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