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Preservation of document, 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 It is also an important consideration for people who are creating time capsules, family history, historical documents, scrapbooks and family trees.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.
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Paper/prints
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 the ambient light is not the determining factor, but heat and humidity are. 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 into the long term future than those color films and photographs from the last 20 or 30 years. The cause of the color degradation is the result of the dyes used in the color processes.
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.
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 were coated onto a nitrate base material which was prone to combustion if stored in uncontrolled temperatures, Nitrate was replaced with acetate-base films. The acetate films have now been 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 that nitrate and acetate base films.
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Digital images
According to digital storage experts, media such as zip disks, CDs, or DVDs last only a definite period before the medium begins to degrade although the fact that these media formats are recent inventions combined with a high rate of change and improvements in these technologies makes it difficult to determine how long digital media will last. Manufacturers claim minimum lifetimes of 50 years for CD-Rs and 25 years for CD-RWs.[ These experts suggest that digital images be transferred as new media are developed to ensure that they are preserved.]
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Magnetic media, videocassettes, tapes, hard drives
As with CDs and computer hard drives, Magnetic media such as audio and videotapes have a very limited life span.
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 is necessary, not only because the media are unstable, but also because the recording technology may become obsolete.
The magnitude of the problem of magnetic tape deterioration is just starting to be realized. according to some research, there is a good chance that magnetic tape older than 10 years will deteriorate. The threat comes from several sources, but the largest threat is chemical in nature, coming from the breakdown of the binder, or glue, that holds the magnetic particles to the polyester base of tape. As this occurs, the tape often gets coated with a tenacious adhesive that makes it extremely difficult to play. In some cases the problem can be so severe that the magnetic material literally falls off or sheds from the base leaving a pile of dust and clear backing.
This problem has been known for some time, but the extent of both the problem and catastrophic effect it has on magnetic media is just now gaining visibility. It is also common for computer floppy disks to degrade over time, as the lubricants inside of 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 degrade over time, leading to a loss of formatting and data. Early laserdisk media was 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.
Media at risk includes 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 fire and flood, and media degradation.
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