Conservation and preservation of electronic media, Conservation and preservation of digital media, Conservation and preservation of magnetic disks, magnetic tapes and optical disks, Reformatting electronic media

Caring for... > Care and preservation of removable digital and electronic media

Digital and electronic technology is, these days, in a state of constant change. Tried and tested products are soon replaced by smaller faster varieties, sometimes with a life span of five years or less. Given the inevitable obsolescence of many digital and electronic products, you need to follow basic preservation guidance to ensure long-term access to information.
This guidance note provides advice on the care, handling, and storage of several of the most commonly used media: flexible magnetic disks, magnetic tapes and optical disks - CD’s and DVD’s.

The main types of removable electronic and digital media
Flexible Magnetic Disks
Generally speaking and as the name implies, these are magnetic disks housed in rigid or semi-rigid casing, usually in 3.5” formats. They have a lifespan of about five years and therefore should not be seen as an appropriate long-term storage option. Larger format 5.25” and 8” formats are now obsolete and any data on these should be copied to more recent media. All flexible magnetic disks are easily damaged and susceptible to accidental erasure and should not be considered as suitable for the long-term preservation of, and access to, data.

Magnetic Tapes
These encompass a range of media comprising two components: a recording layer and the flexible substrate to which it is fixed, usually polyethylene naphthalate. Magnetic tapes are either housed within a cartridge, with one spool, or come in the form of cassettes that have two spools. Two common types are Digital Audio Tape (DAT) - a low capacity variety - Digital Linear Tape and Linear Tape Open are considered the more long-lasting and if stored and handled properly could last at least 30 years. Magnetic tapes on open spools are now considered to be obsolete and should be copied to other media such modern tape cartridges or optical media.

Optical Disks
The most common form of optical disk is the Compact Disc, available in read-only (CD-Rom), recordable (CD-R) and rewriteable (CD-RW). Recordable CDs include a dye layer and a metallic and reflective layer on a clear polycarbonate substrate. Various combinations of these components are available, although sources suggest that CD-Rs with a gold reflective layer and phythalocyanine-based dyes have a longer life span and are the most suitable for long-term preservation.

DVDs (Digital Versatile Discs) were first produced in 1996 and like other forms of optical discs are available as read-only (DVD-ROM), recordable (DVD-R and DVD+R). There are also a number of re-writable formats (DVD-RAM, DVD-RW and DVD+RW). Recordable formats use organic dyes similar to CD-R, although it is difficult to learn exactly what formulations are used. The long-term preservation of DVDs is not well understood, although recommendations for their storage and handling are similar to that for CDs.

What can go wrong
There are two principal reasons why the information contained on your electronic and digital media can become inaccessible: redundancy of the hardware and physical damage to the media itself. The effective lifespan of any electronic or digital storage medium is determined by two factors:

The supporting hardware necessary to read digital and electronic media usually has a shorter life than the media itself. Nevertheless, electronic and digital media is susceptible to damage both through mishandling and inappropriate storage conditions and by storing media in proximity to electromagnetic fields.

Protecting your own collection
Physical protection, careful handling and appropriate storage conditions

General guidance:

Avoid touching the surface; it can easily become scratched. Salt and greasefilms from fingers are equally destructive.

Protect electronic and digital media from liquids and dust, as well as extreme heat or direct sunlight.

Store electronic and digital media vertically in purpose-made storage containers. Rigid containers are preferable to sleeves.

Clean drives routinely to prevent damage to the media; do not keep media in drives though.

Apply labels only to the areas recommended by the manufacturer.

Copying to new formats
To ensure long-term access to your own electronic or digital collections, periodic copying to new formats is well advised.

A conservator can give you advice on best practice and materials for handling, documenting and storing your collection. They can also recommend the best formats and techniques for copying.

Flexible magnetic tape surfaces should not be opened or the tape surface touched.

This article offers general guidance and is not intended to be a substitute for the professional advice of an accredited conservator. The views expressed are those of the author or authors, and do not necessarily represent the views of the Institute of Conservation. The Institute of Conservation would like to acknowledge use of the MGC publication 'Ours for Keeps' in the preparation of this text. The Institute of Conservation and its partners accept no liability for any loss or damage which may arise if this guidance is followed.

The Institute of Conservation would like to acknowledge the support of The Royal Commission for the Exhibition of 1851 in the production of this guidance information. Further information on The Royal Commission for the Exhibition of 1851 and its work is available at www.royalcommission1851.org.uk.