CD-rom longevity

The following originally appeared on "Publishing E-Journals :
Publishing, Archiving, and Access" <VPIEJ-L [at] VTVM1__BITNET> and was
reposted in GOVDOC-L and is reposted here without the knowledge or
consent of the author

  Someone passed the following to me regarding CD-ROM life which was
  published in the newsletter of OCLC Pacific Network (PACNET):

    "A number of libraries have taken to heart various manufacturers'
    claims that CD-ROM discs will last twenty years.  However, recent
    statements by the National Archives and Records Administration
    (NARA) have placed a damper on these extravagant estimates.  NARA
    states that the expected lifespan of CD-ROMs is three to five years.
    A later report will provide more detailed information, but the main
    problem, according to Ken Thibodeau of NARA, is that the aluminum
    substrate on which the data is recorded is vulnerable to oxidation
    (breakdown in the presence of oxygen).  This was confirmed in
    statements to NARA by representatives of 3M Corporation, the largest
    CD-ROM fabricator.

    The plastic that protects the substrate is oxygen permeable, so it
    provides no protections against the oxidation process.  In fact,
    oxidation begins during the manufacturing process itself because
    there is no attempt to evacuate the air between the substrate and
    the plastic coating.  It is claimed that preventing air from being
    introduced during manufacturing is cost prohibitive.

    The only coating presently available that could possibly protect
    against the oxidation process is glass.  However, glass has other
    problems associated with it, including breakage.  Additionally, the
    problem of evacuating air during manufacturing would probably remain
    a factor in the construction of glass-coated discs.

    Libraries that have considered eliminating paper subscriptions and
    substituting CD-ROM storage clearly need to re-evaluate their
    policies in the light of this information."

    Cynthia A. Hodgson
    Aluminum Company of America
    hodgson [at] alcoa__com
    (412) 337-2434

  -----
  Jan I. Wolitzky
  AT&T Bell Laboratories
  600 Mountain Avenue, Room 3D-590
  Murray Hill, NJ 07974-2070 USA
  1 908 582-2998
  Fax: 1 908 582-5417
  wolit [at] mhuxd__att__com

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                  Conservation DistList Instance 5:47
                  Distributed: Thursday, April 2, 1992
                        Message Id: cdl-5-47-002
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