, elec- tronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Production managed by MaryAnn Brickner; manufacturing supervised by Joe Quatela. Typeset by Matrix Publishing Services, Inc., York, PA. Printed and bound by Maple-Vail Book Manufacturing Group, York, PA. Printed in the United States of America. 9 8 7 6 5 4 3 2 1 ISBN 0-387-98722-3 Springer-Verlag New York Berlin Heidelberg SPIN 10707620 PREFACE The beauty, mystery, joy, and inspired observation of the human spirit that paintings evoke result from a complex of intuitive and cognitive choices made by the artist. An understanding of the genesis of these choices can be as elusive as the resulting imagery, but great paintings seem to initiate in us a curiosity about the ideas, methods, and materi- als used by their creators. In the twentieth century connoisseurship has been enriched by the application of methods of scientific analysis. The results of these investigations into the physical properties of paintings have shed new light on their authenticity and individual histories as well as on the craft in general. Developments in the fields of physics and chemistry have allowed us to understand still more about how we per- ceive and interact with paintings. This book is intended for those both inside and outside the field of art who wish to gain insight into the making of paintings. It is directed toward students, teachers, and scientists in engineering, physics, and chemistry as well as those in art, art history, and art conservation. This book grew out of the interdisciplinary undergraduate-level course Art, Isotopes, and Analy- sis taught at Cornell University by the two authors and supported in lec- tures and seminars by three of the contributing authors: Dr. Richard Newman, of the Museum of Fine Arts, Boston; Dr. Dusan Stulik, of the Getty Conservation Institute; and Prof. Peter Kuniholm, of Cornell Uni- versity. Students enrolled in the course represented a broad range of ma- jors and expertise in both art and science (they were not expected to have taken college-level math, physics, or chemistry). The course gave inspira- tion and structure to the book, which developed from a student text com- piled by the authors and other contributors to the course. Much of the information in the Technical Appendices is derived from these lecture notes. v vi PREFACE The book is divided into two sections: (1) nine chapters describing the structure of paintings, the differences in painting media, and the physical properties of painting materials. The nature of light and color and their interaction lead to a view beyond the eye, enhanced by x-radiation, infrared radiation, and nuclear radiation, enabling a deeper penetration into the painting. Analysis of pigments, binders, and support materials as well as the application of dating techniques is also described; (2) a list of references and technical appendices that provide, in detail, the physics and chemistry applicable to the topics covered in the main text. The problem sets and exams used at Cornell University for the Art, Isotopes, and Analysis course, as well as a solution set, are available through the publisher, Springer-Verlag. The authors acknowledge the help and support of our Cornell Uni- versity colleagues. Professor Donald D. Eddy, of the Department of Eng- lish, has for many years taught The History of the Book, a course that was the inspiration for Art, Isotopes, and Analysis. Eddy also partici- pated in the organization of Art, Isotopes, and Analysis and presented lectures on printing, binding, paper, and the history of books. Professor Peter I. Kuniholm, of the Department of the History of Art and Archeaol- ogy and director of the Aegean Dendrochronology Project, provided lec- tures and data on dendrochronology. Professor David D. Clark and Howard C. Aderhold, of the Department of Nuclear Science and Engi- neering, and Professor Albert Silverman, from the Department of Physics and Nuclear Science, gave support in the areas of physics and neutron- induced autoradiography. Peter Revesz provided proton-induced x-ray emission (PIXE) analysis of pigments. Debora Mayer, a private art con- servator in Bedford, New Hampshire, and formerly at the Winterthur Museum, gave lectures on beta-radiography of works of art on paper and on paper fibers. We are indebted to the students at Cornell who attended our course and those who served as our undergraduate teaching assis- tants. These teaching assistants attended the course, carried out research projects, and participated as graders, advisors, and assistants. This book is being used at Cornell University as a text in studio paint- ing courses and at Arizona State University as a supplemental text in the course Patterns in Nature, which is intended for teachers of grades K–12. CONTENTS Preface v 1. THE STRUCTURE AND ANALYSIS OF PAINTINGS 1 1.0 Introduction 1 1.1 What Is a Painting? 2 1.2 Choices 6 1.3 Examination and Analysis 8 2. PAINT 12 Dusan Stulik, the Getty Conservation Institute 2.0 Paint 12 2.1 Pigment 15 2.2 Fresco 16 2.3 Tempera 19 2.4 Encaustic 22 2.5 Oil 23 2.6 Acrylic 24 vii viii CONTENTS 3. ORGANIC BINDERS 26 Richard Newman, Museum of Fine Arts, Boston 3.0 Introduction 26 3.1 Carbohydrate-Containing Binders 29 3.1.1 Honey 29 3.1.2 Plant Gums 29 3.2 Protein-Containing Materials 31 3.2.1 Animal Glue 32 3.2.2 Egg White and Egg Yolk 33 3.2.3 Casein 35 3.3 Oils 36 3.4 Waxes 38 3.5 Natural Resins 40 4. THE PAINTER’S COLOR AND LIGHT 42 4.0 Color, Light, and Space 42 4.1 Color Characteristics 44 4.2 Afterimages 45 4.3 Simultaneous Contrast 46 5. COLOR AND LIGHT 50 5.0 Introduction 50 5.1 Light: Photons and Waves 51 5.2 The Color of Objects 56 5.3 Color: Illumination and Metamerism 60 5.4 Additive Color 61 5.5 Subtractive Color 63 5.6 The Eye and Color Sensation 63 Contents ix 6. OPTICS OF PAINT FILMS 66 6.0 Introduction 66 6.1 Reflection 66 6.2 Refraction 69 6.3 Scattering of Light 72 6.4 Absorption of Light 73 6.5 Fluorescence 75 7. BEYOND THE EYE 76 7.0 Introduction 76 7.1 Pigment Response in the Infrared 76 7.2 Pigment Response to X-Rays: Absorption 79 7.3 Pigment Response to X-Rays: Emission 81 7.4 Pigment Response to Neutrons 82 7.5 Overview 85 8. DETECTION OF FAKES 86 8.0 Introduction 86 8.1 A Successful Forger 87 8.2 Visual Examination 90 8.3 Dating and Pigment Identification 91 8.4 Sampling 93 8.5 Fake/No Fake 93 9. OBJECT OF INTERACTION 95 9.0 Beyond Analysis 95 x CONTENTS APPENDICES 101 A. Photons, Electrons, and the Photoelectric Effect 103 B. Refraction, Reflection, and Dispersion 107 B.1 Index of Refraction 107 B.2 Reflection and Scattering 110 B.3 Dispersion 113 B.4 Varnishes and Refraction 115 B.5 Hiding Power 116 C. Photon Absorption: Visible, Infrared, and X-rays 118 C.1 Mechanism for the Absorption of Light 119 C.2 Infrared Reflectography and Hiding Thickness 125 D. The Chromaticity Diagram 128 E. Periodic Table and Crystal Structure 131 E.1 Electrons, Nuclei, Isotopes and Atomic Number 131 E.2 Periodic Table 133 E.3 Structure of Pigment Crystallites 135 E.4 X-Ray Crystallography 138 F. Electron Energy Levels and X-Ray Emission 141 F.1 Yellows and Pigment Anachronisms 141 F.2 Electron Shells 142 F.3 Electron Binding Energies 145 F.4 X-Ray Emission 147 F.5 X-Ray-, Electron-, and Proton-Induced X-Ray Emission 149 G. Nuclear Reactions and Autoradiography 156 G.1 Nuclear Reactions 156 G.2 Radioactive Decay and Decay Law 158 G.3 Counting Statistics 162 G.4 Neutron Activation Analysis and Autoradiography 163 H.