How long do videotapes last?
We have entrusted our collective memories to be recorded on film or VHS tapes for some forty years, 1956-1996. The ability to record almost every facet our lives in a fixed and tangible form, cheaply and conveniently. Videotapes were never engineered as a permanent record and no professional society recognizes it as a permanent recording medium. Prolonging the life of videotape is a complex task dependent upon many variables, some of which are beyond our control. Well before the years of Smartphones and GoPro’s, the first video recording devices were free-standing boxes about the size of a washer and dryer. The design of these players/recorders transported large open reels of 2-inch-wide magnetic tape that weighed as much as 25 pounds and operated at speeds of 15 inches per second.
The dominant consumer format since the late 1970’s was 1/2 inch VHS, and since 1990 it has had competition from 8mm or Hi-8 formats composed of metal particle or evaporated metal pigments. VHS and Hi-8 nonetheless gave people the opportunity to record the world around them, including the most important events in their lives such as weddings, family vacations, and the occasional unanticipated news event.
- What is the longevity of videotapes?
- What is their basic composition?
- How do videotapes deteriorate or become obsolete?
- Magnetic videotapes and their purpose?
- What’s the chemical stability of videotapes?
- Why use a professional to copy videotapes?
- What are other VHS playback issues?
Longevity of Videotapes
In 1991 Sony’s best estimate of longevity for these materials was about 15 years. 3M indicated that its research was consistent with Sony’s. Maxell declined to predict any life expectancy for its tape products, and a TDK representative indicated he knew of no published data on tape life expectancy by his company, BASF, and that 15 years was a good guess.
Videotapes are layered with products composed of a number of elements. Although the first audio tapes were acetate-based, the underlying support of videotapes consists of:
1). Fairly durable polyester film [Polyethylene Terephthalate (PET)]. A back coating added to professional tapes eases transport through the tape drives and improves overall reliability.
2). Magnetic particles such as iron oxide or chromium dioxide are contained in a polyurethane binder coated to the film substrate.
3). The binder is a complex compound including many elements such as lubricants, dispersing agents, resin-type materials, plasticizers, anti-static agents, protective additives, wetting agents, polymers, and adhesives.
4). The exact chemical formulations are closely guarded secrets which vary from one manufacturer to another.
Moreover, since there are no industry standards for the exact formula of videotapes, the chemical composition of newly manufactured tape is subject to change at any time. With the introduction of digital videotape in 1987, the industry has shifted to a metal particle tape because it can retain far more data than oxide tape.
Deterioration and Obsolescence
Many things can go wrong with videotape that will prevent completely successful playback or, in the worst case, result in catastrophic failure. Causes are often traced to careless or indifferent handling or poorly maintained equipment. These problems, however, pale in comparison to the overarching issues of inherent deterioration and technological obsolescence of video formats and their related equipment. The physical elements that make a videotape vulnerable to deterioration are its physical properties! They consist of organic materials that degrade under the influences of heat, moisture, and pollutant gases.
New formats seem to change every four or five years with a baffling assortment of incompatible options. Given the rate of technological evolution since 1956, a clear consensus exists among archivists and technical experts that the real problem of video preservation is how to cope with technological obsolescence. This phenomenon has reached serious proportions in respect of the copying of 2-inch tapes and open-reel 1/2 inch EIAJ tapes, for which it is already difficult to find and support proper equipment and technicians experienced with these formats.
Magnetic Performance in Videotapes
As stated before, the problems attributed to videotape deterioration are physical and not electronic. Modern magnetic coatings, according to guidance from the 3M Company, can keep the recorded information for an indefinite time unless altered by erasure or re-recording or removed by a magnetic field. The coating’s coercivity or its power to resist demagnetization has steadily increased with implementing new formats. Extreme heat, however, basically from a fire, can demagnetize tape. Magnetic performance is not really an issue under most storage conditions. Factored over many years, however, the particles will begin to demagnetize. Referring to metal particle videotape, one Ampex vice president estimated it would take some 90 years under normal storage conditions before losing sufficient magnetization that would create noticeable degradation.
Chemical Stability of Videotapes
As videotape ages, it begins to break down chemically until it reaches a point where it is no longer capable of using the videotape track for a satisfactory playback and/or transfer to another format. How and when this occurs depend on several factors:
1). Time in storage
2.) Exposure to heat
3.) Atmospheric moisture
4.) Pollutant gases
The earliest videotapes, lacking protective cassette housings, are the most vulnerable to damage and deterioration. The chemical breakdown of videotape binders follow a process called hydrolysis. The binder’s hygroscopic tendency to absorb atmospheric moisture releases acids and alcohol, products or catalysts that accelerate the tape’s destruction. Aged tapes are more hygroscopic than newer tapes. Elevated humidity mixed with warm temperatures accelerates the process while drier and cooler conditions slow it down. Videotapes kept in hot and humid climates have little chance of long-term survival unless placed in carefully controlled storage conditions. Hydrolysis weakens the binder causing oxide shedding, dropouts, and the eventual loss of the tape through severe degradation.
High humidity–besides increasing the rate of moisture absorption and binder deterioration–has other harmful consequences. It can cause further damage by increasing tape pack stresses, distortion, tightness, and dropouts from debris and exudation. High humidity results in clogging, sticky shed syndrome or “stiction,” scoring, and head wear. One tape can contaminate another if machines are not carefully cleaned between plays. In combination with warm temperatures, high humidity will encourage the growth of fungus which attacks the organic compounds in the tape’s binder. Condensation on the tape edge causes “spot hydrolysis,” gluing the edges together and causing the tape to tear if played in this condition without treatment, especially in the newer and thinner tapes.
High temperatures can also cause damage such as increased tape tightness, pressure, distortion, dropouts from wound in debris, layer to layer adhesion, changes in dimensions, all of which promote tracking errors. High temperatures will also have a tendency to separate the substrate from the backing since they shrink at different rates.
Traces of acid produced by air pollution accelerate hydrolysis. Sulphur dioxide, according to NIST, forms strong acids in humid air. Other common gases are nitrogen dioxide, ozone, acetic acid, and formaldehyde. Videotape restorers see the worst damage stemming from hostile storage environments.
Why a professional should copy my film or tapes?
A professionals help minimizes the imperfections while transferring the tape to a new copy or digital format. They will take obsolete formats and re-format them by converting the original to an updated format. From 1956 to the present more than 100 fundamentally incompatible video formats have been introduced into the market place. It is important to distinguish between copying, transferring and restoration. Copying is the straightforward dubbing or duplication of a tape, as in making a reference copy for routine use or to service another format. Transferring, remastering, or re-formatting involves converting the original to an updated format. This might involve some restoration because of either physical or chemical damages and this implies a deliberate effort to make a complete and error-free copy from the original.
The goal is to reduce any imperfections and handle the fragile videotapes with special care while transferring to a new copy. Cleaning the tape properly beforehand is part of restoration and it is recommended to use a professional to help you update your video format. This will decrease your chance accidentally damaging your videotapes and losing your memories.
A physical inspection includes a more or less automated or manual evaluation of the tape, examining for imperfections visible to the laboratory technician such as exudations of white crystal powder, shedding, stiction, scratches, or fungus and deformities in the tape pack such as creases, cracking, stretching, uneven wind, or edge damage. Some of the physical defects such as edge damage, wrinkles, and creases can be identified with electronic cleaning/inspection machines. Before transferring, the cleaning of the tape’s loose oxide and other debris is necessary. Most of this is accomplished with cleaning blades or polish points or dry paper wipes or even washing with water.
The machines that professionals use will also measure dropout according to preset standards. In reality these machines are both inspectors and cleaners, designed for use with pre-recorded tape. They are designed to remove dirt, dust and loose particles that cause dropouts.
Hovering over the obsolescence as a preservation issue it is the more straightforward need of large recordings to be able to copy tens or even thousands of hours of videotape before the supporting technology disappears from the market place.
Other VHS Playback Issues
There are other problems the videotape encounters which interferes with the ability to playback and result in the tape’s utter destruction.
1). Edge damage– One of the most common problems is tape edge damage typically caused by misaligned transports. Physical damage (stretching, nicks, and dents, etc.) cause the track to skip as the tape moves through the guide paths.
2). Shedding– In addition to the shedding that results from chemical breakdown, shedding is caused by poorly maintained equipment. Many tapes manufactured up to the early 1970’s are notorious for their shedding due to difficulties inherent in the relatively weak bond between the binder and the substrate. By 1970 3M, Ampex, and Memorex had developed more reliable techniques for binding the magnetic layer to the polyester base. The shedding seen in later tapes is the result of binder breakdown or poor operating conditions. Nonetheless, the older tapes are larger and they shed more. A one-hour 2 inch Quad tape has 108,000 square inches; a one hour 1/2 inch VHS at standard speed has only 2,360 square inches. The design of older tapes are more tape-to-head contact and thus produced more friction.
3). Fungus– Contamination of videotape by fungus or mildew is fairly common. Warm and humid conditions encourage fungus, which attacks the organic materials in the binder. Tapes or cassettes exposed to water or moisture from floods or sprinklers are prone to fungus, especially if moisture becomes trapped inside the cassette.
4). Dirt– Dirt and other debris can destroy a tape or impede its ability to properly follow the track evenly. Dirt from any source can become embedded in the binder emulsion. Static electricity will attract dirt.
5). Containers– Little research was conductedon containers or cassettes for videotape, but they are also a reason in longevity. Open-reel recordings are far more vulnerable to damage than those protected by cassettes. Some cassette housings are not dust proof in the locked position. Interior components can degrade, such as springs and rubber materials from the moisture trapped inside. Hinges can wear out. Standard VHS cassettes contain more than 30 parts in assembly. In a pilot study, NIST observed that many cassettes showed mechanical problems after accelerated aging or after five years of natural aging. A damaged cassette, if not detected, can result in irreparable tape damage.
6). Storage– For long-term storage of videotapes, we recommend cooler and drier conditions but this doesn’t dispute the likelihood that videotape will outlast the equipment intended for playback.
7). Shelving– Metal shelving, widely used for storing videotape, does not seem to be a problem provided the shelves are properly grounded. Certain paints and finishes may be a problem if they continue to give off gas after tapes are placed on metal shelves. Wood is not acceptable for archival storage of videotape because of acid vapors emitted from wood or wood finishes. In addition, wood shelves are a factor in spreading flames in a fire emergency.
8). Security and Fire Protection– videotapes are susceptible to theft and water damage from fire emergencies and sprinkler accidents.
9). Copying, Transferring and Restoration– It bears repeating that imperfections develop in magnetic tape primarily from inherent deficiencies such as poor layer adhesion in the early formulations, from the ravages of poor storage conditions, and from physical problems such as creases, edge damage, poor winds, and embedded dirt. Dirt is all-pervasive, observed one video restorer. It is important to distinguish between copying, transferring and restoration. Copying is the straightforward dubbing or duplication of a tape, as in making a reference copy for routine use or to service another format. Transferring, remastering, or re-formatting involves converting the original to an updated format. Restoration implies a deliberate effort to make a complete and error-free copy from the best available original, minimizing all imperfections, while transferring the tape to a new copy. Cleaning the tape beforehand is part of restoration.
Analog Videotape Formats
|2-inch||Iron Oxide||2 – inch||Broadcasters/Studios|
|½-inch open reel||Iron Oxide||½ – inch||Independent Production|
|1-inch Type A||Iron Oxide||1 – inch||Government/Studios|
|¾-inch U-matic||Cobalt-Modified Iron Oxide||¾ – inch||ENG/Independent Production|
|¾-inch Umatic SP||Cobalt-Modified Iron Oxide||¾ – inch||ENG/Independent Production|
|Beta||½ – inch||Consumer|
|Betacam||Cobalt-Modified Iron Oxide, Chromium Dioxide||½ – inch||ENG/Independent Production/Government|
|Betacam SP||Metal Particle||½ – inch||ENG/Independent Production|
|M-II||Metal Particle||½ – inch||ENG/Broadcasting|
|1 – inch TYpe C||Cobalt-Modified Oxide||1 – inch||Broadcasting/Studios|
|8mm, HI 8||Metal Particle, Evaporated Metal||8mm||Consumers/ENG/Government/ Independent Production|
|VHS||Cobalt-Modified Oxide, Chromium Dioxide||½ – inch||Consumers/Government|
|S-VHS||Cobalt-Modified Oxide||½ – inch||Independent Production/ENG|
Source: Anon Loc.gov. (2016). [online] Available at: http://www.loc.gov/programs/static/national-film-preservation-board/documents/tvstudy.pdf [Accessed 4 Nov. 2016].