Media preservation

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Preservation of documents, pictures, recordings, digital content, etc., is a major aspect of archival science. It is also an important consideration for people who are creating time capsules, family history, historical documents, scrapbooks and family trees. Common storage media are not permanent, and there are few reliable methods of preserving documents and pictures for the future.

Contents

Paper/prints (photos)

Color negatives and ordinary color prints may fade away to nothing in a relatively short period if not stored and handled properly. This happens even if the negatives and prints are kept in the dark, because ambient light is not the determining factor, but heat and humidity are. The color degradation is the result of the dyes used in the color processes. Because color processing results in a less stable image than traditional black-and-white processing, black-and-white pictures from the 1920s are more likely to survive long-term than color films and photographs from after the middle 20th century.

Black-and-white photographic films using silver halide emulsions are the only film types that have proven to last for archival storage. The determining factors for longevity include the film base type, proper processing (develop, stop, fix and wash) and proper storage. Early films used a Cellulose nitrate base which was prone to decomposition and highly flammable. Nitrate film was replaced with acetate-base films. These Cellulose acetate films were later discovered to outgass acids (also referred to as vinegar syndrome). Acetate films were replaced in the early 1980s by polyester film base materials which have been determined to be more stable than film stocks with a nitrate or acetate base.

Color prints made on most inkjet printers look very good at first but they have a very short lifespan, measured in months rather than in years. Even prints from commercial photo labs will start to fade in a matter of years if not processed properly and stored in cool, dry environments.

Documents/books

With documents for which the media are not so critical as what the documents contain, the information in documents can be copied by using photocopiers and image scanners. Books and manuscripts can also have their information saved without destruction by using a book scanner.

Where the medium itself needs to be preserved, for example if a document is a crayon sketch by a famous artist on paper, a complex process of preservation may be used. Depending on the condition and importance of the item this can include gluing the media onto more stable media, or protective enclosing of the media. Polyester sleeves, acid-free folders, and pH buffered document boxes are common supportive protective enclosures whose selection must match the media's chemical and physical properties. [1] Other considerations in preserving paper/books are:

Online photo albums

Although there are many websites that allow the upload of photographs and videos, digital preservation for the long-term is still considered an issue. There is a lack of confidence that such websites are capable of storing data for long periods of time (ex. 50 years) without data degradation or loss. [2]

Optical media - CD, DVD, Blu-ray, M-Disc

Write-once optical media, such as CD-Rs and DVD-Rs, typically contain an organic dye that distinguishes data reading from data writing based on the dye's transparency along the disc. [3] Conventional CDs and DVDs have finite shelf-life due to natural degradation of the dye; the newer M-DISC uses inorganic material technology to produce molded DVDs and Blu-Rays (up to 3-layer 100GB BDXL) with a claimed lifespan of 100-1000 years if stored correctly with most BD & BDXL rated read/writers enabling the higher power mode for the M-Disc format after 2011. The National Archives and Records Administration lists published life expectancies to be 10 or 25 years or more for normal CDs and DVDs and conservative life expectancies to be between 2 and 5 years. [4] Storage environments, such as temperature and humidity, as well as handling conditions such as frequency of media use and compatibility between the recorder and media, affect media shelf-life. [5] Improvements in media storage and migrations to new recording technologies can make certain formats obsolete within their respective lifespan. Technologists have pointed to internet streaming services, where services such as video-on-demand have contributed to the 33 percent decline in DVD sales the past 5 years, as a challenge for digital preservation. [6]

Magnetic media - video cassettes, tapes, hard drives

Magnetic media such as audio and video tape and floppy disks also have limited life spans.

Audio and video tapes require specific care and handling to ensure that the recorded information will be preserved. For information that must be preserved indefinitely, periodic transcription from old media to new ones is necessary, not only because the media are unstable but also because the recording technology may become obsolete.

A badly molded VHS tape. Mold can grow due to humidity on the storage space, and then prevent modern usage. Molded VHS tape.jpg
A badly molded VHS tape. Mold can grow due to humidity on the storage space, and then prevent modern usage.

Magnetic media also deteriorates naturally with typical shelf lives between 10 and 20 years. [7] Magnetic tape can degrade from binder hydrolysis or magnetic remanence decay. Binder hydrolysis, also known as sticky-shed syndrome, refers to the breakdown of binder, or glue, that holds the magnetic particles to the polyester base of the tape. Tapes which have been stored in hot, humid conditions are particularly vulnerable to this phenomenon and may suffer from accelerated degradation. Severe binder can cause the magnetic material to fall off or sheds from the base, leaving a pile of dust and clear backing. Archivists can bake the tape, which evaporates water molecules on the tape, to temporarily restore the binder before making a copy.

Magnetic tape can also be destabilized by magnetic remanence decay, which refers to the weakening of the tape's magnetization over time. This weakens the affected tape's readability, leading to reduced sound clarity and volume or picture hue and contrast. Baking the tape will not restore magnetization.

Media at risk include recorded media such as master audio recordings of symphonies and videotape recordings of the news gathered over the last 40 years. Threats to media that must be considered when archiving important record media include accidental erasure, physical loss due to disasters such as fires and floods, and media degradation.

Along with the actual media being degraded over the years, the machines that are available to play back or reproduce the audio sources are becoming archaic themselves. Manufacturers and their support (parts, technical updates) for their machines have disappeared throughout the years. Even if the medium is vaulted and archived correctly, the mechanical properties of the machines have deteriorated to the point that they could do more harm than good to the tape being played.

Many major film studios are now backing up their libraries by converting them to electronic media files, such as .AIFF or .WAV-based files via digital audio workstations. That way, even if the digital platform manufacturer goes out of business or no longer supports their product, the files can still be played on any common computer.

There is a detailed process that must take place previous to the final archival product now that a digital solution is in place. Sample rates and their conversion and reference speed are both critical in this process.

In floppy disks, the lubricants inside the plastic jackets of many older floppies promote the decay of the magnetic medium. Also, the alignment of the magnetic particles of the disk substrate may gradually degrade, leading to a loss of formatting and data. Early laser disk media were prone to degradation as the layers of the disk substrate were bonded with an adhesive that was vulnerable to decay and would crumble over time. This would lead the different layers of the disk to peel apart, damaging the pitted data surface and rendering the disk unreadable.

See also

Related Research Articles

<span class="mw-page-title-main">Computer data storage</span> Storage of digital data readable by computers

Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.

<span class="mw-page-title-main">Disk storage</span> General category of storage mechanisms

Disk storage is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism. Notable types are today's hard disk drives (HDD) containing one or more non-removable rigid platters, the floppy disk drive (FDD) and its removable floppy disk, and various optical disc drives (ODD) and associated optical disc media.

<span class="mw-page-title-main">Magnetic tape</span> Medium used to store data in the form of magnetic fields

Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic tape could with relative ease record and playback audio, visual, and binary computer data.

<span class="mw-page-title-main">Data storage</span> Recording of information in a storage medium

Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are considered by some as data storage. Recording may be accomplished with virtually any form of energy. Electronic data storage requires electrical power to store and retrieve data.

<span class="mw-page-title-main">Optical disc</span> Flat, usually circular disc that encodes binary data

An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side.

A hard disk recorder (HDR) is a system that uses a high-capacity hard disk to record digital audio or digital video. Hard disk recording systems represent an alternative to reel-to-reel audio tape recording and video tape recorders, and provide non-linear editing capabilities unavailable using tape recorders. Audio HDR systems, which can be standalone or computer-based, are typically combined with provisions for digital mixing and processing of the audio signal to produce a digital audio workstation (DAW).

<span class="mw-page-title-main">Film preservation</span> Historic preservation of motion pictures

Film preservation, or film restoration, describes a series of ongoing efforts among film historians, archivists, museums, cinematheques, and non-profit organizations to rescue decaying film stock and preserve the images they contain. In the widest sense, preservation assures that a movie will continue to exist in as close to its original form as possible.

Data degradation is the gradual corruption of computer data due to an accumulation of non-critical failures in a data storage device. The phenomenon is also known as data decay, data rot or bit rot. This process leads to the slow deterioration of data quality over time, even if the data is not actively being used or accessed.

In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", whereas the noun and adjective form is "backup". Backups can be used to recover data after its loss from data deletion or corruption, or to recover data from an earlier time. Backups provide a simple form of disaster recovery; however not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server.

<span class="mw-page-title-main">Magnetic storage</span> Recording of data on a magnetizable medium

Magnetic storage or magnetic recording is the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetisation in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using one or more read/write heads.

<span class="mw-page-title-main">Digital obsolescence</span> Data loss as the format goes into disuse

Digital obsolescence is the risk of data loss because of inabilities to access digital assets, due to the hardware or software required for information retrieval being repeatedly replaced by newer devices and systems, resulting in increasingly incompatible formats. While the threat of an eventual "digital dark age" was initially met with little concern until the 1990s, modern digital preservation efforts in the information and archival fields have implemented protocols and strategies such as data migration and technical audits, while the salvage and emulation of antiquated hardware and software address digital obsolescence to limit the potential damage to long-term information access.

Digital permanence addresses the history and development of digital storage techniques, specifically quantifying the expected lifetime of data stored on various digital media and the factors which influence the permanence of digital data. It is often a mix of ensuring the data itself can be retained on a particular form of media and that the technology remains viable. Where possible, as well as describing expected lifetimes, factors affecting data retention will be detailed, including potential technology issues.

<span class="mw-page-title-main">Optical storage</span> Method to store and retrieve computer data using optics

Optical storage refers to a class of data storage systems that use light to read or write data to an underlying optical media. Although a number of optical formats have been used over time, the most common examples are optical disks like the compact disc (CD) and DVD. Reading and writing methods have also varied over time, but most modern systems as of 2023 use lasers as the light source and use it both for reading and writing to the discs. Britannica notes that it "uses low-power laser beams to record and retrieve digital (binary) data."

etree

etree, or electronic tree, is a music community created in the summer of 1998 for the online trading of live concert recordings. etree pioneered the standards for distributing lossless audio on the net and only permits its users to distribute the music of artists that allow the free taping and trading of their music.

<span class="mw-page-title-main">Preservation of magnetic audiotape</span>

Preservation of magnetic audiotape comprises techniques for handling, cleaning and storage of magnetic audiotapes in an archival repository. Multiple types of magnetic media exist but are mainly in the form of open reels or enclosed cassettes. Although digitization of materials on fragile magnetic media in library and information science is a common practice, there remains a need for conserving the actual physical magnetic tape and playback equipment as artifacts.

Oral history preservation is the field that deals with the care and upkeep of oral history materials, whatever format they may be in. Oral history is a method of historical documentation, using interviews with living survivors of the time being investigated. Oral history often touches on topics scarcely touched on by written documents, and by doing so, fills in the gaps of records that make up early historical documents.

The preservation of optical media is essential because it is a resource in libraries, and stores audio, video, and computer data to be accessed by patrons. While optical discs are generally more reliable and durable than older media types, environmental conditions and/or poor handling can result in lost information.

<span class="mw-page-title-main">Cellulose acetate film</span> Base material for photographic emulsions

Cellulose acetate film, or safety film, is used in photography as a base material for photographic emulsions. It was introduced in the early 20th century by film manufacturers and intended as a safe film base replacement for unstable and highly flammable nitrate film.

The conservation and restoration of time-based media art is the practice of preserving time-based works of art. Preserving time-based media is a complex undertaking within the field of conservation that requires an understanding of both physical and digital conservation methods. It is the job of the conservator to evaluate possible changes made to the artwork over time. These changes could include short, medium, and long-term effects caused by the environment, exhibition-design, technicians, preferences, or technological development. The approach to each work is determined through various conservation and preservation strategies, continuous education and training, and resources available from institutions and organization across the globe.

The conservation and restoration of film is the physical care and treatment of film-based materials. These include photographic film and motion picture film stock.

References

  1. "Care, Handling, and Storage of Works on Paper". Library of Congress.
  2. Webster, John (2009-08-13). "How long is long-term storage? | Data-driven - CNET News". News.cnet.com. Retrieved 2012-03-05.
  3. Library of Congress, "NIST/LC: Optical Disc Longevity Study," https://www.loc.gov/preservation/resources/rt/NIST_LC_OpticalDiscLongevity.pdf
  4. National Archives and Records Administration, "Frequently Asked Questions (FAQs) about Optical Storage Media: Storing Temporary Records on CDs and DVDs, National Archives," https://www.archives.gov/records-mgmt/initiatives/temp-opmedia-faq.html
  5. UKOLN, "Digital Archaeology: Rescuing Neglected and Damaged Data Resources," http://www.ukoln.ac.uk/services/elib/papers/supporting/pdf/old-p2.pdf
  6. Saylor, Michael (2012). The Mobile Wave: How Mobile Intelligence Will Change Everything. Perseus Books/Vanguard Press. p. 86.
  7. Broadway Video Digital Media, "Causes and Measurement of Videotape Decay," http://sportsvideo.org/main/files/2010/08/video-tape-white-paper.pdf