Re: [ARSCLIST] New CD Report NIST

[Joe_Iraci@xxxxxxxxx]

BLER is a good indicator of change occurring within the disc with
accelerated aging.  The way in which it changes with aging makes it a
useful tool compared to other parameters.  As Mr. Hartke has mentioned,
there are other quality indicators as well that should be examined since
BLER can occassionally be misleading.

I compare BLER to the folding endurance test that is used extensively in
the paper field.  The folding endurance test is very sensitive to changes
occurring with the paper, but the measurement does not allow you to
pinpoint the source of the changes.  I believe BLER compares to this very
well.  It is its senstivity to changes occurring in the disc that make it
useful.

Joe



             Jerome Hartke
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             13/12/2004 06:42
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I believe that Kodak and TDK may have published information long ago, but
that was all based on BLER. Other than that, Google would be a good option.

Jerry

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx] On Behalf Of Steven Smolian
> Sent: Monday, December 13, 2004 5:56 PM
> To: ARSCLIST@xxxxxxxxxxxx
> Subject: Re: [ARSCLIST] New CD Report NIST
>
> This is a question for Mr. Hartke:
>
> Apart from your own report on CD testing, can you suggest a readily
> available web source which discusses the same issues, preferably one
which
> does not come from a professional testing service?
>
> Steven Smolian
>
> ----- Original Message -----
> From: "Jerome Hartke" <jhartke@xxxxxxxxxxxx>
> To: <ARSCLIST@xxxxxxxxxxxx>
> Sent: Monday, December 13, 2004 3:14 PM
> Subject: Re: [ARSCLIST] New CD Report NIST
>
>
> > As mentioned before, BLER alone gives misleading results for
accelerated
> > aging as reported at http://www.mscience.com/longev.html
> >
> > Jerry
> > Media Sciences, Inc.
> >
> >> -----Original Message-----
> >> From: Association for Recorded Sound Discussion List
> >> [mailto:ARSCLIST@xxxxxxx] On Behalf Of Joe_Iraci@xxxxxxxxx
> >> Sent: Monday, December 13, 2004 10:07 AM
> >> To: ARSCLIST@xxxxxxxxxxxx
> >> Subject: Re: [ARSCLIST] New CD Report NIST
> >>
> >> I have performed a similar study that will be published in Restaurator
> in
> >> early 2005 (I will pass on the reference to the list once it is
> >> published).
> >> Accelerated aging was performed on CDs, CD-Rs (various dye types),
> >> CD-RWs,
> >> DVDs, DVD-Rs, DVD-RWs.  Many (much more than the NIST study) different
> >> types from different manufacturers were tested.  Results were based on
> >> BLER
> >> changes.  Conclusion was that the CD-R with phythalocyanine dye
> >> outperformed all other disc formats.  A relative stability ranking of
> the
> >> various formats was produced.
> >>
> >> The goal of the study was to assist individuals in making choices when
> it
> >> comes to optical media.  Making a  lifetime prediction is time
> consuming,
> >> expensive, and usually contains a lot of uncertainty.  I believe a
more
> >> practical approach is examining relative stabilities.  Any study that
> >> provides information on how this media reacts is useful.  Granted
> >> reactions
> >> are occurring at higher temperatures and there is no guarantee that
> those
> >> same reactions will occur at room temperature, but if you had to
choose
> >> would you trust media that withstood harsh accelerated aging (80
> degrees
> >> Celsius and 85% relative humidity for intervals up to 84 days) and
> still
> >> had no E32 errors and low BLER or media that failed within the first
21
> >> days under these same conditions.
> >>
> >> Yes, there are other factors to consider like writing speed and
> >> compatibility issues, but the focus is on media stability in this
case.
> >>
> >> In the above study, using either BLER or E32 errors would have led to
> the
> >> same conclusions.  BLER alone can sometimes be misleading, but
> generally
> >> not when it comes to monitoring degradation via accelerated aging.
As
> >> long as both are monitored I do not see a problem using BLER. This
> >> observation is based on the experience of aging and analyzing several
> >> hundred discs.  Same applies to PI errors for DVDs.
> >>
> >> Joe Iraci
> >> Senior Conservation Scientist
> >> Canadian Conservation Institute