1 Introduction

1.1 From carrier conservation to content preservation

A substantial change of paradigm in audiovisual preservation began as early as 25 years ago. Until then, audio and video preservation followed the traditional pattern that is still valid for archives of text documents and museums around the world: To safeguard the objects placed in their care.

Around 1990, however, audio archivists began to realise that following this principle would ultimately be in vain. It was becoming obvious — and this is the topic of this publication — that audio and video carriers are vulnerable. Most are unstable when compared with the great majority of text documents. Moreover, being machine-readable documents, the availability of replay equipment was equally important for the retrieval of their contents as carrier integrity.

By that time, it was also becoming obvious that the digital technologies and the enormous pace of technical innovation was creating new formats in an ever faster sequence and, therefore, with ever shorter life cycles. This would confront archivists with the additional challenge of keeping the format specific replay equipment for an ever-growing number of formats in operable condition.

This led to the change of paradigm: Safeguard the content, not the original carrier, was the new mantra. This is achieved by copying the contents from one preservation platform to the next. In order to avoid copying losses, copying has to be done in the digital domain. Analogue contents have, therefore, to be digitised and, together with pre-IT digital contents, converted into files. These will be safeguarded like all other computer files by adequately equipped and managed digital repositories.

While in its beginnings this new paradigm was not accepted without dispute, it was widely adopted for audio archiving from the early 1990s onward and was accepted soon after by video archivists. Meanwhile, because of the global change from analogue to digital film projection and the retreat of the industry from the production of analogue film, this principle is now also widely applied in film preservation.

1.2 IASA’s role

IASA members have been active players in this process, and IASA as an organisation has always provided an open platform for this development. As a consequence, this principle has been codified as a standard by the IASA Technical Committee in The Safeguarding of the Audio Heritage: Ethics, Principles and Preservation Strategy, colloquially referred to as IASA-TC 03. This is now in its third version and available in eight languages. The message, in a nutshell, is:

Long-term preservation of audio (and implicitly also for video) can only be achieved by converting contents into files, and by maintaining these files like any other computer data.

Consequently, after codification of the principle, in 2004 IASA published IASA-TC 04, Production and Preservation of Digital Audio Objects, and is preparing IASA-TC 06, Production and Preservation of Digital Video Objects.

More information about these publications can be found on the IASA website at http://www.iasa-web.org/iasa-publications.

1.3 The rationale for this publication

Why does IASA now publish this document at the end of the era of traditional audiovisual carriers?

It is true that a considerable part of the worldwide audio and video holdings1—typically those owned by broadcasting and national archives of wealthy countries—have already been digitised, or are on their way to being digitised for long-term preservation. Although the new methodology of audiovisual long-term preservation had been universally accepted by the end of the 20th century, there remains a considerable part of the audiovisual legacy that is still stored on its original carriers. The main reason is obviously the lack of funds. But also lacking is a sense of urgency to complete the digitisation of content.

There is an ever-decreasing time window to complete the digitisation process before the small pool of equipment in operable condition required for the replay of traditional formats vanishes. Today, this window is estimated to be between 10 to 15 years2, which makes the provision of optimal storage conditions imperative. This is particularly important for archives in hot and humid climatic zones. The purpose of this publication is to assist stakeholders to optimise storage conditions as an interim measure before professional longterm preservation through digitisation can be funded and organised.

Additionally, optimisation of life expectancy assists the archive to follow the recommendations of IASA-TC 03 to keep the originals in good storage after digitisation as a safeguard against technical advances making better copies possible.

Under no circumstances, however, must these guidelines be misunderstood as being a complete solution. It is dangerous to assume that conventional conservation (passive preservation) may be a viable method for achieving the long-term preservation of, for example, a mixed media collection. Inevitably, deterioration will progress and will ultimately limit the retrievability of stored signals. An even greater threat is the increasing difficulty of obtaining working replay equipment and spare parts to keep machines operating. For several tapebased formats, the shortage of replay equipment is already very severe. Sooner or later, even the most carefully preserved carriers will become totally unplayable. Active preservation by following IASA-TC 03 and TC 04 is absolutely imperative.

1. The world-wide archival holdings of audio and video carriers have been roughly estimated to amount to 200 million hours. This estimate, however, includes multiple copies.

2. On average, for magnetic tape based documents this time window may be even shorter, for mechanical and optical carriers probably longer.

1.4 Content, organisation, bibliography and citations

TC 05 concentrates on measures to optimise conditions for the preservation of physical and chemical integrity of traditional, haptic audio and video carriers. It concentrates on those carriers of recording systems that have been accepted by the market, and form 99% (or more) of all audio and video collections. It is not a handbook of audiovisual recording systems. Therefore, it does not discuss the vast variety of instantaneous audio discs, or rarely used recordings systems like magnetic wire or steel tape, Philips-Miller, Selenophone, etc., and mechanical video discs such as TED. The mainstream recording systems, however, are explained to some degree, in order to provide a basic understanding of the specific function and features of carriers: why and how handling and storage could negatively or positively influence their physical and chemical integrity, and what influence damage and/or deterioration processes would have on signal retrieval.

TC 05 is not a catalogue of mere Dos and Don’ts. Optimal preservation measures are always a compromise between many, often conflicting parameters, superimposed by the individual situation of a collection in terms of climatic conditions, the available premises, personnel, and the financial situation. No meaningful advice can be given for all possible situations. TC 05 explains the principal problems and provides a basis for the archivist to take a responsible decision in accordance with a specific situation. This is the reason why, for example, climatic storage ranges are recommended rather than strict figures, which often trigger a false feeling of security, whereas each chosen value is only a compromise. This is also the reason why TC 05 does not provide a general “Code of Practice”, as this would hardly fit the diversity of structures, contents, tasks, environmental and financial circumstances of collections. However, archives are strongly encouraged to develop and codify, within the limits of physical and chemical constraints, their specific rules of procedures.3

This set of guidelines is broadly divided into two main parts. The first part (Section 2), explains the main types of audio and video carriers, their composition and recording principles, physical and chemical stability, and deterioration caused by normal replay.

The second part (Sections 3–5), advises on best practice for passive preservation through careful handling and appropriate storage and transport conditions.

It should, finally, be noted that cleaning and restoration of carriers is not part of this publication. These aspects are part of signal extraction and discussed in IASA-TC 04, chapter 5. The bibliography lists books and articles, including electronic information, which have become the “mainstream” of audiovisual preservation literature. Generally, the information and recommendations of this publication that are based on common and undisputed knowledge are not specifically referenced. However, references are given when — because of new experiences or information, or research — new recommendations are made or deviations from the mainstream of earlier recommendations are suggested. In addition, it should be noted that this book also contains primary source information: observations and appraisals based on the experiences of the authors gathered over years and decades.

As these guidelines concentrate on handling and storage, there is generally no discussion of variants and discrepancies between publications concerning composition and/ or deterioration of materials.

Cross-references to IASA-TC 04 are made to the second edition (2009) of these guidelines.

3. The British Library National Sound Archive Code of Principles may serve as a structural example. In A.Ward 1990, Appendix 1.

1.5 Responsibility

This is a publication within the series of the IASA Technical Committee: Standards, Recommended Practices and Strategies.

Contributing authors are the following TC members:

George Boston
Kevin Bradley
Mike Casey
Stefano Cavaglieri
ean Marc Fontaine
Lars Gaustad
Albrecht Häfner
Stig-Lennard Molneryd
Richard Ranft
Dietrich Schüller
Nadja Wallaszkovits

and the guest authors

Friedrich Engel
Patrick Feaster
Sebastian Gabler

Unless otherwise quoted: Technical drawings are by Albrecht Häfner, photographs by Dietrich Schüller and Nadja Wallaszkovits.

The publication was reviewed by the IASA Technical Committee.

This text has been composed and checked with great diligence. It represents today’s knowledge and the present foresight of risks. However, the great variety of materials, and of concrete environmental and handling factors may require individual solutions, for which this text is aimed as a general guideline. Many aspects determining the physical and chemical stability of carriers and their components are yet not fully understood. Therefore, neither the editors, the authors, the Technical Committee, nor IASA as an association may be held responsible for any damage or loss which might be ascribed to the recommendations or opinions expressed in text.

The editors would be indebted for comments on possible omissions, mistakes, or new development or experiences that may shed new light onto the recommendations given.

English language editing was in the hands of George Boston. As many readers of this document will be non-native English speakers, simplicity of expression was the aim. Like the other IASA-TC publications, orthography follows UK rules.

Cooperative publications involving experts actively engaged in their daily professional lives are a challenging task. Consequently, the completion of these guidelines took longer than originally expected. The editors would like to express their gratitude to the contributors for their input, the Technical Committee for its review and support, IASA Editors Bertram Lyons and Richard Ranft for their assistance and substantial efforts in converting the manuscript into print and web editions, and, eventually, the IASA Board, IASA members and other readers for their patience in waiting for its completion.

Dietrich Schüller
Albrecht Häfner
September 2014