Videotape was manufactured for short-term production use, not as an archival medium for the long-term. Information about risks to videotape is largely anecdotal; very few controlled studies have been done. Dr. John W.C. Van Bogart, in the 1995 publication "Magnetic Tape Storage and Handling: A Guide for Libraries and Archives," estimates a maximum life expectancy of thirty years for magnetic tape. In practice, useful shelf life depends on such variables as tape format and/or brand, storage conditions, number of recordings, tape handling, and conditions of playback. Periodic condition assessments and conservation actions can help slow deterioration and improve the chances of having viable information once an older tape is transferred to a contemporary format.
Below are basic descriptions of common risks; for more information, consult Resources and Sources.
Equipment obsolescence
Common chemical deterioration
Mold
Mechanical damage
Improper care and handling
Unintended recording
Magnetic fields
Unwise decisions about duplication
Inadequate description or documentation
Equipment and media obsolescence and fragility
Since videotape is dependent on playback equipment to be seen and heard, the loss of this equipment creates the greatest risk. Format identification will help you establish whether playback equipment is available for tapes in your collection. For example, some formats, such as 2" quadruplex, have been obsolete for over 25 years, so equipment, parts, and experienced technicians for formats are difficult to find. Some tape formats require specific machines to playback properly; for example, not all 3/4" Umatic tapes will play back on the same Umatic deck. The media or tape formats are also changing. One only needs to remember laser disks - marketed as a revolutionary new format - as a recent example of media obsolescence.
Machines that play back small tape formats are not considered durable; the same can be said about the tapes themselves. Formats such as 8mm and Hi8 fall into this category - thin tape in a tiny container. In addition, small decks, developed for the consumer or "pro-sumer" market, are difficult to work on, considered more consumable, and often expensive to repair relative to their original value.
Common chemical deterioration
Simply speaking, most videotape is composed of iron oxide particles imbedded in a binder on a base film of polyester terepthalate (PET). The binder is actually composed of a number of different substances, the primary one being polyester polyurethane - but different tape manufacturers created different formulations. These different formulations make some tapes more susceptible to deterioration than others.
The most common problem with videotape deterioration is sticky shed syndrome, where the binder absorbs moisture and undergoes chemical changes through a process called hydrolysis. These changes cause the binder and magnetic particles to become sticky and to detach, or shed, from the base film. When these substances are shed during playback, the machine can stop playing altogether.
Some older tapes may be found to have an acetate base. Acetate is subject to vinegar syndrome, where the base decomposes and creates acidic acid. High temperatures hasten the process of deterioration, whether vinegar syndrome or sticky shed syndrome. Cool, dry storage will slow chemical deterioration.
Newer tapes have different problems. For example, "metal evaporated" tapes, common in small formats like Hi8, have been seen to have corrosion problems, leading to a different type of metal oxide "shedding" with the same result - the loss of oxides leads to signal loss. See risks associated with particular formats in the format identification section.
Mold
Humid, warm conditions can promote the growth of mold on tape surfaces. Moldy tapes will require specialized handling and cleaning. Since mold can be toxic, care should be taken during tape inspection.
Mechanical damage
damaged tape
Improper care and handling
poor tape pack
Poor housing also creates a risk for videotape. Paperboard tape cases create dust as they deteriorate, and paper materials tend to hold moisture and become more acidic with time. Tapes without cases obviously have no protection from particulate matter.
tape down ends of open reels
Tapes that are not re-wound after use, or those that are stacked horizontally instead of stored on edge, are subject to pack problems. Overtime, the tape pack can become uneven, exposing tape edges to possible damage, and making playback more difficult. Important information is held near the edges of magnetic tape. In the case of open reel tapes, those not taped down at the end will become loose over time. These loose ends tend to fold over or deform. Loose tapes are also more susceptible to dirt and dust entering the tape pack.
Unintended recording
3/4" U-Matic in protected mode
Magnetic fields
A tape's signal (the information carrier) is represented on a tape by the arrangement of the magnetic particles into a particular pattern. Strong magnetic fields can affect the signal on a tape, causing it to become unreadable or adding to errors in playback. Common mistakes include leaving tapes on top of, or next to, a television, computer monitor, speaker, or microphone. Motors, transformers, generators, and industrial cleaning equipment are other devices that can cause demagnetization if a tape is within close proximity.
In recent years, there has been more discussion about transporting videotapes through airport security. It has been reported that airport scanning devices for checked baggage are damaging to videotapes. Biological decontamination devices are also reported to be damaging. Should these risks apply in the work of your organization, it is recommended that you keep current on these topics such through AMIA-L, the listserv of the Association of Moving Image Archivists.
Unwise decisions about duplication
Videotapes often exist in multiples; many copies may be made from a single edit master or original recording. Several different organizations may hold the same works in different formats, in different generations, and the tapes may be in different conditions. An artist/producer may retain an original or master on professional stock such as BetacamSP, while an organization holds a viewing copy on a lower quality format such as VHS.
The image quality of an analog tape degrades each time a copy is made. Although digital tape copies are called "clones," errors may occur as tapes are transferred, causing artifacts, or image distortions. If an inferior tape is re-mastered, or the preservation process is unprofessional, the result may be a version that is substantially degraded, and substantially altered from the artist/producer's original work.
Inadequate description or documentation
labels may be loose in cases