Re: Re[2]: [AV Media Matters] Polishing of CDs

[lanyap@inlink.com]

Hi Joe,

Thanks for the info.  We use a handle made from a synthetic rubber &
extruded through a die of our design that afforts and applicator that is
both safe & efficient for cleaning shellac, vinyl, acetate, lacquer &
Diamond Discs with the water-based cleaning fluid we developed some 20 yrs.
ago & have marketed for the past 7 years.  A handle similar in size to that
used to clean 45 rpm/7" shellac discs using an optical grade polishing pads
and several drops of our CD Cleaning solution [a modification of our Record
Cleaner] forms the basis of the polishing system.  Though in time we expect
to add media to the system along with a more aggressive pad to offer an
array of choice for dealing with scrattched discs, we have for the moment
focused on the value of improving the poor quality of the original disc
surface for use with pre-rrecorded discs and for use prior to burning
recordable discs.

Please let me know if you'd like to apply these materials to your available
analysis & we'll be glad to forward supplies.  We well know what the audio
& video results are subjectively & know that longterm hard is not done by
the solution & it would be useful to all to know if current techniques can
measure these observations.  Application to high-end audio equipment & new
SACD's also demonstrated an improved presentation.

I look forward to hearing from you.

Duane Goldman

At 08:56 AM 8/10/00 -0700, you wrote:
>E32 refers to the number of uncorrectable errors on the disc.
>
>BLER stands for block error rate and can be defined as the number of data
>blocks
>per second that have one or more bad symbols at the input of the C1
decoder.
>It
>is the most general measurement of disc quality.
>
>The measurements were made with a CDQC2 Compact Disc Test System analyser
>from
>KOCH International.  Discs were tested before and after the scratch
removal.
>
>The analyser tells you what is happening in terms of errors on the disc.
It
>does not tell you specifically how the disc plays.  For example just
because
>an
>audio CD has some uncorrectable errors or high error rate it does not mean
>that
>you can perceive an audible fault.  That being said, the greater the amount
>of
>errors the more likely it is that playability problems will occur either
>immediately or in the future.
>
>Joe Iraci
>Conservation Scientist
>Canadian Conservation Institute
>
>
>
>
>lanyap@inlink.com on 08/10/2000 10:40:56 AM
>
>Please respond to AV-Media-Matters@topica.com
>
>To:   AV-Media-Matters@topica.com
>cc:    (bcc: Joe Iraci/HullOttawa/PCH/CA)
>Subject:  Re: Re[2]: [AV Media Matters] Polishing of CDs
>
>
>
>Hi Mr. Iraci,
>
>Would you be so kind as to briefly define or explain the terms BLER and E32
>& how the measurements are made.  To date we have only subjective
>evaluations showing very positive results with no reports of damage when
>our minimalist polishing system is employed.  We'd be glad to send you
>materials to evaluate in an objective manner upon request.
>
>Thanks for your time,
>
>Duane Goldman
>
>At 07:00 AM 8/10/00 -0700, Joe_Iraci@pch.gc.ca wrote:
>>I have performed some brief experiments on CD polishing as part of the
work
>>that
>>I am doing on the disaster recovery of CDs.  One of the scratch remedies
>>studied
>>was the Fix-a-Disc polishing system.  Scratched and unscratched discs were
>>examined with the results summarized as follows:
>>
>>Read-only disc with no scratches.
>>The disc was unaffected by the scratch removal procedure.
>>
>>Recordable CD with no scratches.
>>The disc showed an increase in BLER (1.8 to 12.9) and E32 (0 to 43494).
>>Also, a
>>3.5 minute portion of the disc could not be analysed at all.
>>
>>Audio CD with significant scratches and playability problems.
>>With the scratch removal the disc got worse: BLER (44.6 to 59.9) and E32
>>(648 to
>>84013).  After a long polishing time all the scratches could not be
>removed.
>>
>>Audio CD with significant scratches and playability problems.
>>This disc showed improvement: BLER (72 to 59.9) and E32 (26332 to 1955).
>>However, deeper scratches were still evident.
>>
>>A fifth disc initially could not be analysed but after scratch removal it
>>could
>>be studied.  However, the disc remained in poor shape with E32 at 10799
and
>>deep
>>scratches still evident.  Polishing the disc for several hours with the
>>highest
>>grit paper could not remove all of the scratches.
>>
>>Therefore, from this small study it is evident that polishing appears to
be
>>hit
>>or miss.  It may improve scratched discs to some degree but may also make
>>discs
>>worse.  This was especially evident in the unscratched CD-R that was put
>>through
>>the process (as a control).
>>
>>Some other scratch removal solutions (plastic polishes, metal polishes,
>>commercially available polishes for CD repair, and others) were also
tried.
>>The
>>results for the mild abrasives were variable as indicated below:
>>
>>Of the 21 discs tested with the various remedies 33% showed no change, 24%
>>showed an improvement and 43% were worse after treatment.  Essentially
half
>>the
>>time the treatment resulted in a disc that was worse off than the
original.
>>Once again scratch removal treatment in this way should be used as a last
>>resort.
>>
>>Joe Iraci
>>Conservation Scientist
>>Canadian Conservation Institute
>>
>>
>>
>h. duane goldman, ph.d.   |   P.O. Box 37066   St. Louis, MO  63141
>lagniappe chem. ltd.            |   (314) 205 1388 voice/fax/modem
>"for the sound you thought you bought"       |   http://discdoc.com
>