Studies in Archaeological Conservation

Chris Caple, Vicky Garlick, Chris Caple, Vicky Garlick

• Publisher: Routledge
• Year: 2020
• Print ISBN: 9780367358440
• eBook ISBN: 9781000223514
• Edition: 1
• Topic: Art
• Subtopic: Art General

Studies in Archaeological Conservation features a range of case studies that explore the techniques and approaches used in current conservation practice around the world and, taken together, provide a picture of present practice in some of the world-leading museums and heritage organisations.

Archaeological excavations produce thousands of corroded and degraded fragments of metal, ceramic, and organic material that are transformed by archaeological conservators into the beautiful and informative objects that fill the cases of museums. The knowledge and expertise required to undertake this transformation is demonstrated within this book in a series of 26 fascinating case studies in archaeological conservation and artefact investigation, undertaken in laboratories around the world. These case studies are contextualised by a detailed introductory chapter, which explores the challenges presented by researching and conserving archaeological artefacts and details how the case studies illustrate the current state of the subject.

Studies in Archaeological Conservation is the first book for over a quarter of a century to show the range and diversity of archaeological conservation, in this case through a series of case studies. As a result, the book will be of great interest to practising conservators, conservation students, and archaeologists around the world.

PART I

Introduction

1

INTRODUCTION

The challenges of archaeological conservation

Chris Caple

The nature of archaeological artefacts

Archaeological artefacts¹ can be defined as those objects of the past which have been recovered from the ground, normally by archaeological excavation; a technical process which unearths and records artefacts, structures, and soil features in their stratigraphic sequence. Archaeological research correlates the objects, structures, and soil features with known examples to determine what activities took place on the sites and fit this evidence into the existing sequence of material culture and historically recorded events which define the human past.² The artefacts recovered, as well as human remains and associated structures, are not simply archaeological evidence; they may also be ancient relics venerated by different peoples of the present. Consequently, the artefacts have a duality as part of an investigative, knowledge-producing process (archaeology) and as material culture which has significance to a wider public, often defining their tribal/regional, national, and religious identity.

The care and repair of venerated ancient artefacts which have had a symbolic and educational (museum) role, rather than a function dictated by their form and original use, are attested as early as the Roman and Greek period (Strong 1973). However, the conservation of archaeological artefacts we practice today (ICON 2020)³ has a clearly identifiable foundation in the 19th-century activities of antiquarians cleaning objects from their excavations with carborundum and vinegar and the scientific enquiries of such scientists as Sir Humphrey Davy (Caple 2000: 50–55). Although we might occasionally consider the 19th-century treatment of artefacts as inadequate or even cavalier, judgements about the past using the ethical standards and knowledge of the present demonstrate a fundamental lack of understanding about the past. For them it was essential to see the shape and decoration of the object in order to construct the earliest artefact typologies, which were often their only means of dating. The cleaning and conservation work undertaken in the 18th and 19th centuries describe the level of knowledge, the availability of resources, and the value which ancient artefacts had for that society. In the same way, the conservation processes described in the following case studies represent the state of knowledge, the resources available, and the public expectations of museum objects in the opening decades of the 21st century.

Archaeological artefacts come with a range of challenging attributes (Figure 1.1). Unlike objects in museum collections, which are already regarded as worthy of study and preservation, archaeological excavations produce numerous fragments and corroded lumps covered in soil which may or may not be objects, and may or may not have value (Caple and Garlick 2018).

FIGURE 1.1Attributes of artefacts from archaeological excavation

Source: Chris Caple

The conservation process

The archaeological process transforms the physical evidence of the past into knowledge which is normally articulated in written and image form. In unearthing the past, archaeology largely destroys it. Often, the only parts of the archaeological process to survive are the recovered artefacts, and even these are not stable. Obscured by decay products and soil, they require a conservator to investigate, reveal, and preserve the object (Caple 2000: 33–35). Once retrieved from archaeological sites, the steps involved in the archaeological conservation process, Figure 1.2, start with a full appreciation of the object, including detailed recording, analysis of the materials, and researching the object. This leads to an understanding of the way in which the object was created and used, and the values it has for people in both the past and the present.⁴ A statement of significance can usefully be created which encapsulates this. The decay processes affecting the object and desired aims of any conservation process are also clearly identified at this point in the process. Conservation can often be the only point at which the archaeological artefact is examined (and recorded) in detail (Cronyn 1990: 9).

FIGURE 1.2Flowchart of the typical conservation process, emphasising the points of output. Through the conservation record, information is abstracted to inform the finds of researcher/archaeologist and future conservators. Through the display of the completed object, the museum informs the public, whilst the stored object is available for future study

Source: Chris Caple

The conservation process invariably seeks to transform an unstable and unreadable object into a stable information source. If interventive (remedial) conservation processes such as cleaning and stabilisation are not appropriate, objects may be recorded, assessed, and researched and preventive measures such as suitable storage undertaken to preserve them in the long term. It is important not to see conservation simply in terms of the object's present appearance, but to recognise it as a process, creating and preserving an information source which recognises and preserves values beyond physical appearance. Increasing the information known about an object can, for example, increase its value to the point where preserving the remains are justified (Caple 1999).

The capacity to successfully conserve an object depends on the skills and knowledge of the conservator. In some instances there may be very little published information to aid the conservator (Chapter 20). Frequently, conservation literature focuses on new developments presented at conferences or published in journals; there is little published on actual practices. In the absence of published details, and given the differing nature of artefacts, conservators routinely experiment with different treatments and materials in order to achieve the greatest benefit for the object with least risk to the artefact, conservator, and viewing public. It remains challenging to employ good experimental technique so that only a single variable is altered and a true comparison between differing materials and techniques is made (Chapters 12, 19, and 20). Even with such information, making the appropriate balanced decision, especially when faced with artefacts composed of several materials which require different treatments and storage conditions, can be problematic. Exercising professional judgement using the relative evidential value and pragmatic consideration of the robustness and rarity of materials leads to an informed decision (Chapters 18 and 25).

Whilst it may be appropriate to undertake differing amounts of conservation work on artefacts, the quality of the work should always remain as high as possible. Given finite resources, standardised batch treatments may be appropriate for dealing with large volumes of archaeological material (Pye 2001: 132).

Archaeological conservators receiving material from excavations are responsible for aiding and informing the archaeological process as well as conserving any artefacts that are considered worthy of becoming part of permanent collections and/or the archaeological record. The conservator's responsibility in the archaeological process requires assessment (investigation and identification) and selection of the objects for retention and conservation from this excavated material. This is normally achieved by collaborating with colleagues such as archaeologists and finds researchers (Cronyn 1990: 10–13). The archaeological conservator is part of the team which turns physical remains into knowledge. Excavators recover the object; conservators clean, reveal, and stabilise; illustrators and photographers capture the cleaned object; finds researchers identify the objects; and archaeologists pull all the information into a coherent explanation of the past. However, where teams are smaller, conservators may find themselves recording the object and undertaking finds research. Consequently, it is important that the archaeological conservator has a clear appreciation of the whole process and develops the skills, where necessary, to undertake all these tasks.

It has been argued that conservation is a balance of revelation (cleaning and restoration), investigation, and preservation activities (Caple 2000: 3–35). In the case of archaeological artefacts, there is a particular emphasis on preservation resulting from their value as scarce evidence of the past. In recent years, the abundance of images, replicas, 3D printers, and heavily restored objects has increased the value of many older genuine objects from regimental, religious, art history, textile, social history, and transport history collections as evidence of the past. Consequently, there is a greater emphasis on their preservation (Chapters 12 and 23), and they are increasingly treated as archaeological artefacts.

The organisation of archaeological conservation in practice

Although an object's individual attributes determine the nature and level of conservation it receives, the needs of the collecting institution also impact the extent and emphasis of the conservation work carried out and the conservator's role in the process. Institutions which impact the organisation of archaeological conservation generally fall into three categories:

• Museum collections: Large number of complete objects which primarily have a display and education function. The objects usually already have a known date, culture and function, consequently, conservation work focuses on cleaning, reassembly and restoration of the artefacts for display. In large museums, conservators may work in specialist collection areas and develop considerable skills dealing with specific materials. In smaller museums, a single conservator may work on a range of materials and so requires a more varied range of skills and experiences.
• Large-scale research excavations: These invariably take place on sites of a known date and aim to solve research questions and reveal remains for future display. They unearth objects, which have, through their stratigraphy and associations with other objects and structures, the potential to contribute to our understanding of the past. This information may change the existing perceptions about the date, cultural associations, and use of specific objects. Such high potential archaeological (evidential) value (as well as the fragility and instability of the objects) justifies the costly presence of a conservator on large excavations. Typically, conservators on excavations need the skills to deal with a wide range of materials, especially in on-site conditions. Familiarity with the archaeological process is important.
• Cultural resource management: In countries with commercial archaeology organisations, there are often many small excavations ahead of development; the date, extent, and nature of the site is often initially unknown. The number of artefacts unearthed and their archaeological value, which depend on the stratigraphy, structures, and associations, will often not be known until after the excavation has been completed. In such circumstances, heritage agencies normally build in an assessment phase, where the excavation records, excavated artefacts, historical information, etc. are assessed, and the level of post-excavation resources assigned depends on the assessed value.⁵ This means that the archaeological conservator normally undertakes a large volume of initial assessment work, e.g. X-radiography, packaging, and storage of a large quantity of freshly excavated material, and only undertakes conservation work on a selected group of o...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Dedication
• Contents
• Figures
• Contributors
• Preface
• Acknowledgements
• PART I Introduction
• PART II Case studies: stone and plaster
• PART III Ceramics and glass
• PART IV Metals
• PART V Organics – wood, textiles, leather
• PART VI Bone, composites and display
• Index