Since the late 1950s, video has served as a powerful medium of artistic expression and visual documentation, capturing and portraying events that shape our lives and our perception of the world. Today, video camcorders are used frequently to document momentous events in the life of a family - the birth of a child, high school graduation, summer vacations, and weddings.
Unfortunately, as an information storage medium, videotape is not as stable as photographs. Videotape is a fragile medium subject to damage and deterioration from exposure to poor environmental conditions and inadequate handling practices. Even if properly cared for, magnetic tape may last only for a few decades.

Composition

Videotape is composed primarily of three components:
magnetic (metal oxide) particles, a polyurethane-based binder, and a polyester base material.

The metal oxide particles record and store magnetic signals. Magnetic particles differ greatly in their stability. Changes in the magnetic properties of these materials may result in an irretrievable loss of color, saturation, and sound clarity. Iron oxide and cobalt-modified iron oxide particles are the most stable of the commonly available magnetic materials used in videotapes. These materials are generally found in most grades of commonly available non-professional videotapes.

The polyurethane binder holds the magnetic particles in place. Often the binder also contains special lubricants to smooth passage of the tape across the recording and playback devices. The binder is subject to a type of chemical deterioration known as hydrolysis. In this process, long polymeric molecules are broken apart by a reaction with water to produce shorter and less mechanically stable molecules. As a result, the videotape becomes sticky and soft - magnetic particles may shed from the base (referred to as sticky shed syndrome) and clog recording heads. Playback is impossible.

The polyester base material provides a flexible support. In itself the base is chemically stable. However, the polyester base is susceptible to physical deformations due to excessive tape pack stresses and poor wind quality. These deformations can result in mistracking when the tape is played. A back coating, if present, reduces static electricity and aids in keeping the tape securely wound when in storage. The back coat also serves to reduce tape friction and helps prevent tape distortion by providing a more uniform tape pack wind.

All components are subject to irreversible deterioration caused by exposure to extremes of temperature and humidity as well as physical damage due to poor handling and storage practices.

Environment

The best way to prevent deterioration is to store all videotapes in an environment that does not fluctuate significantly in temperature or relative humidity. High temperature, high humidity, and the presence of dust and pollutants in the air will result in irreversible loss of both video and audio signals.

A dust-free, temperature and humidity controlled environment - 68 degrees F and 20-30% relative humidity is recommended for the safe home storage of videotape.

Never keep videotapes in a hot, wet environment. Do not expose them to direct sunlight, which will cause them to heat up and will warp the reels or cassette housing. Storage at high temperatures (in an attic or on windowsills) may result in tape-to-tape adhesion (known as blocking), degradation of the binder (known as shedding), and permanent distortion of the tape backing. Such degradations can lead to severe image deterioration known as dropouts. In video recordings, short-duration dropouts appear as flashes, white spots, or streaks. Storage at high humidity (in a basement or garage) may cause fungal growth.

Handling

Minimize tape handling at all times. Take care not to drop tapes or cassettes. Do not touch the surface or the edge of the tape.

Avoid contamination of the tape by dirt, dust, food, cigarette smoke, and airborne pollutants. Cleanliness is important because minute debris can cause loss of signal or dropouts. The frequent appearance of dropouts is an indication that the videotape playback device is contaminated with dirt and/or that the tape is deteriorating.

Videotapes, especially modern ones, are recorded with high levels of magnetic energy that make them relatively immune to problems from common household magnetic fields. Weak magnetic fields are produced around electrical appliances, power tools, and television sets. However it is good practice to avoid exposing tapes to any magnetic fields. A few feet separation from a magnetic source will usually provide sufficient protection. Airport walk-through metal detectors and x-ray machines are probably safe, but hand inspection by airport security personnel will ensure an extra level of protection.

Storage

When tapes are not in use, store them on end (like books on a library shelf) to prevent deformation. Do not store videotapes lying flat. When housed in a horizontal position, pressure from other tapes can cause distortions. Rewind tapes after recording or playback.

A tape must not be left threaded in the video recorder for a long period. Leaving a tape in the playback machinery overnight, for example, is not desirable. Likewise, tapes should be inserted and ejected only at blank, unrecorded sections. Never eject a tape in the middle of a recording. Pausing tapes for prolonged periods also results in degraded image quality. After recording, rewind the tape before ejecting it.

Always return tapes to carefully labelled protective inert plastic containers when they are not in use. Cardboard boxes deteriorate over time and provide little protection from handling, environmental fluctuations, fire, or water.

Playback Devices

Playback devices must be cared for and cleaned regularly following recommended maintenance procedures. Protect VCRs with a dust cover. Dirt in the tape path through the machine can permanently scratch the videotape's surface.

Recording Practices

Always use a new, brand-name tape from a recognized manufacturer for important recordings. Avoid extended-play tapes because they use a thinner polyester tape base and, therefore, are less wear resistant. Before recording it is good practice to wind the tape from one hub to another and then back. This procedure will relieve stresses on the tape that could result in a slightly irregular passage of the tape through the recorder. Record at standard speed. Always break off the tab on a videocassette to prevent accidental re-record. Make protection copies of the most valuable videotapes and keep them in a separate location.

Disaster Situations

When disaster strikes, it can leave a single tape or an entire collection unusable. For this reason, videotapes must be well protected from damage by fire or water. Magnetic tape cannot tolerate high temperatures. Temperatures above 150 degrees F can cause permanent damage to videotape. In the unfortunate event of a disaster, experience, research, and testing have led to the development of highly effective restoration and remastering techniques that may preserve lost or damaged information.

Restoration and Conservation

Deteriorated tapes may require duplication onto a new tape stock (called reformatting). This is especially true if the original recording was done on a type of machine that is no longer in production (like Sony Betamax). Tapes that are ten years old or older or that have been poorly stored and improperly handled are a high priority for restoration. Restoration is the process by which a videotape, degraded by age, is temporarily or permanently transcribed to a playable condition. The restoration process usually requires highly technical methods and materials.

Getting Help

Professional conservators are skilled in many of the preventive preservation techniques that can prolong the life of your videotape. Conservators will also provide information on restoration and conservation services that may be required for videotapes that are severely damaged or obsolete.

Further Reading and Resources

Boyle, Deirdre. Video Preservation: Securing the Future of the Past. New York: Media Alliance, 1993 (Media Alliance, c/o Thirteen/WNET, 356 W. 58th St., New York, NY 10019)

Van Bogart, John. Magnetic Tape Storage and Handling: A Guide for Libraries and Archives. Washington, DC: National Media Lab and Commission on Preservation and Access, 1995. (Commission on Preservation and Access, 1755 Mass. Ave., NW, Ste. 500, Washington, DC 20036; http://www.clir.org

Association of Moving Image Archivists
c/o National Center for Film and Video Preservation
P.O. Box 27999
2021 N. Western Ave.
Los Angeles, CA 90027

National Media Lab
P.O. Box 33015
St. Paul, MN 55133 - 3015
http://www.nml.org

National Archives and Records Administration
Motion Picture Sound and Video Branch
8601 Adelphi Rd.
College Park, MD 20740 - 6001

Library of Congress
Motion Picture Broadcasting and
Recorded Sound Division
Washington, DC 20540-4500
http://lcweb.loc.gov/

This information is provided courtesy of the American Institute for Conservation of Historic and Artistic Works (AIC), the national membership organization of conservation professionals dedicated to preserving the art and historic artifacts of our cultural heritage for future generations. Among other services of the AIC is the Guide to Conservation Services, which provides a free list of conservators in your geographic region. The AIC brochure Guidelines for Selecting a Conservator, will help you make an informed choice.

The recommendations in this brochure are intended as guidance only, and AIC does not assume responsibility or liability.

Prepared by Debbie Hess Norris with assistance from Peter Adelstein, Deirdre Boyle, Connie Brooks, Alan Lewis, Jim Lindner and Paul Messier, 1997

http://aic.stanford.edu/