BOOK REVIEWS

Conservators are concerned with the long-term stability of materials and methods. One may ask, Who will test the countless products available? That is a rhetorical question. A very practical one is, How reliable are the testing procedures and the predictions derived from them? The answer is not very satisfactory, but the question is being actively pursued today in chemical and engineering laboratories everywhere. Here we have three recent publications dealing with the subject. What do we find between covers bearing such promising titles?

The first book will be of interest to laboratories carrying out accelerated aging tests. It consists of papers given at a 1993 meeting jointly sponsored by ASTM Committee G-3 on Durability of Non-Metallic Materials and Subcommittee D01.27 on Accelerated Tests. The authors are actively engaged in studying current photo-aging test methods and ways to improve them. The first part consists of eight papers on “Characterization of Exposure Tests.” Among the topics: the character of solar ultraviolet radiation (G. A. Zerlaut, SC-International); the effect of spectral distribution of the light source (N. D. Searle, consultant); errors in monitoring exposure by use of Joules at one specific wavelength (D.M. Grossman, Q-Panel); surface temperature of samples (R. M. Fischer and W. D. Ketola, 3M Center); and ultraviolet transmission of window glass (Ketola and J. S. Robbins III, Heraeus DSET Laboratories). A report on the results of round-robin studies of standard practices in light-and-water-exposures reaffirmed that the reproducibility of results remains highly variable both within and between laboratories.

The last seven papers, on “New Test Methods,” include a discussion of irradiance control in fluorescent ultraviolet-lamp exposures (G. R. Fedor and P. J. Brennan, Q-Panel); variability in high-irradiance xenon-arc tests (K. P. Scott, Atlas Electric Devices); development of simulated acid rain tests (S. Suga and S. Suga, Suga Test Instruments); and life predictions for compact discs (W. T. Murray, 3M Center). Colleagues familiar with accelerated photochemical-aging tests will recognize the prominence of some of the authors and the companies with which they are affiliated.

Methodologies for Predicting the Service Lives of Coating Systems is a new issue in the authoritative series of booklets produced by the Federation of Societies for Coatings Technology. For anyone so bold as to set out to find the “cause” (however loosely or precisely defined) of failure of a given system of materials, the first half of this booklet presents a sobering introduction to that task. A fault-tree diagram (much like the common organizational chart or family tree) of numerous possible roots of two common modes of failure in coatings—corrosion/blistering and chalking/gloss retention—provides an object lesson in just how difficult it is to designate a specific cause of failure, whether some aspect of application, materials processing, environmental conditions, or an inherent property of the material under test. Included in the discussion is a criticism of our current approach to lifetime prediction. The last half of the 20 pages of text, not so easy reading, presents an authoritative discussion of the methodology based on reliability theory, an approach that has been applied for some time in testing electrical and mechanical systems. The mathematical expressions—based on the Weibull distribution function, a probability distribution—do not require that the experimenter wait until all supposedly identical samples have failed before arriving at a meaningful lifetime prediction. The equations may not speak clearly to every reader, but a glance at a few of the 17 figures should readily convey many of the essential points the authors wish to make. Considering the authority, price, and convenience of the 8 1/2 � 11 in. three-hole-punched booklet, certainly the early pages should be required reading for anyone beginning to study this subject.

The American Chemical Society's Polymer Durability contains 39 papers from a symposium at which an internationally recognized group of chemists described some of their latest research concerning the chemical mechanisms by which various polymers deteriorate. The audience undoubtedly consisted of scientists pursuing similar interests, colleagues not needing elaborate explanations of the what and why of particular projects. Five of the papers deal with the use of chemiluminescence. About a quarter of the book concerns studies of the behavior of inhibitor-antioxidant systems. Another quarter of the papers involve studies under nitrogen above 200�C, gamma radiation, and wavelengths of ultraviolet far shorter than those that pass through window glass, conditions not likely to be of pressing interest to many in conservation. The conservation scientist would have to study each article carefully to see if some of the approaches described would be of use in one's own research. Borrow a copy before buying.

As is often the case with such works, in all three volumes the bibliographies that the authors provide represent excellent up-to-date overviews of the particular research topics treated.

The Museum of Fine Arts' collection of keyboard instruments includes some particularly fine instruments, historically and musically, many of which are also good examples of highly decorated cabinetwork of the 16th through the late 19th century. Although written from the point of view of art historians and musical instrument specialists, this catalog contains much of potential interest to conservators, conservation scientists, and historians of material culture. Detailed descriptions of the decorative and constructional details of 54 of the 61 European and American keyboard instruments in this important collection are each given from two to 20 pages of text, footnotes, and illustrations; the catalog includes 16 color plates and several hundred black-and-white photographs and line drawings. It is significant that the presence of nameboards and other inscriptions and guild marks give many of these instruments well-established attributions for maker, date, and place of origin, along with documentary records of their history of ownership, thereby eliminating one problem often encountered when studying examples of historical furniture and decorative arts lacking labels or maker's marks.

Those unfamiliar with the vocabulary of American and European keyboard instruments will welcome the more than 10 pages of glossary for such arcane terms as “stoss-mechanik,” “dogleg jack,” “bung board,” and “Venetian swell,” most of which would otherwise be impenetrable to nonspecialists armed only with a standard dictionary. This glossary, coupled with the “Brief Overview of the History of Keyboard Instruments” included in the author's introduction (five centuries condensed into just over two pages!), gives enough basic information to permit someone unfamiliar with the subject to read the technical and historical entries with understanding and even enjoyment.

The author is now conservator and associate professor of museum science at the Shrine to Music Museum at the University of North Dakota (Vermillion). His experience as a maker of harpsichords patterned after historical models and his work as a technician and conservator at the Museum of Fine Arts strengthen the deeply technical descriptions of structure, function, and alterations, all of which are more detailed and analytical than is often the case with collection catalogs. Old musical instruments have been routinely redecorated and altered to suit changing fashion and the desire to keep them functioning, so it is often very difficult for the nonspecialist, whether conservator or curator, to know with any certainty whether the instrument depicted in a catalog illustration bears much resemblance to any authentic historical state. The author's collaborators, Sheridan Germann and John T. Kirk, contributed art-historical expertise on the authenticity and attribution of the painted surfaces, furniture styles, and decorative features, and their opinions are included in the entries for many of the instruments.

Conservators with an interest in the practical and ethical dilemmas that so often accompany the treatment of functional objects such as clocks, vehicles, industrial machinery and musical instruments will find much to appreciate in Koster's careful descriptions (expressed in a discreetly indirect fashion) of the sad loss of original decorative, functional, and historical data caused by well-intended restorations over the years. For example, the entry for a virginal made by Andreas Ruckers the Elder, Antwerp, 1610, demonstrates the erosion of original substance and outright alteration found all too often in functional objects:

Condition: The instrument is in good condition … retaining its original scalings, compass, sound-board structure, and significant portions of its action. … Extensive wood worm damage might have led to the replacement of the nameboard, jack rail, treble jackrail holder, most key levers, most jacks, front molding, tool-compartment cover, lid, and lockboard.

The listing of lost parts and additions continues, ending with the information that the stand and exterior paint are also modern additions—all this in an instrument considered (perhaps not unreasonably, considering its nearly 400 years of age) to be in “good” condition! One of Koster's footnotes to this section adds that this is one of only two Flemish virginals that retain a movable batten with little metal hooks (arpichordium) designed to alter the sound of the bass strings. “A careful examination of most muselars [instruments of this type] that have not been drastically altered, restored, or cleaned [emphasis added] will usually show traces of such a batten along the bass section of the bridge.” In his entry for an early-19th-century square piano, Koster notes: “A restorer in the 1960s wrote in a progress report that he had 'piled into the Astor with a vengeance. …' The well-scrubbed instrument bears many signs of such treatment.”

These and the many similar accounts of loss of original substance should make this catalog suggested reading for those who perform routine maintenance and treatment of functional objects, because Koster has so clearly detailed the sad consequences of what was until recently the standard approach to care and treatment of historical musical instruments. Although the problem has been addressed in the past decade or so in a few specialized publications and conferences, the message needs wider circulation, not just among conservators but among curators and custodians of collections of musical instruments, vehicles, clocks, industrial machinery, and other functional objects. Those who want to pursue the matter further will find much of interest in the publication, Recommendations for the Conservation of Musical Instruments in Collections: An Annotated Bibliography, edited by Robert Barclay. (CIMCIM Publications No. 1, International Council of Museums, Paris, 1993. Available from Arnold Myers, CIMCIM Secretary, Edinburgh University Collection of Historic Instruments, Reid Concert Hall, Bristo Square, Edinburgh EH8 9AG, Scotland, or on the World Wide Web, at http://www.music.ed.ac.uk/ euchmi/pubs/iwt1.html.)

Those interested in the history of fakes and forgery will appreciate the discussion and photographs of five instruments (nos. 1, 2, 3, 4, 53) typical of those that passed through the shop of the notorious Florentine forger Leopoldo Franciolini, other examples of which can be found in many museums in the United States and Europe. Although Franciolini was best known for the inventive redecoration, elaboration, and outright fakery of musical instruments, his trade literature also mentions ceramics, furniture, coins, and medals.

The book includes a 16-page bibliography and an 8-page “Index of Names,” mostly consisting of makers, collectors, places, and scholars. Materials and techniques are not indexed. Given the book's wide potential audience and the obvious care and expense that went into its production, this omission is surprising, especially because of the many references to the most common, and many of the less common, materials of furniture and decorative arts throughout the text, captions, and footnotes. Searching the entries for technical information can be both rewarding and annoying, because of the quantity of interesting but unindexed information that must be ferreted out bit by bit. One yearns for a CD-ROM or similar digitized edition with random access search capability. This approach to indexing poses particular challenges in the case of materials, such as wood, that are well represented in the text. The author identifies many examples of wood species through microscopical examination; further technical and historical information is given for a few in a brief appendix on wood terminology. (Since the emphasis on technical features is a major strength of this catalog, it is also somewhat surprising that scientific examination was mostly restricted to wood species identification and that, the author writes, “other materials including leather, bone, ivory and metals have been identified only by eye unless otherwise noted.”)

The author makes reference to wood of the genus Manilkara in the description of the hammer mechanism of a piano by the London maker John Broadwood (no.29). It is not included in appendix B, “Wood Terminology,” or cross-referenced in the index, but the entry for its use in another Broadwood piano of 1794 (no. 25) adds that Manilkara is “known, for example, as bullet wood or horse-flesh wood.” This identification of a wood from the semitropical forests of the New World, used in instruments made 10 years apart in London, shows the effort that preindustrial craftsmen and their suppliers would make to find and use natural materials with properties well suited to a particular mechanical function. It is unfortunate that such information is not easily accessible through an index.

The banishment of the seven most recent instruments to cursory one-paragraph notes in appendix A, “Modern Instruments of Historical Type,” is disappointing, despite the author's explanation that “to have described and discussed them more fully would have been to turn from the study of history to that of history's interpreters.” One could also argue that this encyclopedic work will certainly remain the principal reference to this major collection for a long time; the last previous catalog, by Nicholas Bessaraboff, was published in 1941. What better time than now to have thoroughly documented the entire collection, including these examples of the work of such seminal modern craftsmen and “interpreters of history” as Arnold Dolmetsch (nos. 57, 58), and William Hyman (no. 61)?

These minor annoyances are outweighed, however, by the many strengths of a fine work that will serve several audiences, including those interested in an overview of the history and nomenclature of keyboard instruments, conservators seeking examples of materials and methods used in historical cabinet making, and others simply looking for detailed information about American piano actions of the last century. The descriptions are all enlivened by frequent glimpses into the lives and times of those who made and used these instruments.

Cleaning Historic Buildings is a two-volume survey addressed to a wide audience ranging from owners, building managers, and surveyors to architects and conservators. The material covers both philosophical and technical issues based on experiences with historic buildings in the United Kingdom. Because building conservation is now a worldwide concern, the book attempts to cover many disciplines and subjects using British landmarks to illustrate internationally recognized problems. These volumes present a significant amount of information with special emphasis on cleaning, but the subject is overly complicated by the organization and segregation of the material.

The two volumes make an important contribution to the field of architectural conservation by bringing together the theoretical issues regarding the rationale behind cleaning buildings and the technical issues of the actual procedure. The author≈s vast professional experience is evident in the number of important buildings included as case studies. Unfortunately, the books also combine several formats—reference book, textbook, and method or recipe book. Since the author does not target a specific audience in either volume, she repeats information to suit her readers' different levels of expertise. For example, there are redundancies in the two introductory sections, “Attitudes to Cleaning” in volume 1 and “Selecting a Cleaning Method” in volume 2.

Both volumes are heavily illustrated, but the photographs of buildings and sampling procedures, with the exception of those included in the case studies, are not referenced in the text. When photographs illustrate completed cleaning projects that exemplify complex testing processes and cleaning methods, both before-treatment and after-treatment images would have been instructive, particularly because so much evaluation of a successful cleaning project is based on visual observation of efficacy. The matte finish of the paper reduces the quality of the photomicrographs, most of which are not clear, and the scanning electron microscope (SEM) micrographs (vol. 1, fig. 2.10, for example) do not include magnification bars.

In volume 1, the first chapter and half of the second provide a basic introduction and discussion of the issues relating to cleaning, directed to building owners and managers. This portion fails to provide a complete overview of how a building conservation project is organized and launched, including project planning, the role and responsibility of the different disciplines involved, the impact of contracting the work, and the time frame. These topics are essential to understanding the process and scheduling of a building cleaning project. Today, costs associated with large or complex building facades can be enormous, and without a clear definition of the goals and the scope of work, the coordination of disciplines, and the role of the owner, any analysis and evaluation can be lost. Here the process of cleaning a building is not described coherently. For example, the purpose and importance of a specification, which results from the testing and analysis stage, are not emphasized, nor are the roles and responsibilities of different professionals, which should be clearly stated once a project is contracted and before work is in progress. Unlike other conservation fields, in building conservation, most cleaning efforts are carried out by workers who are not conservators. The author makes this point but offers no suggestions for coordination between professionals and the building trades. Such cooperation can reduce the risk of misinterpreting the work or carrying it out incorrectly.

As the author states, she is influenced by the current polemic of sandstone cleaning in the United Kingdom. Thus this topic is addressed in great detail and includes previously published material such as section 2.13, “Analytical Approach to Sandstone, Its Cleaning, Repair and Treatment.” This discussion includes complex chemical analysis but does not adequately cover the extremely important issue of clay content. In chapter 4, where sandstone is covered again, there is no reference to studies carried out on this type of stone outside the United Kingdom, although the cleaning and deterioration of sandstone has been a topic for architects and building conservators in the United States and Germany for decades. This split discussion will confuse readers seeking specific information because of the disjointed way the material is presented. While the book attempts to separate methodology and theory, the insertion of explanatory sections results in jumbled content.

Chapter 2 of volume 1, “Understanding Building Surfaces,” is probably the most complex chapter of all. It starts with an introduction that lists the aesthetic and technical considerations that must be taken into account during cleaning. The discussion is fairly comprehensive and well thought out. The next sections review the issues of surveying, characterization, test cleaning, and specification. Subsequent sections deal with the required analysis, attempting give a thorough explanation of the analysis procedures. Chapter 2 provides far more detail than is required for managers, owners, and even architects; at the same time, it lacks sufficient data for conservators, who would already be familiar with this basic material, and it is not specific enough for contractors, who most often carry out the work. Because so much material is covered, the chapter includes some poorly defined statements, such as the following awkward and contradictory passage from the subsection “Other Microscopic Techniques”: “Samples of stone need to be removed from the building [for SEM analysis]. It is therefore not practical to inspect large areas of the same surface before and after cleaning” (section 2.10, p. 49). The subsequent discussion of porosity and capillarity (also in this section) defines the capillary network as “comprising the microporosity which is usually taken as less than 2–5 microns diameter” (p. 51) from a personal communication. It seems unfortunate that this definition does not make the distinction between capillary and micropores, which are generally considered two different pore groups. Section 2.12, “Analysis and Abrasive Cleaning,” mentions only surface roughening and surface loss as the alterations that can be induced to the stone surface. However, microfissuring of the stone grains, which is a serious problem since it would enhance capillary water uptake, is not mentioned.

Chapters 3 through 5, “Soiling,” “Masonry Substrates,” and “Cleaning Metals and Timber,” are fairly concise and practical from the point of view of a conservator and an architect. Chapter 5, “Cleaning Metals and Timber,” treats this subject in far less detail than do the masonry portions of the book. This focus may be due to the fact that metal and timber are rarely left as exposed “natural” components on building exteriors without some type of protective coating or covering. Consequently, the chapter emphasizes paint and paint removal. Unlike the extensive illustrations and descriptions used in the discussion of masonry issues, few pages are devoted to removing paint from wood substrates. This section fails to adequately outline the pitfalls associated with incorrect or overly harsh removal processes applied to timber cleaning. For example, it does not explain that chemical strippers can corrode nailed and screwed construction or dissolve glues used in laminated or veneered interior features, and it does not describe the problems associated with removing previously stained surfaces, which can bleach substrates or turn them gray. Presumably, the author is referring only to wood components that are ultimately to be repainted. If this is the case, there is no mention of measures to be taken for repainting cleaned surfaces, the care required to specify compatible materials, and the need for adequate surface preparation that may involve sanding and the application of primers and sealers. For both metal and wood there is little distinction made between structural members and ornamental features constructed of these materials, and there is no statement that cleaning may expose far more significant deterioration and component failure. While safety standards are briefly mentioned, no cautionary advice is offered for removing lead-based paints and other toxic materials that can contaminate groundwater and vegetation and harm adjacent surfaces. There is also no statement regarding the handling and disposal of waste products, either from a chemically applied removal system or from abraded or blasting techniques, which can be equally toxic. This issue is particularly important when the author discusses in situ cleaning.

Volume 1 concludes with four case studies: an ancient monument, Cleopatra's Needle (previously published); a church, St. Mary's Gateshead; an institutional building, Faculty of Art and Design, Birmingham; and an industrial building in Swindon. These examples give a fair cross section of regional architecture and construction periods to illustrate cleaning methodologies, but they focus on masonry and not on other building materials. It would have been informative to include some comparative information on the cost per square meter for the different treatments and the time it took to complete each project, during analysis and evaluation as well as actual cleaning.

Volume 2 contains an introductory chapter on “Selecting a Cleaning Method” (discussed earlier), providing the general approach to this topic. The chapters on more detailed methods, “Water Washing” and “Mechanical and Air Abrasive Cleaning,” are good surveys of current knowledge. “Water Washing” addresses spraying, nebulization, pressure, and steam washing and describes the problems associated with each method and the surface conditions required to safely apply them. “Mechanical and Air Abrasive Cleaning” covers dry and wet methods as well as microblasting techniques. The potential damage of employing these methods is well addressed, and the chapter concludes with a useful section giving the technical parameters for the various abrasives and nozzles available, as well as suggestions for making the right choice.

Chapter 4, “Chemical Cleaning,” leaves much to be desired. This Chapter shows the difficulty of a single professional trying to cover the full range of conservation topics. The result is unevenness in presentation, even typographical errors in formulas: sodium carbonate should be [Na2 CO3], not [NaCO3] and sodium bicarbonate should be [NaHCO3], not [Na(CO3)2], both on page 53; ammonium carbonate should be [(NH4)2CO3], not [(NH4CO3], and a strange formula for sodium hexametaphosphate mixes chemical symbols with practical abbreviations without differentiating them, both on page 74. Oversimplifications are inevitable. For example, section 4.7, “Chemical Cleaning and Sandstones,” cites the effect that hydrofluoric acid can have on the different minerals contained in sandstones, but it fails to mention that this acid, or ammonium bifluoride, is also capable of etching silica.

Chapter 5, “Special Cleaning Systems,” and chapter 6, “Specific Cleaning Problems,” also show the difficulty of writing accurately about another discipline. As a conservator, Nicola Ashurst clearly differentiates a “poultice” from a “pack,” but she uses the terms “soap” and “detergent” interchangeably, although they are also precisely defined: soap is an alkaline salt of fatty acids, and detergents, according to Chambers Science and Technology Dictionary, are “soapless cleansing agents containing surfactants which do not precipitate in hard water.” The “non-ionic soaps” mentioned on page 85 are an inaccurate term that is confusing for readers who require an understanding of the scientific principles guiding these classifications and the behavior of materials.

In chapter 6, the subsection on “Chelating Agents” is an oversimplification of the conditions under which EDTA is capable of complexing iron and calcium ions. Hence, the section does not further the understanding of the use, and misuse, of this ubiquitous compound. The subsection on removal of efflorescence is puzzling. It mentions the availability of “chemical efflorescence treatment systems,” which can be more problematic than the original problem. The whole issue of efflorescences and soluble salts leaves much to be desired throughout the book. It is repeatedly stated that they constitute a problem, and the removal systems are discussed in detail, yet the most common and/or most dangerous salts are not identified. The soluble salts referred to are always undefined chlorides or sulfates, yet no mention is made, for example, that sodium sulfate is more detrimental than sodium chloride. Section 6.9, addressing “Preconsolidation of Friable Masonry,” seems logical, as consolidation would normally be required prior to cleaning. However, the next section on water repellent treatments either should not have been included or should be more thorough. Given the current concern for sandstone deterioration and treatment in the United Kingdom, it is unfortunate that no mention is made of the problems encountered in the interaction of water repellents with the claycontaining sandstones that are susceptible to hygric swelling. There is also no mention of structural problems associated with the failure of unit masonry and water ingress to walls and how these problems can be mitigated when cleaning buildings with chemical solutions and water applied under pressure. Finally, in this chapter there is an unfortunate typographical error on page 109, for the pH 0.7–8.5; it should read 7.0–8.5.

Chapter 7 is a straightforward account of graffiti and paint removal, primarily from masonry surfaces. The explanations of the different removal methods are concise and informative regarding efficacy and dwell times. This section is suitably illustrated with diagrams and tables that are presented in a useful format for specifiers and building trades. The importance of paint removal trials is clearly demonstrated in log notes and photographs keyed to annotated diagrams. Trade name products are also listed with their main active ingredient so that chemists, conservators, and specifiers can refer to the process notes easily. This chapter is perhaps the most informative regarding the application and monitoring of cleaning paint from masonry.

Chapter 8, “Essential Practicalities and Preliminaries,” should have been included in volume 1. It describes the necessity of a coordinated team of professionals, although there is little advice for the client about how to locate specialists in this field. It does outline the criteria for selecting the contractor and suggests issues to be raised when agreeing to a contract for services.

The second volume is by far the most useful and interesting to read on the subject, despite the shortcomings cited in this review. While the author chose to present provocative questions in a list format, this volume gives practical and understandable methods and processes for undertaking cleaning from a conservation vantage point.

Building conservation is an interdisciplinary field and requires the expertise of different professionals to address problems jointly. Cleaning Historic Buildings is a tour de force from one conservator who has obviously had long experience in stone conservation and has given much thought to the problems encountered in the field. The background information as to why cleaning should, or should not, be carried out is important, together with the lists of aesthetic and technical questions. The author clearly outlines the scientific and technical methods available and the philosophical arguments for cleaning historic structures. The criteria and investigative requirements are well thought out and provide a clear understanding of the subject to managers who are unfamiliar with conservation practice, while the detailed technical information that follows these topics is addressed to practitioners. There are few books that attempt to cover this complex topic at so many levels. In spite of their shortcomings, these volumes go a long way to filling this gap.