Conservation Science

Heritage Materials

Paul Garside, Emma Richardson, Paul Garside, Emma Richardson

• Éditeur: Royal Society of Chemistry
• Année: 2021
• ISBN:
  9781788019347
• Édition: 2
• Sujet: Sciences physiques
• Sous-sujet: Chimie analytique

Conservation techniques for the analysis and preservation of heritage materials are constantly progressing. Building on the first edition of Conservation Science, this new edition incorporates analytical techniques and data processing methods that have emerged in the past decade and presents them alongside notable case studies for each class of material.
An introductory chapter on analytical techniques provides a succinct overview to bring the reader up-to-speed with which type of material each technique is suitable for, the differing sampling techniques that can be employed, and the handling and processing of the resultant data. Subsequent chapters go on to cover all common heritage materials in turn, from natural substances such as wood and stone to modern plastics, detailing the up-to-date techniques for their analysis.
With contributions by scientists working in the museum and heritage sector, this textbook will interest students, scientists involved in conservation, and conservators who want to develop their understanding of their collections at a material level.

1

Introduction

C. Rogerson

British Library, 96 Euston Road, London, NW1 2DB, UK

Email: [email protected]

1.1 Conservation as a Multidisciplinary Profession

Perhaps the stand-out feature of the conservation profession is its multidisciplinary nature. A conservator assimilates a widespread range of information in order to consider the stability, care and interpretation of cultural materials. Typically, a conservator draws information from the broad areas of humanities and science, and then combines the data by means of practical decision making and often hand skills. Resultantly these arenas of knowledge end up cohabiting the same space when applied to an object since separating the scientific data from the cultural significance is artificial, if not impossible.

The main purpose of this book is to reinforce and enhance the understanding and interpretation of material culture by elucidating the science required for conservation purposes. By addressing the science aspect, and more specifically the analytical methods available to assemble information about the materials in hand, the book ultimately aims to support the entire multidisciplinary process of conservation.

Not that all conservation processes are identical or that conservators have matching skill sets or roles. An increasingly wide range of specialisms exists in the profession. Whilst some conservators will work directly with objects daily, others may do this only as part of their role and others again may be concerned with processes of risk management to care for collections more holistically. Individual conservators may specialise quite closely on one material type or group of related materials, whilst others may be required to apply knowledge across a range of materials as multicomponent objects or collections are repeatedly encountered. What underpins each strand of the conservation profession, however, is a desire to prolong the life cycle of cultural materials to enable interpretation and use for the enrichment of society now and in the future.

At its root, the process of achieving the longevity of heritage material is a series of interrelated investigations enabling decisions to establish a course of action or actions for a single item or a collection. In this respect, further similarities exist between seemingly disparate roles across the conservation profession. Ultimately, this sequence of investigation and decision reduces risk to cultural materials through the understanding of composition and structure, identifying the nature, cause and extent of deterioration pathways and enabling judgements to be made on how stability may be achieved. Conservation activities may be interventive in nature but not in every case, since altering the surrounding environment can often be effective enough. Additionally, the investigation and treatment process can purposefully, or potentially unexpectedly, reveal more information to enhance interpretation and historic appreciation of the material. Unseen detail, underdrawings, atypical material, hitherto unrealised alteration or a maker's mark, to name a few, can potentially be discovered in the course of conservation work.

A conservator customarily has ready access to sophisticated investigation techniques. Eyes and hands provide observation and touch. Combined with taught and accumulated knowledge and the ability to interpret the evidence presented by collection material, an enormous quantity of information is gleaned and posited by these methods. Oftentimes this may be sufficient. Equally, there will be occasions where it is not and key questions remain.

The analytical techniques presented in this volume therefore endeavour to reveal additional information or sometimes hidden evidence that cannot be detected or discerned reliably by eyes or touch alone.

1.2 By Chapter

The book augments an existing corpus of conservation science publishing and brings an understanding of materials and application of analyses and treatments up to date. The previous edition (2006) provided an emphasis on archaeological materials and contexts in particular.¹ This newer version includes additional materials and emphasises the application of currently available methods of analysis. Other conservation science texts complement the information presented. Lister, for example, specifically discusses the chemical composition of materials to understand their behaviour in cultural materials.² Shashoua promotes the understanding of the vast subject area of plastics in the framework of heritage by considering their chemical composition, manufacture and deterioration pathways.³ Timár-Balázsy and Eastop present textiles within the context of science as a means to promote better decision making for treatment and empathy with differing contexts. Other texts centre specifically the on the choice of materials for treatments.⁴ Horie accentuates the requirement to understand the behaviour of resins and other polymers for treating items, particularly since once applied they cannot be easily removed or reversed.⁵ Varella meanwhile, introduces the theoretical aspects of instrumental analysis within the conservation discipline and gives examples of applications on several materials.⁶

What is distinctive in the present volume is that it is designed as a single point of reference and starting point for conservators seeking to understand a range of materials within the context of science and analysis. Whilst the text does not seek to cover any single material in infinite detail, the reader will gain sufficient knowledge of the materials to appreciate, select and apply appropriate investigative methods.

Bearing in mind that this volume is intended as a starting point for conservators seeking to understand analytical techniques, Chapter 2 opens up the subject area by describing the main analytical techniques currently available. The reader is encouraged to understand that the most appropriate technique is selected by bringing together the material type and research question to be answered and through understanding what differing techniques can achieve. The practicalities of sample requirements and the nature of the results are equal considerations. Matching the most appropriate technique or techniques to the scenario in hand is imperative to operative and cost-effective analysis.

Each subsequent chapter examines a different material or group of related materials. Organic and inorganic materials are included in this volume and both moveable and non-moveable heritage addressed in contexts ranging from archaeological to the modern day. This in itself demonstrates the wide-ranging circumstances where analysis can enhance the preservation, use and interpretation of material culture. Broadly, each chapter introduces the material composition, comments on deterioration pathways before addressing the main analytical approaches available to characterise the material and to help understand its vulnerability and condition.

Not all analytical techniques are complex or expensive. Whilst many may require equipment that is intricate and potentially costly this is not always the case. Chapter 3 focuses on paper, and highlights two major deterioration mechanisms, which can alter and disrupt its stability. Spot tests, perhaps the simplest tests available, are described alongside more complex possibilities with insight as to the most useful.

Wood is encountered in cultural heritage in a very wide range of environments from archaeological contexts to fine and applied art and buildings. Chapter 4 addresses the challenges of comprehending and detecting the deterioration mechanisms that can result in such varied applications.

Differences are also noted between perhaps superficially similar materials in Chapter 5. Leather and parchment have differing properties as a result of their manufacturing processes despite both originating from animal skin. Divergent deteriorating mechanisms are addressed alongside means to determine the animal species and ways to understand the degradation state.

Metal and associated alloys are introduced in Chapter 6 and continue the theme of variability within a material group. The occurrence and severity of corrosion on metal are related not only to its environment and application but also heavily depend on the composition of the material itself. Techniques to comprehend both the composition and deterioration of metals are described.

Additional inorganic materials are explored in Chapter 7, focussing on glass, ceramics and enamelled objects. Here the technology to create these materials is emphasised, because understanding manufacturing methods helps elucidate the subsequent behaviour and deterioration. Techniques for both laboratory based and mobile set ups are considered addressing the fact that conservation is undertaken both by bringing material to the conservator and, in situ, where the conservator is the moveable asset.

Chapters 8 and 9 explore colouring materials and their variety. Chapter 8 focuses on the similarities and differences between dyes and pigments. Various contexts are presented from works of art to a case study of Le Corbusier's use of colouring materials to present classifications and differing perspectives. Paint and binding media are explored in Chapter 9 to suggest analytical strategies for protein and oil-based media using intricate and intimate instrumental analysis with necessary samples, albeit small. Case studies address both more established and newer 20th century artist materials.

Textiles are the focus of Chapter 10. Ubiquitous in society but also sometimes overlooked because the multiple layers of historic evidence and significance are lost in their overall familiarity, the most commonly met types are placed centre stage.

The final Chapters 11 and 12 explore materials encountered within history that is more recent or through predominantly contemporaneous acquisitions; plastics and 3D printed material. Plastics have a growing familiarity within heritage collections and their deterioration is also becoming a customary element of conservation knowledge. Chapter 11 emphasises how the mechanical and thermal characteristics of plastics are assessed and investigated via analytical strategies for investigation. Items created via 3D printing may be less familiar generally. Chapter 12 emphasises their structural possibilities and material compositions to bring these possibly lesser-known pieces to attention.

1.3 Applied Science and Emphasising Practical Application

Applied science is the use of scientific processes and knowledge as the means to achieve a particular practical or useful result. Conservation science is a branch of applied science since conservators are inherently practical problem solvers who apply knowledge to a scenario.

Whilst the aim of the book is to position and strengthen conservation science within the professional discipline, a prime objective is to draw the fields of practical conservation and conservation science closer together via a common purpose. The techniques and applications described throughout the volume are concerned with aiming for and obtaining meaningful and useful results. Unapologetically so. Current economics within the heritage industry rarely allow for analysis as merely an academic exercise. Equally, well-intentioned research into processes and deterioration pathways that ultimately lack useful application for conservators ‘in the field’ seems profligate given the extent of cultural heritage needing attention. The contributors to this volume emphasise the application of science for conservation to bridge the gap between pure science and applied practical analysis to aid care and treatment decisions.

Accordingly, the volume is not describing how to develop new techniques, research, or pure science but rather how to apply established knowledge and analytical techniques to situations and materials encountered. That is not to say the conservation profession and allied conservation science professionals do not or cannot develop new scientific knowledge, far from it. Nevertheless, the intended focus of this volume is to inform and guide conservators in a hands-on sense using existing technologies and applying up to date understanding and processes, rather than generating new methods. Ultimately, new ideas in applying techniques to additional scenarios may result.

1.4 The Enduring Importance of Communication

Despite holding a diverse skill set, a conservator does not work in isolation. A key aspect of successful conservation decisions is collaboration with other specialists. To appreciate historic and current significance and determine future uses for cultural materials that are inclusive and empathetic, teamwork with the creators and user communities can be imperative. Equally, in facilitating conservation science and interpreting the resulting data, partnership and discussion with science professionals can be required.

The second objective for this work, connected to the first is, therefore, to enhance communication. A long established but growing feature of the conservation profession is the ability to communicate with others. As noted above, drawing science and conservation closer together requires a clear understanding of the reasons for and output of the analysis. Successful analysis is achieved through being able to establish and communicate the question to be answered and then understanding how it may be resolved. Appreciating the process, advantages and limitations of a technique for a particular material, therefore, seems fundamental to suggesting scientific analysis and communicating with a scientific specialist to achieve this. Not least in understanding the resultant data sets.

Furthermore, communication within conservation science is not just an internally focussed activity for the process of enhancing treatment decisions. Communication is an increasingly externally focussed endeavour. Behind the scenes tours of conservation studios, museum stores and heritage sites are enduringly popular for visitors to these institutions. The British Library has been hosting twice-monthly sell-out visits to the Centre for Conservation since its opening in 2007. Demand is not waning. The Victoria & Albert Museum, Birmingham Museums, Fishbourne Roman Palace, Chichester, and the Peoples History Museum, Manchester are just a mere snapshot of the institutions where tours, viewing areas and open days allow access to the normally unseen realm of the heritage professional and conservation in particular. Visitors seek to learn more about the process of conserving heritage and conservation science is a component of this story.

The growth of social media has triggered a steadily increasing expectation to communicate more widely. Despite the prolific output of social media platforms, the quality of the information is imperative to represent the heritage industry successfully. Conservators are progressively contributing to this newer web based agenda and learning the necessary skills to connect with clarity and conciseness. Arguably, sharing knowledge and experience of conserving cultural heritage can only enhance the relevance and significance of the work done and any means to enrich this narrative is positive.

1.5 A Reality Check

Finally, a dose of...