CoPAR Bulletin 13: Preserving Audio-Visual Materials on Magnetic Tape
Preserving Audio-Visual Materials on Magnetic Tape
by Willow Roberts Powers
Audio tapes and videos are important elements of anthropological archives. Audio tape has changed formats with changing technology. Videotape is becoming increasingly important in documentation. These are fragile items with relatively short life-spans in archival terms, although research is ongoing to test and improve these materials for archival purposes. To keep abreast of current findings, check reputable sources of information (see References at the end of this bulletin) or talk to a bona fide archivist who specializes in preservation of magnetic media.
Older recording equipment includes wax cylinders and wire recorders. These special formats require careful, expert, conservation; contact a museum or archival conservator for advice.
Magnetic media: general information
Magnetic media was first used in recording sound in 1935; it is now also used to record images. All the materials are synthetic substances: life-span is relatively short, between 10-20 years for digital magnetic tape. Environment – smoke and pollution, heat, sunlight, other magnetic fields, fluctuation of temperature, high humidity – and constant use both contribute to deterioration. Extensive use or poor conditions can severely shorten the life of a tape to as little as one year.
Magnetic tape – audio tapes, video tapes, cartridges – consists of a polyester base, a binder (usually some form of polyurethane) and metal oxide particles, which are magnetized, held in the binder. Each of these three elements can deteriorate differently. The layers of the tape may deteriorate or flake off; friction from deteriorating tape can result in failure of the tape to feed through the machine. The equipment can also cause problems, such as build up on the head, resulting in signal failure.
Technology continues to contribute to quality and longevity of tape, and to change recording devices and formats, producing products that last better, as well as new products with unknown shelf life. Equipment also changes along with the tape medium, with the result that a specific tape may be in good condition but cannot be played for lack of the right equipment.
For additional technical information, the Commission on Preservation and Access and the National Media Laboratory publish extensive details on magnetic tape, its composition, storage, handling, and problems, online at http://www.clir.org/pubs/reports.
Basic Information, all magnetic media
Store in a cool, dry, dark place — the cooler the better.
Keep away from light.
Keep away from cigarette smoke, wood-burning stoves or fireplaces.
Keep away from heat; never keep magnetic tapes for even short periods of time in summer in automobiles or any other hot, enclosed space.
Keep away from other magnetic sources (such as telephones, motors in equipment).
Rewind, carefully, at least once every three years.
Do not use magnetic media cleaners very often.
In case of disasters or damage, contact a professional for advice (see Resources).
Types of tape: Magnetic tape, subject to deterioration
- Record on new tapes from well-known companies using 60 minute tapes only. The longer the tape, the less sturdy the tape base.
- Make several high quality copies: a master, a reference copy, and a use copy. This is especially necessary for transcription (stopping and pausing weakens the tape base).
- Plan to rerecord as technology advances and improves, but keep abreast of the information about new media. Keep old tapes.
- Store in a cool, dark, dry area
- Store away from high humidity, sources of damp, or any storage area near water pipes or any other water source where flooding (however unlikely) is possible.
- Store away from smoke (cigarette smoke, wood-burning stoves or fireplaces, etc.)
- Store far from heat and all sources of heat, including equipment, machinery, sunlight, closed automobiles, etc.
- Keep away from magnetic fields such as telephones or machine motors.
- Store tapes in cases. The best cases are made from inert, somewhat flexible polyester, which does not crack or break, obtained from archival suppliers. At least keep in the original case.
- Store in boxes in a clean, cool, dark, dry area.
- Rewind carefully and slowly from time to time (about once every three years).
- Treat carefully, and use in well-maintained equipment. Clean heads of tape recorders from time to time. Tapes used in poor machines (automobile tape players, for example) run a high risk of catching, breaking, or tearing.
- Transcribe and print all critical interviews or other important recorded data, on acid free paper; this will save the use of tapes in constant replay of small sections (as well as making comparison easier). Archival paper is known to last 100 years at least; audio tape life is still an unknown property.
- Always document all tapes with as much information as is relevant. Basic data should be included: date, name(s), name of interviewer/recorder, project or topic, tape number and side, etc.
- Document each version (master, reference, and use copy) and label accordingly.
- Create a list with more extensive documentation which will cross reference to the tape
- Make sure the permission form(s) for each tape is (are) filed and cross referenced for every tape.
- If copies of tapes have been given to others, especially those recorded on the tape, it is useful to note this in the documentation.
Basic Facts: Videotape consists of a polyester base, a binder (usually some form of polyurethane) and metal oxide particles, which are magnetized, held in the binder. Each of these three elements can deteriorate. Video life is very short, from 10 years to a possible 30 years (a more conservative estimate is 20 years).
The following practices for video documentation will contribute to longevity.
- Use new tape from a recognized company. Do not re-use video tapes if you want to make tapes that last.
- Use 1/2″ Betacam format.
- Use 60 minute, not extended-play, videos. The tape base is less sturdy in longer tapes.
- Always make at least 2 copies: an archival master and a use copy. However, it is even better to make 3 copies: a master, a reference copy, and a use copy. Any duplication can be made from the reference copy, which will otherwise not be used.
- Copy all important video material immediately. Make sure the master is not ever played.
- Fast-forward contributes to rapid deterioration.
- Rewind carefully at least once a year.
- Document all tapes so they do not need to be played unnecessarily.
- When playing tapes, make sure the equipment is operating properly; malfunctioning or dirty equipment will cause damage.
- Do not leave the tape in the video recorder for a long time, such as overnight.
- Do not eject a tape in the middle of a recording.
- Pausing a tape for a long time can also contribute to poor image quality.
- Treat carefully – do not drop or damage the casing; do not mail originals. If mailing copies, wrap well in bubble wrap or other insulating and shock-proof wrapping.
- Keep informed about technical improvements and new materials; plan to re-record (every decade is the current thinking), but retain older tapes.
- Do not store video tapes flat; store videos on end, just like a book on a shelf.
- Keep in a clean, cool, dark, dry area—the colder the better. Heat will seriously curtail their life-span, as will cigarette smoke, light, and moisture. Heat can also cause permanent damage.
- Store in plastic cases, upright inside lidded cardboard boxes. (Archival catalogues carry video cases and storage boxes.)
- Videos usually come with labels, usually on the spine, which are essential. Additional labels may be put on the flat side surface. (Archival catalogues listed in CoPAR Bulletin No.11 carry labels in all sizes and shapes with special backings that last longer.)
- Label every tape with all basic data.
- Make a record (a list, or a record for every tape) that fully documents each video.
- Make sure the permission form(s) are available, and cross-referenced with the video.
- Transcribe important data, to ensure a life span beyond 20 years. Or, copy each important video every ten years.
Compact Discs (CDs)
Basic Facts: CDs are made of a variety of materials in layers. The base or substrate has signals etched by laser. They have a short life, archivally speaking, from 20 to 30 years. The information they contain tends to be stable, that is until the disc itself fails or is damaged, and can be copied without loss.
- Use good quality CDs
- Don’t use them for long term storage of information; reformat the information regularly.
- Don’t try to remove a label that has already been put on them.
- Don’t store near acidic materials (cardboard, paper, etc).
- Reformatting is essential to keep up with software changes, media technology, new materials. This will require future planning and the means to obtain the best information from reputable sources.
- Store in Tyvek® sleeves, or, if this is not possible, store in jewel case containers with a tray and/or hub that hold the disk in place.
- Don’t put labels on CDs, or write directly on them in ink or pencil, label the case.
- Store upright; make sure they are supported but not under pressure.
- Keep in a cool, dry, dark place away from smoke.
- Do not store near magnetic sources.
- Check and document the software requirements.
- Label the case rather than the CD.
- Create an inventory.
Backing up work is always essential. Digital preservation, however, requires more than duplication, and will be addressed in a later bulletin (CoPAR Bulletin No. 15). Useful web sites for digital preservation are: PADI (Preserving Access to Digital Information) at http://www.nla.gov.au/padi/; and http://www.arma.org/standards/index.cfm.
References and Resources
Henry Wilhelm, 1993. The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures. Grinnell, Iowa: Preservation Publishing Company. (Includes information on black and white film also)
Web site: http://www.wilhelm-research.com/
Image Permanence Institute
Rochester Institute of Technology
70 Lomb Memorial Drive
Rochester, NY 14623-5604
Web site: http://www.rit.edu
Contact at: email@example.com
Tel: 585-475-7230 or 585-475-5199
Commission on Preservation and Access, and
The National Media Laboratory
St.Paul, MN 55144-1000
Web site: www.clir.org/pubs/reports