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ARSCLIST  January 2010

ARSCLIST January 2010

Subject:

Re: quality of HHB CD-Rs?

From:

[log in to unmask]

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Thu, 28 Jan 2010 08:59:32 -0500

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text/plain (122 lines)

There are a number of reasons why CD-Rs and DVD-Rs fail.

1.  Poor handling.
This can lead to physical damage to the discs. Some damage can be
compensated for by the error correction system, but damage such as breakage
or widespread delamination cannot be repaired.

2.  Wrong storage enclosure.
This relates to poor handling. The wrong storage enclosure leads to
scratching, provides poor physical protection for the disc, and can
chemically interact with the disc.

3.  Chemical degradation.
This is accelerated by high temperature/relative humidity storage
conditions and poor manufacturing. The main concern are the dye AND the
metal reflective layer. Yes the metal reflective layer is very important
and it is not just the dye that determines the stability of the disc. If
the protective layer in CD-Rs is poor or the adhesive used to bond DVD-Rs
is chemically active, then the metal reflective layer can oxidize and lead
to unplayable discs. You can eliminate oxidation of the metal layer by
choosing gold metal layered discs. You can eliminate dye degradation by
choosing the phthalocyanine dye which is very stable to heat, humidity, and
light. These factors will affect cyanine and azo dye discs. However, I do
not see light as an issue unless you leave azo and cyanine dye discs with
the dye side facing up and exposed to a UV emitting source for several
months, 24/7. Obviously, not the best way to store discs. If stored in
jewel cases and on a shelf, light plays no role in the degradation.

4. The discs were never really recorded properly in the first place.
There are many reasons for creating a disc that is not properly recorded
e.g. not finalizing the disc, but I would like to focus on error rate. If
the disc was recorded with a high error rate initially, then failure can
occur quickly. A little bit of chemical change in the dye or metal layer or
some scratching or other damage may push the errors over the correctable
limit and problems or complete failure can occur. If the discs were
recorded with a low error rate initially, the discs have plenty of headroom
to absorb damage before problems become evident on playing.

In the research on optical media that I have performed over the last 10
years, I have recorded many different discs, many different brands, using
many different drives, and at many different speeds. Ten years ago, you
would have compatibility issues - one drive would record a disc with a high
error rate, whereas another drive would record the same brand of disc with
a very low error rate. Nowadays, this is much less of a problem, as almost
any disc burns well in almost in new or fairly new drive. Exception - some
dual layer DVD-Rs. In some recent experiments, some brands could not be
recorded with an error rate below the standard limit or even close to the
standard limit, regardless of recording speed, recorder type, or day of the
week.

From my experience, I believe that the disc failures we hear about are
primarily due to point #4. Unfortunately, in the past, when the propensity
to record discs with high error rates was more likely, no one tested their
recording system (disc brand, software, recorder) before actually recording
discs to ensure that low error rate discs were being produced. It was
assumed that the discs were okay because they could be read right after
recording - not knowing that they did have a high error rate and on the
verge of failure.

So, I would go back into your collections and randomly check those early
discs. Have an error rate test performed - by a company or purchase a low
cost tester. By all means create a backup on hard drive (and back up that
hard drive). However, don't assume that all CD-R and DVD-R are very
unstable and about to be lost forever.


Joe Iraci
Canadian Conservation Institute




                                                                           
             Shai Drori                                                    
             <[log in to unmask]                                             
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             Recorded Sound                                                
             Discussion List                                       Subject 
             <[log in to unmask]         Re: [ARSCLIST] quality    of    HHB 
             >                         CD-Rs?                              
                                                                           
                                                                           
             01/28/2010 12:56                                              
             AM                                                            
                                                                           
                                                                           
             Please respond to                                             
              Association for                                              
              Recorded Sound                                               
              Discussion List                                              
             <[log in to unmask]                                             
                     >                                                     
                                                                           
                                                                           




I don't have the discs on hand anymore but when you asked for info on
them from the burner it would say what glass was used to press them and
what manufacturer. The first ones were definitely Mitsui, the later
batch was if I remember correctly memorex (plasmon). BTW gold or regular
your biggest problem is not the reflective surface but hte dye itself.
UV light from neon lights kills them very early in life, even the higher
end expensive ones. COPY your cd's, even the gold archival ons ASAP. HHB
is not as well known in the US as it is in Europe. Some stuff they make
some they rebrand (like hardware from Marantz, cd's from Mitsui etc.).
Shai

Lou Judson wrote:
> No proof. But common enough knowledge that I never bought any. If not
> outsourced, where was their factory?
>
> <L>
>
> On Jan 27, 2010, at 11:11 PM, Alex Tomlin wrote:
>
>> Worldwide?... Proof?
>

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