TERRY T. SCHAEFFER, EFFECT OF LIGHT ON MATERIALS IN COLLECTIONS: DATA ON PHOTOFLASH AND RELATED SOURCES. Los Angeles: Getty Conservation Institute, 2001. 211 pages, softcover, $30. Available from Getty Trust Publications, 1200 Getty Center Drive, Ste. 500, Los Angeles, Calif. 90049-1682. ISBN 0-89236-645-1.
Museum authorities have long questioned the possibility of photochemical damage to materials in their collections owing to the use of flash lamps during photography. To date, no more than a few direct studies of the effects of photoflash have been carried out. As part of a formal decision to look into this matter in greater depth than in the past, the Getty Conservation Institute commissioned Terry T. Schaeffer to undertake a search of the technical and conservation literature in an effort to locate information that would help in addressing this question. This report is the result of that literature search. Along with other contributions, a record is now available of persons and laboratories worldwide that have been engaged in research on the effects of exposure to visible and near-ultraviolet radiation on more than 50 materials with which conservators may be concerned.
The 168-page text contains an introduction, four chapters, and an extensive bibliography. Chapter 1, about 30 pages of “Background Information,” provides concise overviews of the topics of photochemistry, radiometric terms, filters, and light sources. The 90-page chapter 2 presents the “Results of the Literature Search,” virtually an annotated bibliography covering photochemical studies on pigments, dyes, natural fibers, pulp and paper, ink, and natural and synthetic resins. To assist those who may not be interested in the full technical information, Schaeffer has set off in italics about 97 short summary statements throughout the chapter, each bearing the label “Conservator's Note.”The 30-page chapter 3,“Technical Details,” presents the calculations on about 60 research findings that permitted reasonable estimates to be made with respect to the number of flash exposures that might just begin to result in a perceptible change in a property such as color, brittleness, or cross-linking. The text closes with 10-page chapter 4, entitled “Discussion,”of which more will be said below.
Writing on technical matters for the conservation field regularly poses a problem. The information is of interest to museum personnel likely to possess a wide variety of backgrounds and training. To whom, then, shall authors address their remarks? The Getty Conservation Institute has taken a significant step to ameliorate the situation by establishing two series of books, one designated as “Tools for the Conservator,” the other “Research in Conservation.” The latter series, of which Schaeffer's book is the seventh, is dedicated to providing authoritative information on such technical subjects as the biodeterioration of stone, the use of inert gases in the control of insect pests, and the properties of oxygen-free cases. The focus is toward the technically oriented person who must advise museums in regard to such matters and toward the professional who is likely to undertake further research.
Schaeffer's objective was to find sufficient information in the previously published research and conservation literature that would permit estimates to be made as to the amount of flash or studio photography that would represent 1% of the exposure necessary to produce a just detectable or just acceptable change in the chemical or physical properties of a particular material. For example, if the unwanted change is with respect to color, then the objective would be to estimate the exposure to flash that would cause a color difference of no more than 1% of a CIE L*a*b*Δ E of 1, the difference of 1 being generally regarded as a just perceptible change in color. Admittedly, this is a high standard to have set.
The number of publications in the scientific literature dealing with the subject of photochemistry tends to be overwhelming. Fortunately, the present task was narrowed considerably by the restriction to limit the search to studies that involved wavelengths no lower than 360 nm, those able to pass through ordinary glass and therefore likely to be encountered in the museum environment. Even so, a bibliography of 392 references resulted. Many more references, of course, had to be read by the author in order to eliminate studies that involved shorter wavelengths.
The text gives extensive examples of how the minimum permissible number of flash exposures was estimated from the reported results of fading and chemical changes arising from exposure to a variety of light sources. For example, the radiant power of a flash, in watts per square centimeter of visible and near-ultraviolet radiation that would fall upon an object in a flash of .01 second, was divided into the total watt-seconds per square centimeter calculated to result in a color change of 1% delta E. The latter often had to be converted from the number of foot-candle hours of a specified light source that had been found to cause a color change of much larger delta E, for example, 14. The reciprocity principle was generally assumed to hold true, so that the footcandle hours were reduced by 0.01/14 to estimate the proposed minimum exposure, 1% of a delta E of 1. Other assumptions had to be made. Thus, to estimate the intensity of the illumination, a reasonable distance had to be specified between the object being photographed and the light source. The presence or absence of ultraviolet above 360 nm must also be considered.
In chapter 4, six paragraphs are devoted to the above “Assumptions Used for the Calculations.” A section entitled “Assessing Risk” follows. The latter reviews questions that the staff will need to consider to estimate the potential for harm that might be incurred when a particular item is photographed. What is the ultraviolet content of the flash or studio lighting in relation to the source of illumination used during exhibition? How popular with the public is a particular item likely to be? Is the deterioration of a specific material known not to follow the reciprocity principle? Would it be advisable to use a stand-in while setting up equipment for studio photography? In the case of especially sensitive materials, Schaeffer recommends that a record be kept of all exposures to light.
An initial inquiry usually raises more questions than answered; this project is no exception. Chapter 4 closes with four pages of “Suggestions for Further Action” in which about 20 supplementary research projects are proposed. Several deserve particular mention. For example, conservators regularly level criticism at scientists, pointing out that they usually conduct their research on samples that are freshly prepared, whereas the conservator is called upon to treat materials that have already undergone a certain degree of aging. Might not the aged materials behave differently? Experiments to explore this possibility should be easy enough to design. Some relevant information already exists with respect to fading and to prior exposure of paper to heat and light. We should begin to settle this question when new projects are undertaken. On another matter, tendering, the role of certain dyes in giving rise to the photo-induced embrittlement of textiles, has been extensively studied by textile and dye chemists; a review of this subject would seem in order. An ongoing search should also be made for examples of photochemical processes that do not follow the reciprocity principle and for degradation processes that tend to speed up in time. In the immediate future, additional direct experimental measurements of the effects of photoflash and reprographic light sources must be undertaken; after all, it was the desire for this information that initially led to Schaeffer's report.
The need for a simple light-exposure monitor is expressed. A number of colleagues have published preliminary efforts to develop a pigment or dye that would conveniently change color on the wall of a room or showcase, in effect integrating the exposure over time. Instruments are also available today that can serve this purpose. Schaeffer suggests nonetheless that additional attention be given to the ISO R105 Blue Wool fading standards, British Standard 1006 (1990). The Blue Wools are of moderate cost, well recognized, and convenient to use. Many of the cited publications used the Blue Wools as a measure of the lightfastness of a particular pigment or dye. In recent years, David Saunders at the National Gallery, London, has been investigating several aspects of their behavior.
Schaeffer points out that determination of the lightfastness of specific artifacts may be considerably simplified in the future. Scarcely visible fading measurements can now be carried out directly on a very small area using equipment developed by Paul Whitmore at Carnegie Mellon University (JAIC 41 : 395–409). Spectral reflectance data can also be obtained nondestructively with this same equipment as well as with the fiberoptic probe recently described by Marco Leona and John Winter (Studies in Conservation 46 : 153–62).
It is a bit disconcerting not to find a section in the report labeled “Summary and Conclusion.” Nonetheless, they are there. The opening six paragraphs of chapter 4 sum up things very well. At the beginning of the chapter, a chart summarizes Schaeffer's findings regarding the range of sensitivity to photoflash in eight categories of material: thermoplastic resins, paper, wood, silk and wool, photographic and reprographic materials, and colorants. The horizontal axis is marked off in decade steps, powers of 10, extending from 101 to more than 100 million flashes, 108. Within each of the categories of material, the range of the number of flashes estimated to be minimally permissible is set off in brackets. Schaeffer has designated the two most sensitive situations as “restrict exposure” (most sensitive) and “use caution” (next most sensitive). For the two, the number of flashes that can be tolerated extends from 10 to 10,000 (101 to 104). What types of artifact are to be so classified? Reference to the ISO Blue Wools may help. On page 144 mention is made of a series of dyes that fade at a rate equivalent to Blue Wool no. 1, for which it is stated that no more than 10,000 (104) flashes would result in 1% of a just perceptible fade. It seems fair to say, then, that the materials falling in these two highly sensitive classifications are those whose sensitivity toward light is equivalent to Blue Wool Standard no. 1 or less. This is essentially stated on page 32. Fading at a rate about 100 times slower, Blue Wool no. 6, well known for its reasonable stability, would be placed at the step marked 106. Schaeffer designates the situations in the chart above 104 “probably permissible,” extending at least to 100 million flashes, 108. One may ask what sort of organic matter would be affected by light at a rate millions of times slower than Blue Wool no. 1? Materials estimated to be this highly resistant to photochemical degradation perhaps would have their long-term stability dependent more upon microbiological or thermal effects than upon light.
In the course of this assignment, Schaeffer found about 60 research studies in which there was sufficient information to permit reasonable estimates to be made of the number of flashes that would represent 1% of the exposure necessary to produce a noticeable or unwanted change in properties in a variety of materials. Of the 60, nearly a quarter involved materials estimated to deserve restriction, or at least notable caution, in the use of studio as well as flash photography. These materials apparently are those whose sensitivity to light is equivalent to ISO Blue Wool no. 1 or less. Earlier considerations of this matter had sometimes reached the conclusion that there was generally little to worry about concerning exposure to flash. However, the permissible change in properties was often set higher than Schaeffer's standard. As well, the accumulative effect of exposures over many decades may not have been fully considered. In only 50 years, for example, a modest 20 hand-held flash shots a week would result in more than 50,000 flashes or, as Schaeffer expresses her numbers, 5x104 flashes.
The conclusion in 25 words or less: Consideration of the literature indicates that materials known to be highly sensitive to photochemical damage warrant restriction in the use of flash photography. Mission accomplished. Next order of business: additional direct experimental measurements.
- Robert L. Feller
- 220 N. Dithridge St.
- Pittsburgh, Pa. 15213
ROSAMOND D. HARLEY, ARTISTS' PIGMENTS, c. 1600–1835. London: Archetype Publications Ltd., 2d ed., rev., 2001. 246 pages, soft-cover, $45. Available from Archetype Publications, 6 Fitzroy Square, London W1T 5HJ, or from Cotsen Institute of Archaeology at UCLA, A210 Fowler Building, Box 951510, Los Angeles, Calif. 90095. ISBN 1-873132-91-3.
This book was originally published in 1970 and had been out of print for six years when the second, revised edition appeared in 1982. That edition is in turn out of print, and it is here reprinted, unaltered except for the addition of a new appendix.
With the first appearance of this volume, Rosa-mond Harley made a valuable contribution to the history of pigments as shown by historical documentation, and the volume's reappearance is welcome. The research represented here concentrates on English primary documentary sources from the 17th to the mid-19th century, with some reference to other literature regarding pigments and painting in Europe. This book joined the ranks of pioneering earlier works on the history of artist's colors, such as those by Charles Eastlake and Mrs. Merrifield and later such authors as D. V. Thompson and, more recently, Leslie Carlyle, to name a few.
Chapters 1 and 2 discuss the manuscripts and printed books from the period. Until the mid-17th century, manuscripts were the chief source of information; after that, printed books became more common. The author points out that the literary sources contain few details of manufacture. Rather their value is their commentary on pigments used, their preparation as artist's colors, and the purpose for which they were best suited. She notes that it is important to distinguish, whenever possible, between sources passing on earlier information and those describing contemporary practice. Importantly, the reliability of these sources is indicated.
Chapter 3 deals with relevant public records, which are sources of history for the color trade that, until Harley's work, had not been studied with reference to pigments. These sources are therefore described in detail. They include customs records and patents for inventions. Also consulted were records from the chartered trading companies, the Levant Company and the East India Company; the former were not useful but the latter provided some information. Documentary resources from the Royal Society (founded 1662) were determined to be useful up to 1700. The Royal Society of Arts (founded 1754) revived interest in the manufacturing processes, as indicated by its very descriptive early name, the Society for the Encouragement of Arts, Manufactures and Commerce. The aims of the society, according to chemist Robert Dossie in 1758, were to furnish “means of establishing and improving useful arts.” By the beginning of the 19th century, scientists were publishing details of their research in journals, which had now begun to appear. Other resources were manuscript records and early printed catalogs of artist's colormen such as Winsor & Newton Ltd.
The heart of the book is presented in chapters 4–12. Here individual pigments are discussed, broadly grouped by color, with inorganic and organic colorants being dealt with separately in some categories. These chapters are clearly presented, truly a mine of information on all aspects of the history, use, and properties of pigments.
The final chapter, Chapter 13, entitled “Science and Art,” points out how closely connected this history is with the development of technology and chemistry. It includes useful summaries of the changing use of various colors and the reasons behind these changes. Comparing remarks in scientific papers with information provided by colormen is instructive. Harley notes the interesting point that a pigment regarded as satisfactory by a chemist, when produced in small amounts, might be often unsatisfactory when manufactured on a large scale.
Appendix 1 lists abbreviations used, including those for Public Record Office references. Appendix 2, “Books with Named Colour Samples,” lists the books that contain actual color samples and mentions unusual or interesting colors therein. In appendix 3, “Patents for Colour-Making in the Early Seven-teenth Century,” the author notes that there was increased industrial activity in England during this period and describes the mechanism of patent granting. New in this edition is appendix 4, “Some New Water Colours in the Nineteenth Century,” which appeared as an article in The Conservator in 1987; it supplies information on iodine scarlet and cadmium yellow, which were only briefly mentioned in the 1982 edition.
This book serves a wide audience: the conservator and the conservation scientist, the artist and the art historian, and the historian of technology. Works like this are important and excellent adjuncts to laboratory identifications of pigments. These two types of research—documentary and scientific—complement each other. This reviewer has found Dr. Harley's book a dependable source of information on a number of occasions, particularly in the course of research during editing or preparing chapters for the series on artist's pigments published by the National Gallery of Art. Even in the field of Asian pigments, pertinent facts are found here, as when the author notes that a good quality of orpiment from China was available in England in the 19th century and known as “Chinese yellow.”
It would have been wonderful to have a completely revised version of this book. However, it would not have been fair to the author, who has now retired, to suggest that she undertake this task. Fortunately what we do have here is a fully documented summary of our knowledge, as of 1982, of the subject of pigments in England from the 16th to the mid-19th century, and, as the author herself remarks, the book provides a basis on which the researcher can depend before pursuing the publications and other resources of the past 20 years.
The first edition of this book was a slightly altered version of Rosamond Harley's Ph.D. thesis awarded in 1967 by the Courtauld Institute of the University of London. She worked in the artist's color industry, at Winsor & Newton Ltd., from 1958 to 1973, and then for two years was chief of scientific documentation at the Canadian Conservation Institute. The balance of her career since 1975 was as senior lecturer in conservation at Gateshead Technical College, where in more recent years she was also in charge of the M.A. degree course in conservation of the fine arts.
Finally I cannot end this review without a tribute to Archetype Publications. It produces significant original publications such as the recent The Art of All Colours: Medieval Recipe Books for Painters and Illuminators by Mark Clarke and reprints important classics like this one. This volume is just one of many examples of this publisher's contributions to our field, for which we should all be grateful.
- Elisabeth West FitzHugh
- Research Associate
- Department of Conservation and Scientific Research
- Freer and Sackler Galleries
- Smithsonian Institution
- Washington, D.C. 20560
BARBARA WILLS, ED., LEATHER WET AND DRY: CURRENT TREATMENTS IN THE CONSERVATION OF WATERLOGGED AND DESICCATED ARCHAEOLOGICAL LEATHER. London: Archetype Publications Ltd., 2001. 77 pages, softcover, $25. Available from Archetype Publications, 6 Fitzroy Square, London W1T 5HJ, or Cotsen Institute of Archaeology at UCLA, A210 Fowler Building, Box 951510, Los Angeles, Calif. 90095. ISBN 1-873132-77-8.
Leather Wet and Dry is the proceedings of a joint meeting of the United Kingdom Institute for Conservation (UKIC) Archaeological Leather Group and the Department of Conservation at the British Museum (BM) held March 23, 1998. Edited by Barbara Wills, chair of the Archaeological Leather Group and a senior conservator in the Organic Artefacts Section of the BM, it collects some information about conservation approaches to leather objects excavated from two extreme environments where organic preservation is more common—waterlogged and desiccated.
The conference was held to pull together information about conservation of leather from both waterlogged and desiccated environments. As noted in the preface, treatments for waterlogged leather often come under the rubric of other waterlogged organic materials. Treatments for desiccated leather are much less published and, as reflected in the articles, much less standardized. This situation reflects to some extent the current international development of archaeological conservation, in which there is a longer history of conservation and support by governmental institutions in northern climes where waterlogged material is more commonly found. In contrast, in many arid areas of the world where desiccated leather is more likely to be excavated (often by foreign expeditions), internal institutional support is limited and conservation is carried out in short-term programs that may accompany the excavation. All the authors in this volume did their conservation training in northern Europe and now work in northern Europe, though they may work outside this area on sponsored projects. Five of the papers discuss water-logged leather from northern Europe, two papers discuss conservation of desiccated leather using examples from the Middle East, and the final paper describes experimental work on buried leather in England.
The papers on waterlogged leather reflect its longer history of treatment at a number of venues and showcase a number of approaches to preservation, both active and passive, that have been used over the years. Kirsten Suenson-Taylor's paper summarizes work at the Museum of London to evaluate the effectiveness of a glycerol pretreatment–freeze-drying method used for more than 20 years. This work has been previously published in detail in several articles that are individually summarized in this paper. Including it in this volume simply ensures that readers new to the literature will be aware of that previous work. Elizabeth Peacock reviews the fashions in conservation treatment of medieval waterlogged leather used at Vitenskapsmuseum in Trondheim, Norway, and describes experimental work done on leather previously treated with a variety of lanolin-based impregnants and dressings. The research resulted in a bulk retreatment of these objects with extraction using Genklene followed by impregnation with a 10% polyethylene glycol to 10% glycerol volume to volume in water combination (10%/10% PEG/glycerol). Based on this experience, the treatment for newly recovered leather was reevaluated and is now also based on a PEG-glycerol mixture followed by freeze-drying. An important aspect of this paper is not just its focus on the laboratory treatments but its discussion of the ramifications of field treatment methods and long-term storage. Iva Hovmand and Jennifer Jones describe experimental evaluation of a common pretreatment technique for waterlogged leather using disodium ethylene diamine tetraacetic acid (2NaEDTA) to remove metal ions (especially iron) deposited in leather during burial. They used energy dispersive x-ray fluorescence (EDXRF) analysis to evaluate the mineral content of the leather and found that 2NaEDTA did remove some of the elements analyzed for. However, some of the minerals still remain in the leather and may cause deterioration in the long term. They also found that the shrinkage temperature of the leather dropped, though not below normal storage temperatures. Marquita Volken's paper summarizes the “pragmatic” approach used by the State Service for Archaeological Investigation in the Netherlands. The weakest paper in the volume, it celebrates an approach to treatment based on the human senses and experience. The technique used for waterlogged wood is slow air-drying and impregnation in 60% PEG 600. Although the evaluation techniques are not stated, the author reports that leather treated up to 30 years ago is still stable except for a little lightening of color. The author also gives a number of brief descriptions of treatments she has tried on dry leather with variable success. The final paper on waterlogged leather by Veroniqué Montembault reviews the treatments commonly used in France since the late 1970s and reports on more recent work by the Centre de Recherche sur la Conservation des Documents Graphiques to evaluate waterlogged leather treatments. The treatment currently used for waterlogged leather is impregnation with 33% PEG 400 followed by freeze-drying.
Two articles deal specifically with desiccated leather, though two others in the volume treat it in a cursory way. Barbara Wills reviews the challenges of conserving desiccated leather using examples from excavation in Sudan and in the laboratory at the British Museum. She describes experience with two broad categories of ancient dry leather: well preserved material from very dry environments, and very deteriorated material from sites that may have been occasionally wet. A real strength of this paper is its argument for a conservator's analysis of the leather to uncover information about technologies and contribute to the understanding of broader archaeo-logical questions. She also reviews experience with on-site treatment and consolidation of dry leather with an available polyvinyl butyral (PVB), Mowital B30H. A case study by Pippa Cruickshank describes the recovery and conservation of desiccated leather shrouds from the Jordan valley. Her honest review of the pros and cons of the success she had with the consolidants and methods used serve as good guidance for others going to work in similar environments. The limitations of the treatments and materials used in both these papers illustrate the need for research into effective consolidation and support techniques for desiccated leather that take place outside the constraints of fieldwork.
The last paper, by Glynis Edwards, gives an overview of two earthwork projects constructed in the 1960s to evaluate the deterioration of buried materials over time. She describes the leather that was buried at Overton Down and Wareham and gives information on where the publication of this work can be found. This paper, like the first paper in the volume, simply leads readers unfamiliar with the literature and history of archaeological leather conservation to research published elsewhere.
This book is a good overview of the recent history of conservation where many techniques were first based on craft or experience and then moved toward analytical techniques to better understand what is happening either at a microscopie or chemical level for individual objects, or over time to collections. As with most published proceedings, it is uneven, based on the experience and knowledge of each author. It will be most useful to individuals who are just beginning to work with archaeological leather who need to gain familiarity with past work. It is interesting to see how different techniques were popular in different countries.
Most techniques in archaeological conservation are developed in reaction to a need at the time a material is excavated. This happened with water-logged leather, and it is only now, with older collections, that there is a review of the effectiveness of these techniques. For desiccated leather, it appears we are still at the reactive stage. By collecting papers on both waterlogged and desiccated leather, this book provides an opportunity to review the development of the field for one material in one area of the world. The UKIC Archaeological Leather Group, the British Museum, and Barbara Wills are to be commended for collecting this information from a number of northern European institutions and individuals. From her foreword, it is clear that Wills understood the “heterogeneous” and “individual” nature of these papers. It would be interesting to see a similar review by researchers from the Western Hemisphere: we would likely find the same pattern of information with lots of work on waterlogged leather and more sporadic attempts to preserve desiccated leather. By focusing on a single material, leather, this book clearly illustrates how conservation has evolved through fashions and by simply reacting to an immediate need. As with many other materials and treatments, now that we have more time and resources, we need to reexamine whether our earlier decisions were right.
- Jessica S. Johnson
- Senior Objects Conservator
- National Museum of the American Indian
- Smithsonian Institution
- Cultural Resources Center
- 4220 Silver Hill Rd.
- Suitland, Md. 20746-2863
ACHIM UNGER, WIBKE UNGER, AND ARNO P. SCHNIEWIND. CONSERVATION OF WOOD ARTIFACTS. Berlin, Germany: Springer-Verlag, 2001. 578 pages, hardcover, DM 372.00. Available from Springer-Verglag Heidelberg, www.springer.de. ISBN: 3-540-41580-7.
The profession is well served by the recent release of this multiauthored publication on the conservation of wood objects from “before the Christian era to the year 2000” (p. vii). The authors' stated purpose is to present a “comprehensive source on the history of wood conservation” (p. 1) and to “systematically organize the extant literature on the conservation of cultural property made of wood” (p. vii). The book is a comprehensive publication of essential information on the nature of wood, how it can degrade, and how it can be preserved. The intended audience includes conservators and wood-conservation scientists. The work represents research performed and collected by the three authors from the Rathgen-Forschungslabor, Staatliche Museen zu Berlin, Germany; the University of Applied Sciences, Eberswalde, Germany; and the Forest Products Laboratory, University of California at Berkeley.
This publication is written in textbook fashion using a numerical system for organization. It is not intended to present new research, but rather to pull together existing work into one source, which is the book's clear strength. While readers may not necessarily find new information here, they will find material in one reference that heretofore would have been laboriously collected from a variety of publications. This is a book about wood rather than the objects made from it, as there is little discussion about the joinery, finish, veneer, or paint used to create cultural property. The writers have understandably focused on classifications of wooden cultural property that are most at risk of deterioration. The text is weighted heavily toward architectural, archaeological, and outdoor materials, with less commentary relating directly to interior furniture and the decorative arts.
The authors write about the history of wood conservation, wood deterioration, diagnosis, preservatives, preventive work, consolidants, adhesives, and gap fillers. The authors are not concerned so much with how to conserve wood artifacts as with presenting information to assist the conservator and scientist in diagnosis, problem solving, and decision making.
The nature of wood is sufficiently covered in the first four chapters. The authors have correctly chosen to establish a clear understanding of the material before delving into degradation, assessment, and conservation. Chapter 5 covers the biological deterioration of wood with an in-depth review of insects, fungi, bacteria, and marine borers as they relate to wood degradation. Examples of conservation projects are referenced in this section, which helps to put the particulars into context. The biological deterioration section and the following chapter on the diagnosis of wood conditions are sensibly placed before the conservation materials and techniques portion of the book. The diagnostic systems are those the authors found to be helpful in assessing the state of decay in wood. There is an extremely useful table that covers the methods, procedures, properties tested, preferred applications, and advantages and disadvantages of inspection methods for wood (table 6.1, pp. 145–47).
The materials, procedures, and techniques section of the book, which is carefully distributed in chapters 7 through 11, contains clear descriptions, chemical terms, formulas, and procedures relating to wood conservation. The history of use of each substance or system and its potential impact on woods of various conditions or age are reviewed. It is quite extraordinary to see a concise history of the use of any number of conservation materials, such as polyethylene glycol or boron compounds, from the time of their introduction through to the close of the 20th century. The “Advantages/Disadvantages” discussion about materials and techniques may be of particular value to the reader. This five-chapter section is certain to be useful for conservation scientists and conservators trying to understand an object's treatment history as well as to make informed decisions about its care. The extent to which the authors have gone to be as inclusive as possible cannot be stressed enough. The section on organic consolidants alone covers 118 pages, nearly 20% of the text.
Critical to the success of any book of this scope is the clear and complete referencing of sources. It is, in fact, one of the stated objectives of the book. The authors do include extensive reference lists for each chapter but come up short on identifying sources for some of their statements. For instance, they write, “There are known cases where the control of house fungi in masonry with borates has diminished plaster adhesion” (p. 259). This is interesting information, yet no sources are cited. It would help the reader to know where the authors found out about these examples. Are they published somewhere? Does this come from personal experience? In the same chapter, it is stated that “many objects of great art historical significance, are now in a condition … that no longer permits their presentation in exhibits due to toxic wood preservatives” (p. 261). This is a significant statement that may inspire the reader to know more, yet there is no apparent reference that would easily identify sources for further investigation.
There is an inconsistency in the use of Latin names for some living things, particularly woods. Common names are used in some of the tables while common and Latin names are used in others. The common name “poplar” can mean distinctly different woods to readers from various regions, whereas the Latin names Populus alba or Liriodendron tulipifera refer to specific woods, thereby avoiding confusion.
It is unreasonable to expect that all of one's own favorite publications will be included as references in such a book. However, it is disappointing that notable works such as R. Bruce Hoadley's Understanding Wood(Newtown, Conn.: Taunton Press, 1980) are not included. This is particularly unfortunate, as Hoadley's work is readily available and contains information that supports many of the points made by the authors. A. J. Panshin and Carl De Zeeuw's publicationTextbook of Wood Technology (New York: McGraw Hill, 1980) is nowhere to be found, yet it is a seminal work for anyone studying the nature of wood. The excellent reference from the Forest Products Laboratory's Encyclopedia of Wood (New York: Sterling Publishing Company, 1989) is also missing. Clearly much of the work by the authors was done in Europe, and it is reasonable to expect the reference lists to reflect that. However, a more complete representation of common publications, in addition to the more obscure manuscripts the authors rightly include, would have brought them closer to their stated goal to “systematically organize the extant literature” on the subject of wood conservation.
This is a landmark book for the conservation profession written by wood scientists who understand the need to establish a current, annotated, and well-referenced work on the research and publications related to wood conservation. It establishes a new level of professional scholarship on the subject of wood conservation by bringing together an extraordinary amount of information, research, and references in one volume. The history of materials and techniques used in preserving wood is humbling in that it underscores awareness that some of those materials and techniques have caused damage or created health risks despite the good intentions of the practitioner. A careful review of the “advantages and disadvantages” section for materials and techniques in each chapter may change the choices we make in these matters as well as force the profession to consider carefully all of the ramifications of wood conservation activity. The authors rightly point out in the preface that “the inevitable, gradual deterioration of objects should be slowed down and should not be accelerated by ill-considered conservation measures” (p. viii).
This is a publication that will require routine updates to stay relevant, a point that is stressed by the authors themselves. It is hoped that these authors, or their successors, will follow through with periodic revisions of the material presented, as new scholarship continues to be published. There is yet more work to be done in considering these very same issues from the perspective of decorative arts. What might the impact of various wood preventive or consolidation techniques be on gilded surfaces? How do pesticides and fumigants affect coatings and adhesives on furniture from various eras and regions? There is still research to be performed and collected for the profession to be better able to preserve cultural material made of wood. This book thoroughly reviews work done to date, providing a firm platform on which to base future work.
The merits of the book are so strong as to outweigh any concerns about completeness in some areas. Its importance to the conservation profession should not be underestimated. Any conservation scientist, conservator, or student involved in the preservation of wooden cultural material will want to have access to this publication. The Conservation of Wood Artifacts should be a core publication for any training program that includes the subject in its curriculum. The professional discipline of the three wood scientists who compiled this publication is apparent in their reliance on verifiable information, thorough referencing of other works, and avoidance of conjecture. Despite the exceptions identified above, the importance of noting most relevant publications is made very clear. The reference list for chapter 11, “Consolidants,” is 35 pages long and includes more than 600 publications. The conservation community is well served by this example of effective organization and the application of rigorous standards in presenting concepts supported by the extant literature.
Achim Unger, Wibke Unger, and Arno P. Schniewind have studied, written, and lectured extensively on the subject of wood conservation. Their collective work has shaped the way in which wood is understood and conserved by today's scientists and conservators. The professions of science and conservation are indebted to them for their previous research, as well as for producing this concise overview of what is known about wood and its preservation.
- Gregory J. Landrey
- Conervation Division
- Winterthur Museum
- Winterthur, DE 19735
RUTH JOHNSTON-FELLER, COLOR SCIENCE IN THE EXAMINATION OF MUSEUM OBJECTS. Los Angeles: Getty Conservation Institute, 2001. 385 pages, softcover, $80.00. Available from Getty Trust Publications, 1200 Getty Center Dr., Suite 500, Los Angeles, Calif. 90049. ISBN 0-89236-586-2.
Ruth Johnston-Feller's monograph, Color Science in the Examination of Museum Objects, is a distillation of her life's work, and a particularly welcome one at that. She states in the preface,“It is the purpose of this book to present some examples illustrating how the basic principles of color science can contribute to the understanding of the color and appearance of materials.” The book is aimed primarily at museum professionals and is written in a more approachable style than most textbooks dealing with color science. While the basics of spectrophotometry and colorimetry are presented, each in its own chapter, the bulk of the text deals with identification of pigments and pigment mixtures through measurement and interpretation of spectral curves. Many spectral curves carefully collected by Johnston-Feller over the years appear throughout the book, and they alone make it a valuable tool for researchers.
The book is quite successful in its practical approach to color measurement. Compared to most other textbooks that only discuss color theory, John-ston-Feller cites examples from her own experience in the measurement of real-world pigments and dyes. Whereas other textbooks only discuss computational methods for pigment mixture identification, John-ston-Feller gives insight into how one can make educated guesses about which pigments are present in a mixture simply by looking at a spectral curve. Several examples are given throughout the book that explain how to examine spectra for telltale signs that reveal the presence of a particular pigment. Modern researchers tend to ignore spectral details and rely solely on the colorimetric data that the instrument software gives them. For example, the double absorption bands of quinacridone red in the green region of the visible spectrum, the characteristic tails of phthalo green and phthalo blue in the red region of the spectrum, and the characteristic absorption of rutile titanium dioxide at the far violet end of the spectrum would be readily apparent in a pigment mixture containing any one of them.
There is also useful practical information about the various characteristics of spectrophotometers and colorimeters as well as the advantages and disadvantages of each. Johnston-Feller remarks that true spectrophotometers have resolutions of 2 nm or less, and that many commercially available spectrophotometers are really only “abridged” spectrophotometers in that they only measure 10–20 nm chunks of the spectrum. Interpretation of spectral curves can become tricky when such large amounts of information are lost; there might not be enough information to identify a pigment that is fading or to do proper color matching if one is trying to avoid metamerism. She also reminds the reader that the proper use of a colorimeter is to measure color differences between similar colors and that comparison of color differences using two different colorimeters is true folly.
Johnston-Feller cites numerous examples of analytical problems that she encountered over her long career. Consequently, interesting historical information, while not necessarily relevant to the discussion of pigment mixing and identification, is brought to light. In an introduction to the qualitative use of the Kubelka-Munk relationship, she explains why burnt umber was preferred to black back in the days when paints were adjusted visually by “tinters.” Although not neutral since it is noticeably yellowish, burnt umber's effects are easier to control than any black. She also relates the origin of the common misperception that a difference of one ΔE*ab unit is equivalent to a just-perceptible color change. The definition of the old ΔE unit developed by the National Bureau of Standards in the 1940s (now the National Institute of Standards and Technology) stated that measurements within one ΔENBS were good achievable commercial matches even though it was known to be two to four times the just perceptible difference. The “commercially acceptable difference” became confused with a “just perceptible difference” in people's minds, and this misperception was later transferred to the 1976 CIE ΔE*ab unit.
The great strength of the book lies in the later chapters and in the appendices. Although these later chapters are very brief, they highlight aspects of color measurement and data interpretation that are invariably overlooked by most conservators and scientists because such aspects are often never explicitly stated or are scattered throughout multiple sources. In chapter 7, Johnston-Feller gives very concise discussions of frequently encountered pigments and shows their spectral curves. This very short chapter can be of enormous help in aiding understanding of spectral differences between similarly colored pigments. Chapter 8 discusses the often poorly understood use of statistics. Johnston-Feller gives examples of when it is appropriate and when it is not to average color measurement readings. In chapter 9 she succinctly discusses the important features of color measurement instruments and what kinds of samples they best measure. In chapter 10, she gives a short discussion of a general measurement protocol and a much too detailed accounting of what information should be recorded. Appendix D is perhaps most useful to those who wish to collect libraries of spectral curves. She gives spectral curves for 32 different red pigments and describes the procedures for preparation of the samples, how to order and group the collected spectral curves, and what kind of information is important to record so that other researchers would be able to use the library as well.
Two additional chapters, while perhaps not the most critical for most conservators and scientists, contain information not typically found anywhere else in the conservation literature. Chapter 5 on color in specular reflection discusses not only metals but also iridescence and pearlescence, metallic flake pigments, and the phenomenon of bronzing. Chapter 6 deals with special topics, including fluorescence, geometric metamerism, contributions of gloss to color, microvoids and vesiculated beads, and extenders, fillers, and inerts. While most conservation laboratories will not have access to a variableangle goniospectrophotometer, which is necessary to completely characterize iridescent, pearlescent, and metallic flake pigments, as well as materials exhibiting bronzing and geometrically dependent color, it is quite useful to understand how well or how poorly the more commonly available color measurement instrumentation can provide information about these kinds of samples and why.
The shortcomings of the book are few, and they are primarily a result of editing. While the introductory chapters on colorimetry and spectrophotometry are useful, they are not as complete as they would be in other textbooks and could therefore give the novice in color measurement insufficient background to understand the basics of the theory. To her credit, Johnston-Feller continually refers to other books and papers within the text that treat the same topics. There is also an annotated bibliography at the end of the book that lists some of the best references on the subject of color measurement, so the reader is not left wondering where to go next.
The organization of some of the topics within the book seems rather arbitrary and somewhat illogical. Chapter 3 on colorant characteristics is only four pages long and should have been made a subsection of another chapter. Chapter 4 on colorant mixture, on the other hand, is approximately 25% of the book and contains a variety of topics jumbled together. The Kubelka-Munk Relationship is presented quite thoroughly in this chapter, and the use of examples is extensive and really helps one to understand how to use it effectively. However, the chapter has two different sections, one near the beginning entitled “Qualitative Application of the Kubelka-Munk Relationship” and another near the end entitled “Qualitative Applications of the Kubelka-Munk Relationship,” and they are separated by sections entitled “Quantitative Application of the Kubelka-Munk Equation” and “Applications of the Kubelka-Munk Formulas.”The disorder is not helped by the section and subsection headings appearing in the same typeface. A more unified progression from qualitative to quantitative applications would be easier on the reader.
Anyone interested in making proper and truly useful color measurements should carefully review this book. In her conclusion Johnston-Feller states,“It is hoped that the procedures and guidelines outlined will help the user avoid inappropriate color measurements—measurements made with instruments not carefully standardized; measurements made with instruments not suitable for the task at hand; measurements made with instruments whose reliability and reproducibility are not known; or measurements from which improper conclusions can be drawn out of ignorance.” She ends with a plea for the establishment of an atlas of spectrophotometric curves composed of contributions from academic, industrial, and museum research laboratories that would be available to all. Let us hope that her contributions will form the core of such a collection.
Ruth Johnston-Feller authored more than 50 technical publications in the field of color science throughout her two careers in industry and conservation. Her connection to the field of conservation began in the early 1960s when Robert Feller collaborated with her on a paper entitled “The Use of Differential Spectral Curve Analysis in the Study of Museum Objects.” After her marriage to Feller in 1970, she began working on a consulting basis with the Research Center on the Materials of the Artist and Conservator at the Carnegie Mellon Research Institute, Carnegie Mellon University. Her primary affiliations remained with industry, first with Pittsburgh Plate Glass, where she pioneered the use of instrumentation to measure and monitor color in an industrial setting, and later as director of application services for the Color Systems Division of Kollmorgen Corporation. Her last industrial position was with Ciba-Geigy Corporation, Pigments Division (now Ciba Specialty Chemicals, Colors Division). Ruth Johnston-Feller passed away in 2000.
- Christopher Maines
- Scientific Research Department
- National Gallery of Art
- Washington, D.C. 20565
JEANNE-MARIE TEUTONICO AND JOHN FIDLER, eds. MONUMENTS AND THE MILLENNIUM. London: James and James Ltd., 2001. 244 pages, softcover, $55.00. Available from James and James, www.jxj.com. ISBN 1-873936-97-4.
This book is a compilation of the edited papers presented at a three-day conference held in May 1998 at the Victoria and Albert Museum, London. English Heritage, the United Kingdom Institute for Conservation (UKIC), and the Public Monuments and Sculpture Association collaborated in organizing the conference. Planned as an international forum on conservation issues surrounding public sculpture and monuments, the published papers, as a group, have a much wider scope. They address historic and contemporary concepts of monuments, social context, monument types, changing constituencies, and changing relationships to physical surroundings.
I recommend this book less for the content pertaining to conservation issues than for the material about the historical form and meaning of monuments in European culture and the diverse expectations of artists and commissioning agencies at the turn of the millennium. The conference ideas are not out-of-date in 2002. If you are interested in the phenomenon of monuments and their inspirational value, you will enjoy the reading. If you are in a position to influence decisions about the creation, care, or destiny of monuments, you should welcome the opportunity this book offers to confirm or deepen your understanding of the complex issues you are asked to help resolve.
The book has a preface by coeditor John Fidler, whose closing remarks at the conference are published after the papers. Of the 24 papers, 13 are by English authors. Of the other 11, 3 are from Scotland, 3 from the United States, 2 from Germany, and 1 each from Ireland, Australia, and Italy. The authors often represent several disciplines, and authority is not always clear, but it might be said that we hear from about 10 practicing conservators. Those in other disciplines presenting papers are historians, art historians, curators, writers, architects, scientists, and public art administrators. Few authors confine their remarks to their own discipline, underscoring the point that meaningful statements about monuments usually represent multidisciplinary thinking.
The book is divided into five parts, which are reviewed in sequence below. The names of the parts are generally indicative of the subject matter, but typically they touch on issues explored more fully in other parts. For the reader who may not want to read the book from cover to cover, each article has a comprehensive abstract at the beginning and information about the author or authors at the end. The articles are generously illustrated with black-and-white images, and there are 12 pages of color photographs in the center of the book.
Part 1, “Context and Inventory,” provides an overview of the universe of traditional monument types and describes systems that have been devised for creating inventories. Reports on the program of the National Inventory of War Memorials and the Public Monuments and Sculpture Association National Recording Project give information about program organization, inclusion, and survey implementation. A short report from Save Outdoor Sculpture! discusses findings from its completed inventory and mentions current activities, including guidance for raising custodial and community awareness and assistance with funding individual assessment and treatment programs. A project in the City of Leeds provides an example of a conservator's assessment, or audit, which typically follows a general inventory and provides the technical and budget information that can lead to treatment and maintenance programs.
In part 2,“History and Interpretation,” the reader is introduced to the universe of monuments that are being studied, conserved, proposed, and realized in 1998. Examples are given of monuments with a purely local context. Cases of monuments changing their relationship to their environment as social and political situations change are exemplified by the issues of destruction or preservation of British imperial monuments in Dublin. The popular movements toward easily accessible monuments that rely on the quick effect or entertainment value are given thoughtful review. Two excellent papers address the intellectually challenging alternatives to traditional monument forms, including “invisible” monuments that poignantly convey a sense of absence. There is discussion of the value of each type of monument as an expression of the culture that produced it and the powerful trend at the turn of the millennium to replace the literal with the metaphor.
Part 3, “Technical Approaches,” contains much material about bronze sculpture conservation, but with only six papers, it cannot pretend to provide the general reader with a broad and balanced overview of technical approaches available in 1998. There are two reports of research in progress. The effectiveness and limitations of laser cleaning of bronze are discussed. Testing of an inorganicorganic hybrid polymer coating for bronze sculptures is described. Two articles speak about the theory and general practice of bronze treatment and raise some critical issues about the quality and long-term benefits of conservation programs. They raise the issue of lack of maintenance programs that would ensure the benefits of the cost of initial treatment. And they repeat concerns expressed by the chairman of UKIC in his introductory remarks at the conference about the number of practitioners who operate outside the ethical frame-work of conservation. It is pointed out that there is no enforceable regulation of conservation services to help protect clients from technically inappropriate treatments or inflated budgets. In fact, the two articles about conservation programs, in Melbourne and in Aberdeen, both include descriptions of some treatments that are more invasive than I would wish reported in this publication. It is unfortunate that the bronze treatments in Aberdeen were included. They are not good examples of responsible bronze conservation in 1998 as they utilize a one-treatment-fits-all approach. Moreover, the treatment described appears, to this practitioner, as if it must have resulted in more expensive and aggressive intervention than necessary to preserve each of these objects.
In part 4, “Case Studies,” the articles provide the reader with an insight into other aspects of professional conservation besides treatment. One article explores the value of considering conservation principles and practices in the design phase of conceptual monuments. Two articles describe conservation studies that resulted in stabilization but minimal surface treatment. One of the articles discusses the two granite obelisks in London and New York, each known as Cleopatra's Needle. The other study is of the Scott Monument in Edinburgh. These important articles prove the point that a monument does not necessarily need monumental treatment, and they demonstrate responsible action on the part of their custodians in identifying concerns and funding appropriate studies so that the perceived problems can be understood and parameters set for intervention. A case study of cathodic protection to a historic masonry structure provides an example of an imaginative team solution to a stabilization problem without major physical intervention. An article about the restoration of the Albert Memorial describes a different kind of team effort in which public officials, architects, art historians, conservators, and tradespeople, to name only some of the players, collaborated on a huge project. There is interesting discussion about the varying rationales for treating different components.
In part 5, “The Future of Public Monuments,” one article discusses the change in preservation philosophy in Italy during the final decades of the last millennium. Commissioning agencies are moving away from efforts to restore monuments and toward programs to conserve what remains and carry out preventive conservation measures. A program for commissioning new sculpture for Lincoln, England, raises complicated and timely issues about influence on design decisions and ownership of space. This program is interesting when compared with a description of the fate of public monuments in Leeds as changes have occurred in urban planning and social life. The last paper of the conference moves away from focusing on the fixed image as memorial, be it permanent or impermanent, and discusses the garden and the process of cyclical tending as a memorial concept.
In his closing remarks, John Fidler raises the question of what has been learned and what action needs to be taken to improve matters for the future. To the first question, this reviewer replies that the publication has shown us how various kinds of ideas and information fit together in the context of monuments conservation. Readers are much indebted to the conference organizers, authors, and editors for handing us so much in such an attractive package. We have learned of the various forms that monuments can take at the millennium, how they are cataloged and how we can have access to information about them, the kinds of agencies and custodians responsible for their care, and the disciplines involved in studying, reporting on, and designing treatment for them. We have learned that the concept and the physical realization of monuments required interdisciplinary endeavors, and we have learned that the most satisfying preservation programs result from team efforts. In this last idea, we find the answer to the second question, in that action to improve matters for the future must respond to the needs of many constituencies. If there are going to be generally accepted and regulated standards, they must represent a balance of the standards of all the professionals represented here.
We should be neither discouraged that there is so much more work to be done nor disappointed that the conference goals of creating consensus or setting standards, mentioned by the then-chair of English Heritage, were not achieved. In countless localities, conservators' ethics and standards of practice are being introduced into projects that a short while ago would have been designed and carried out without them. We need to remember that this is a relatively new field and recognize that all the players, both established and new, are jockeying for visibility. Professionalism is being developed in a very large arena where projects are driven largely by political forces. What can you do? You can put this book into your library, become familiar with the content, and use it for reference in speaking for your constituency as we move on.
- Virginia Naudé
- Norton Art Conservation
- 752 Germantown Pike
- Lafayette Hill, Pa. 19444