Preservation activities

The aim of the Library’s preservation activities is to lengthen the lifespan of materials. Although the majority of items held in the collections are organic in nature and contain elements which decay, it is possible to slow down this deterioration and ensure their use by future generations.

Environmental controls

Incorrect temperature and relative humidity can have a detrimental effect on collection material. Materials can turn brittle if the conditions are too dry, whereas high humidity can increase the risk of mould growth and pest infestation. Storage and exhibition areas are regularly monitored to ensure that conditions are stable and appropriate for the type of material.

Preventive Cleaning

For health and safety reasons, it's important to ensure that collections are clean and hazard-free for the use of readers and staff. Organic dust and mould spores found on books and archive materials can have an adverse effect on health. The Library undertakes a regular cleaning and storage maintenance program. Items can be acquired by the Library which may be infested with mould growth, insects, dirt and dust. In order to reduce the risk of contaminating the Library’s collections, suspect material is held in a quarantine area, isolated from the rest of the collections. The material is thoroughly cleaned, before being integrated into the Library’s main collections.

Boxes and protective folders

A box creates a microclimate and protects items from damage. The Library has two box making machines which produce bespoke acid-free boxes of archival quality.

Digital preservation

Digital Preservation is a set of activities required to make sure digital objects can be located, rendered, used and understood in the future. This can include managing the object names and locations, updating the storage media, documenting the content and tracking hardware and software changes to make sure digital objects can still be opened and understood.

A digital object is 'an object composed of a set of bit sequences'. A digital object can be either 'born digital' or a 'digital surrogate' which is the result of digitising an analogue or physical object.

Digital objects can take 3 different forms:

• Simple digital objects, which primarily consist of a single file, that is intended to be viewed as one conceptual object, e.g. a Word document or a TIFF image. In some cases they are accompanied by metadata.
• Digital object groups, which consist of a set of independent but related files that have been collectively described, e.g. a floppy disk containing 100 letters. Each file is accessible independently (as a Simple object), but its relationship to other objects in the group provides valuable context.  An example is the photographs of Geoff Charles.
• Complex digital objects, which consist of a group of dependent files that are intended to be viewed as a single conceptual object, e.g. a web site or a CD-ROM.

Issues that affect the ability to preserve and access digital objects include the following:

Technological obsolescence – can affect hardware, software and even the arrangement of the data in a stored file. Some examples of obsolescence include:

• File format is superseded by newer versions, which may no longer be supported by the current vendor or relevant standards body.
• Storage medium may be superseded by newer and denser version of that medium, or by new types of media.
• Device needed to read a storage medium may no longer be manufactured.
• Software used to create, manage or access digital content may be superseded by newer versions.
• Computers are continually being superseded by faster, more powerful machines with more capabilities.

Physical damage/deterioration – can affect hardware and the media carriers on which the digital material is stored. Some examples of physical damage/deterioration include:

• Hardware and media carriers can stop working due to human error, natural events and often just the passing of time.

File formats and Significant Properties

A file format is a particular way to encode information for storage in a computer file. The particular way in which a file format is structured and organized is often laid out in a document called a file format specification. This document provides the details necessary to construct a valid file of a particular type and to develop software applications that can decode and render such files.

Digital objects come in a wide variety of formats but in terms of digital preservation these digital objects need to be widely accepted and generally an open format standard for long-term preservation. The Library therefore takes great care in selecting a file format for preservation and is working on creating guidelines for depositors of accepted and preferred file formats. For images created by the Library as part of its digitisation program the Library currently creates 3 copies of the image - a master TIFF file for preservation purposes and two smaller derivative files, a JPG for the reference or screen display and a GIF for the thumbnail version. In some instances where the resource benefits from zooming capabilities a PFF file is also created.

Significant properties are essential attributes of a digital object that affect its appearance, behaviour, quality and usability. They can be grouped into categories such as:

• content
• context (metadata)
• appearance (e.g. layout, colour)
• behaviour (interaction, functionality)
• structure (e.g. pagination, sections)

Significant properties must be preserved over time for the digital object to remain accessible and meaningful.

The Library’s Digital Preservation Strategy builds upon the existing digital preservation work to continue to enable the long-term sustainability of digital assets, both born digital and digitised, held by the Library.