Re: [ARSCLIST] The ways CD's and DVD's can fail.

[Jerome Hartke <jhartke@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx] On Behalf Of Mike Richter
> Sent: Thursday, December 07, 2006 10:41 AM
> To: ARSCLIST@xxxxxxxxxxxxxxxx
> Subject: Re: [ARSCLIST] The ways CD's and DVD's can fail.
> 
> Charles Lawson wrote:
> > Ronald Frazier writes:
> >> I honestly think the MAM-A Gold discs are the best in the world at this
> >> time
> >
> > I, too, still have the best general results with these discs.  However,
> > quality control on MAM-A gold discs continues to be an issue for me and
> > the problem is growing worse.  I am now averaging five discs per pack of
> > 25 that arrive with debris, fingerprints or oily smears on them when
> they
> > come out of the shrink wrap.  I have begun a collection of bad discs to
> > return to the factory.  The fingerprints should make tracking the
> careless
> > party pretty simple...
> >
> > Visually inspect all discs before you plop 'em in your drives...
> >
> > Caveat emptor,
> >
> > Chas.
> 
> My experience with faulty discs is almost exclusively due to attempts to
> rescue those sent or discussed by others. It appears that the most
> common reasons for disc failure are mishandling and poor original
> recording. In time, the instability of the dyes will come into play, but
> a well-recorded CD-R treated with reasonable care will surely last a
> decade and presumably many decades. I know that error rates do not
> increase noticeably over a decade because I have recordings I made in
> the early and mid 1990s which test today as they did when freshly
> burned: no recognizable increase in C2 errors.
> 
> Mishandling takes many forms. Solvent-based markers are known to leech
> through the acrylic lacquer atop the disc; the data lost cannot be
> recovered and often enough the disc will not stabilize in a drive to
> permit sector-level recovery. Some dyes - notably the cyanine and
> phthalocyanine which are otherwise desirable - are more sensitive to
> light and possibly to heat than others; exposing discs with them to
> sunlight for a few hours bleaches out the information. Scratches can
> also be significant, but if severe are easily buffed out.
> 
> Poorly recorded discs are vastly more sensitive to failure over time
> than those recorded with low error rate. In an attempt to get 'better'
> recordings, many are writing at speeds below the optimum for a given
> medium and drive with results as unsatisfying as writing above the
> 'sweet spot'. For archiving, it seems to me essential that each batch of
> blanks be tested to determine optimum recording conditions and quality
> to be expected when they are used.
> 
> It is my advice to those seeking personal archives to consider practical
> issues such as those above before choosing to invest in high-price
> blanks. MAM-A gold may have better life under ideal conditions than a
> high-quality silver disc, but if it is not as well written in your
> drive, the advantage will be lost. At best, the improvement is not
> enough to take shortcuts in other aspects of good practice; one should
> still make two masters on different media to be stored separately. In
> the real world of finite resources, the choice of medium is only one
> factor in the expected life of an archived disc.
> 
> Mike
> --
> mrichter@xxxxxxx
> http://www.mrichter.com/

Mike is on target as usual. For details, see our white paper on causes of
CD-R failure at http://www.mscience.com/cdrfail.html

Jerry
Media Sciences, Inc.