To Larry's posting, I'll add ISO 18925: 2013 Imaging materials - Optical disc media - Storage practices and
ISO 18938:2008 Imaging materials - Optical discs - Care and handling for extended storage

Come to think of it, ISO standards are supposed to be on a five year cycle so every five years we were supposed to either revise/update, reaffirm, or withdraw standards, although I remember a lot of standards that went longer than five years without action. However, it does technically mean that the latter standard for care and handling should be up for review, if not now, then soon.

By the way, waaay back in the 1970s, the corresponding ANSI standard sub-committee to ISO TC 42/working group (WG) 5, ANSI PH1-3, tried to define "archival". By 1990 we realized that there was no standard definition for "archival." Photographic people said at least 100 years, magnetic tape people said 15 years and the fledgling optical group industry said 2 years. So we did away with the term "archival" as a reference to some minimum given life expectancy and created the term "extended term." Defining it was still difficult, but at least we didn't have the range of 2 years to centuries.

In this age of digital storage, the words of Dr. James B. Rhoads, then Archivist of the United States, are rather significant. If I may be allowed to transcribe the letter from Dr. Peter Adelstein, then Chair of ANSI PH1-3 and Dr. Rhoads' reply.

"
				December 10, 1975


Dr. James B. Rhoads
Archivist of the United States
Washington, D.C.

Dear Dr. Rhoads:
 
In 1971, a special Task Group was organized within Subcommittee PH1-3 of the American National Standards Institute with the assignment of preparing specifications for diazo and vesicular films intended for storage purposes. It was recognized early in the Task Group deliberations that there are different criteria of film storage, depending upon the requirements of the user. Currently, three film classifications are being considered, medium term film, long term film, and archival film. Medium and long term films represent new classifications and they are being defined as films capable of a useful life of either 10 or 100 years respectively. However, the term 'archival' film has been in use for many years and any new 'archival film' specification must be consistent with the existing meaning of this phrase. There is some confusion within the Task Group as to the minimum life of archival materials and the density changes that are tolerable.

We recognize that the National Archives are the ultimate authority on this subject in the United States. Accordingly we would appreciate some clarification and guidance as to the exact meaning of 'archival' so that any new sepficiations would conform to current practice in this country. 

P. Z. Adelstein
Chairman, ANSI PH1-3 Task Group on Vesicular and Diazo Film"

"
				December 15, 1975

Dr. Peter Z. Adelstein
Chariman, ANSI PH1-3 Taks Group on
Vesicular and Diazo Film
Eastman Kodak Company
Rochester, New York 14650

Dear Dr. Adelstein:

This is in reply to your letter of December 10 in which you requested clarification on the meaning of the word 'archival'. I am aware that there has been confusion and frustration among your group in dealing with this term. It is my hope that I can clarify its meaning as it applies to media used for the filming of records for permanent retention.

Essentially the term 'archival' is synonomous [sic] with 'permanent' and the two are frequently used interchangably. [sic] To us they have the same meaning: that is, forever. To say that we are going to keep forever everything that is now classified as archival or permanent is a rather positive statement and one which none of us can guarantee. Yet it does express our intention in relation to records which have been appraised as being of permanent value, or archival.

This clarification is important because it is necessary that whatever material is approved for permanent record filming must be equal to or better than the present materials that have been certified for permanent record use. For this reason the standards that this or similar groups develop must be stringent so that only those of the highest quality will ultimately be approved.

Permanent or archival record film can be defined as any film that is equal to or better than silver film, as specified in ANSI specifications PH1.28 and PH1.41. [These two standards were combined and now exist as ISO 18901:2010 - Doug] We realize that equating other film types to silver may not be the best criteria, but at this time it is the only standard that we have. Silver has been around long enough to lend some credence to its stability as an archival materials, yet if newer materials can be qualified they too should be considered for certification.

Sincerely,

James B. Rhoads
Archivist of the United States.

The letters from Drs. Adelstein and Rhoads were published in the Journal of Micrographics, Volume 9, No. 4 March 1976 pages 193 - 194. 

As we turn away from microfilm for information storage, it's interesting that the digital replacement fails to meet Dr. Rhoads' requirement that "whatever material is approved for permanent record filming must be equal to or better than the present materials that have been certified for permanent record use."


-Doug
Douglas Nishimura
Image Permanence institute
Rochester Institute of Technology

-----Original Message-----
From: Records Management Program [mailto:[log in to unmask]] On Behalf Of Larry Medina
Sent: Thursday, August 08, 2013 4:21 PM
To: [log in to unmask]
Subject: Re: Quality of CDs

This is a question you'll get a lot of opinions on but no concrete answers.  Most of the definitive studies done are at least 5 years old and depending on who paid for the research, not all that trustworthy.  This is one I cite regularly for those who ask:

http://www.loc.gov/preservation/resources/rt/NIST_LC_OpticalDiscLongevity.pdf


I pretty much tend to ignore anything on any packaging from a vendor- silver, gold, platinum... whatever... if you read the fine print, they all say the same thing... if the disc is stored under OPTIMAL conditions and it fails, they'll give you a new disc.  BIG DEAL... the disc isn't what you've lost!!

For me, it's 3-5 years...tops would be 7.  Generally, applications used to generate the data upgrade about that anyway, so you should open and refresh the files anyway.

Also this guide gives you care and handling info for digital media-

http://www.itl.nist.gov/iad/894.05/docs/CDandDVDCareandHandlingGuide.pdf


Larry
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