There are basic technical reasons why an archive does not last, namely the quality of the material on which the record is kept. The ink used today, which is based on aniline, becomes virtually unreadable after about thirty years - and the ink from a typical ballpoint pen becomes unreadable after a few hours in the sun! Today, the original documents produced in the Nuremberg trials of 1945 are almost undecipherable. The quality of the paper used has as great an effect on the durability of documents. Paper manufactured before about 1840, being made of textiles ("rag") and of glues derived from the bones of animals, was long-lasting. Most of the paper made during the next century was not, for the pine resin used as glue destroys its cellulose fibers (the paper being a wood product). While deacidification processes have since been developed and are being gradually applied to the most precious surviving records, and while much of the paper produced since 1945 is not similarly vulnerable, a huge proportion of the documents stored in libraries and archives today is threatened with extinction simply because the paper is rotting.
Research and Testing Series
"This series of reports is the result of research carried out for the Preservation Research & Testing Division, either by its own staff or under contract with other institutions or private vendors..."
Digitizing Visual Materials
"The following publications were created for the Preservation Directorate of the Library of Congress. They provide technical guidelines and requirements for achieving digital image capture for preservation purposes."
Care and Handling of CDs and DVDs - A Guide for Librarians and Archivists
by Fred R. Byers, October 2003
Council on Library and Information Resources
National Institute of Standards and Technology
[This] document provides guidance on how to maximize the lifetime and usefulness of optical discs, specifically CD and DVD media, by minimizing chances of information loss caused by environmental influences or physical handling... This document is intended neither to represent nor imply a standard. It is merely a consensus of several reliable sources on the prudent care of CDs and DVDs...
With CDs and DVDs, the user does not notice early degradation because the error detection and correction capability built into the system corrects a certain number of errors. The user notices a problem only when the error correction coding is unable to fully correct the errors... life of a disc is considered at its end when the error rate exceeds a predermined limit, as measured before the error correction process, even if the disc is still playable and the errors are not noticeable to the user.
Manufacturers claim that CD-R and DVD-R discs have a shelf life of 5 to 10 years before recording, but no expiration dates are indicated on CD-R, DVD-R, or DVD+R packaging, nor are there published reports of tests to verify these claims...
In theory, R discs should have a limited number of read times (several thousand) because of the cumulative effect on the data layer from the laser light... CD-RW and DVD-RW discs should last for about 1,000 rewrites, and DVD-RAM discs, 100,000 times, before the rewriting capability is lost. The reading functionality of the disc should continue for a limited number of read times after each writing. While the maximum number of read times possible after writing is unknown, it may become fewer after each successive writing...
Among the manufacturers that have done testing, there is consensus that, under recommended storage conditions, CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more; CD-RW, DVD-RW, DVD+RW, and DVD-RAM discs should have a life expectancy of 25 years or more. Little information is available for CD-ROM and DVD-ROM discs (including audio and video), resulting in an increased level of uncertainty for their life expectancy. Expectations vary from 20 to 100 years for these discs.
Few, if any, life expectancy reports for these discs have been published by independent laboratories. An accelerated aging study at NIST estimated the life expectancy of one type of DVD-R for authoring disc to be 30 years if stored at 25°C (77°F) and 50% relative humidity. This testing for R discs is in the preliminary stages, and much more needs to be done.
Table 3: Recommended storage parameters from different sources
Pressed discs (the kind that movies come on) should last longer than you will, anywhere from 50 to 300 years.
Expected longevity of dye-based DVD-R and DVD+R discs is anywhere from 20 to 250 years, about as long as CD-R discs. Some dye formulations (such as phthalocyanine and azo) are more stable and last longer, 100 years or more compared to 20 or 30 years for less stable dyes.
The phase-change erasable formats (DVD-RAM, DVD-RW, and DVD+RW) have an expected lifetime of 25 to 100 years.
In all cases, longevity can be reduced by poor quality. Poor quality pressed DVDs may deteriorate within a few years, and cheap recordable DVDs may cause errors when recording or may become unreadable after a while. (See 1.24.)
There's a good discussion of CD-R longevity and test info at Kodak. Also see <www.ee.washington.edu/conselec/CE/kuhn/otherformats/95x9.htm> and <www.cd-info.com/CDIC/Technology/CD-R/Media/Kodak.html> for more info.
For comparison, magnetic media (tapes and disks) last 10 to 30 years; high-quality, acid-neutral paper can last 100 years or longer; and archival-quality microfilm is projected to last 300 years or more. Note that computer storage media often becomes technically obsolete within 20 to 30 years, long before it physically deteriorates. In other words, before the media becomes unviable it may become difficult or impossible to find equipment that can read it...
Videotape, laserdisc, and CD-ROM can't be compared to DVD in a straightforward manner. There are basically three stages of costs: production, pre-mastering (authoring, encoding, and formatting), and mastering/replication.
DVD video production costs are not much higher than for VHS and similar video formats unless extra features of DVD such as multiple sound tracks, camera angles, seamless branching, etc. are employed.
Authoring and pre-mastering costs are proportionately the most expensive part of DVD. Video and audio must be encoded, menus and control information have to be authored and encoded, it all has to be multiplexed into a single data stream, and finally encoded in low level format. Typical charges for compression are $50/min for video, $20/min for audio, $6/min for subtitles, plus formatting and testing at about $30/min. A ballpark cost for producing a Hollywood-quality two-hour DVD movie with motion menus, multiple audio tracks, subtitles, trailers, and a few info screens is about $20,000. Alternatively, many facilities charge for time, at rates of around $300/hour. A simple two-hour DVD-Video title with menus and various video clips can cost as low as $2,000. If you want to do it yourself, authoring and encoding systems can be purchased at prices from $50 to over $2 million...
Videotapes don't really have a mastering cost, and they run about $2.40 for replication. CDs cost about $1,000 to master and $0.50 to replicate. Laserdiscs cost about $3,000 to master and about $8 to replicate. As of 2003, DVDs cost about $1000 to master and about $0.70 to replicate. Double-sided or dual-layer discs cost about $0.30 more to replicate, since all that's required is stamping data on the second substrate (and using transparent glue for dual layers). Double-sided, dual-layer discs (DVD-18s) are more difficult and more expensive...
How long will my CD-R last?
That depends on what CD-R you use and how you take care of it. Mitsui CD-Rs use their own phythalocyanine dye, which they developed. Because of their dye material's strengths, Mitsui gold CD-Rs feature a shelf life of 250 years, a fact that makes them archival standard. Mitsui silver CD-Rs have a shelf life of 100 years, still pretty nice. Cyanine dye CD-Rs have a shelf life of 30 to 100 years, but the bigger issue with Cyanine CD-Rs is the way they are impacted by light. Leave a Cyanine CD-R on the seat of your car, and you'll lose the content quickly. Leave a Phthalocyanine dye Mitsui CD-R in the same place and you'll find it much less susceptible to the light. Any CD-R you use should be kept away from direct sunlight just to be safe.
A real understanding of how long a given CD-ROM is going to be effectively... In 1992 the National Institute of Standards and Technology (NIST) published Development of a Testing Methodology to Predict Optical Disk Life Expectancy Values. The study methodology used "accelerated aging," which assumes that temperature and relative humidity (RH) are the crucial variables that, over time, affect optical media longevity:
'...with storage at nominal room temperature and 90 percent humidity [results indicate that] the most conservative estimate is 57 years, while a more liberal estimate is 121 years. In either case, a relative humidity between 40 and 50 percent should lead to an even longer life expectancy.' (NIST, 1992)
The life of a videotape is difficult to predict. Some tapes
deteriorate after three or four years (under extreme humidity
deterioration can occur in even shorter periods). Conversely
ScreenSound Australia holds tapes which are over 30 years old and
still replay well.
Preservation & Technical Services Branch
ScreenSound Australia, the National Screen and Sound Archive
Title: OSHA Compliance Records.
Information Date: 08/03/1998
Purpose: This directive provides instructions and procedures for the maintenance and disposition of OSHA compliance case files and related files, including mixed-media files, that are concerned with federal inspection of work sites including those in Federal agencies...
Videotape Lifetime. The expected lifetime for videotape is approximately 10+ years in an environment that is not climate controlled. This means the quality of the image cannot be guaranteed more than 10 years. The environment in most FRC's is not climate controlled.
The National Media Laboratory, a research organization in St. Paul, Minn., estimates that data stored on a CD-ROM will be safe for only 10 years on average, 50 years under ideal conditions. Material on magnetic tape lasts an average of five years, 10 years at best, unless it is recopied.
If stored properly, conventional color photographs printed from negatives can last as long as 75 years without fading...
Peter Hite, president of Media Management Services in Houston, a consulting firm that helps companies manage their digital and historical archives... said the life span of a CD recorded with a CD burner could be as short as five years because of exposure to humidity and extreme temperatures. And magnetic storage media, like floppy disks, can begin to deteriorate after as little as 18 months because of abrasion and demagnetization...
Epson and other printer manufacturers have started selling printers that use longer-lasting ink and paper. Depending on the paper you use and how well you protect your prints, photos printed on Epson's 2000P desktop printer, which costs $899, can last as long as 200 years, the company says. The printer uses inks with special pigments, which cost more than dye-based ink, and long-lasting paper.
Sat Jan 24 2004 [00:21] Interviewer: I wanna archive some original videotapes to DVD [00:21] Interviewer: Have you looked into who claims longest DVD media life... [00:22] Interviewer: Originally people kept saying 100 years, but you hear 5-year horror stories about CD-R [00:23] Expert: I've had some CD-R's go unreadable in as little as two years... [00:23] Interviewer: yikes! [00:23] Expert: it depends on the dye used. [00:23] Interviewer: Did you have second copies to regenerate? [00:23] Expert: Yeah, I did... [00:24] Expert: this was all stuff that was mastered onto a production CD... [00:24] Expert: The TOC was wiped. [00:25] Expert: I had duplicates on a longer lasting CD. [00:25] Expert: But for CD-R, you have to pay attention to the dyes used. [00:25] Interviewer: How much does a 1000-unit pressed run cost these days? [00:25] Interviewer: Long before there were CD-Rs price went under $1/disk at that qty [00:25] Expert: About .20 per. [00:26] Expert: it's priced similar to semiconductors - discrete steppings. [00:27] Expert: Most of the price isn't in the media.. [00:27] Expert: it's in handling. [00:27] Interviewer: Do people press runs under 1000? Or too expensive? [00:27] Expert: Sure - 500 minimum... [00:28] Expert: at which point you're paying right around .30 per. [00:28] Expert: Plus whatever the setup fees are... [00:28] Expert: plus cover publishing. [00:29] Interviewer: How much may they be? [00:29] Expert: That varies so wildly I hesitate to give a figure. [00:29] Interviewer: Where do you look for the best deals? Mags? Web sites? Price engines online? [00:29] Expert: Publishing trade rags, usually. [00:30] Expert: Or music trade rags. [00:30] Interviewer: like? "Plasticpress"?
[00:30] Expert: Not quite. Musicmaker, for example. ;) [00:31] Expert: But if you're looking for a low-volume run... [00:33] Expert: If you're talking just a couple of hundred... [00:33] Expert: look into a duplicator. [00:39] Expert: [$]165 for 500 pcs of archival silver dye. [00:39] Interviewer: silver dye is best quality? [00:39] Expert: Yep. [00:39] Interviewer: Are "all silvers" created equal? [00:40] Interviewer: Brand differences? [00:40] Expert: Pretty much, since there are only three manufacturers... [00:40] Expert: even though there are about 400 brand names. ;) [00:40] Expert: Ritec is pretty decent.
These standards reflect SIA requirements for digitization of images. These standards reflect available best practices applied in the context of SI Archives resource constraints at a specific point in time.
...Images are stored redundantly on DVD-R/DVD+R format optical media with a minimum of 2 offline copies: a preservation ‘master’ and a preservation ‘backup’...
An additional set may be created for reference/public access which may exist online, if permissions/rights issues and internal policies allow. The preservation master DVD disk is to be stored in appropriate offsite archival storage. Technical information regarding creation date of the disks and software used for disk creation is to accompany the disks...
No labels are to be affixed directly to the DVD disk. No markers are to be used to label the DVD disk. Both of these activities have been proven in national studies to degrade the archival life of the DVD.