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What sort of media to buy????you will be interested

Discussion in 'CD-R(W) Media' started by ejm, Oct 25, 2003.

  1. ejm

    ejm Guest

    This is an article from Austalian Personal Computer Magazine coming out in November. It made me sit up and take notice, maybe you will to.

    [bold]CD-R’s unreadable after two years[/bold]

    If you thought CD-R's were the safest way to archive precious family photos, think again.

    New test results reveal that CD-R discs can become unreadable in under two years, with some manufacturers using cheaper materials to cut costs.
    Researchers burned hundreds of discs from 31 manufacturers (16 each) in November 2001 and re-tested them 20 months later. They were stored in a closed cabinet and used only once.
    "Three brands had severe ageing problems," said lead tester Jeroen Horlings, of Dutch PC Active. 'Two were still readable - but for now long? And one was only partially readable!'
    The discs were tested with a CD Associates CIDA3000, a high-end analyser used in the CD manufacturing industry.
    Horlings said the three bad brands, all Dutch generics, have an exceptionally high error rate corresponding with the location of logos and other graphic elements printed on the disc.
    The research report stated the most reliable brands are Memorex, Parrot, TDK, Sony, Fuji, Verbatim, HP, Acer, Octron and Maxell.
    Verbatim Australia managing director Merv Tabe said cheap generic CD-R's often have porous lacquer layers on the top that allow salt to penetrate through to the silver reflective layer, causing oxidisation. It's possible that, in the Dutch case, the label stamping had damaged the lacquer layer, making it easier for oxidisation to occur.
    Although Verbatim continues to make healthy profits because of its ownership of all stages of the CD-R manufacturing process, the industry is generally troubled by consumer expectations of cheaper media costs, Tabe said. Where CD-R's were once made with a true gold metal layer (which doesn't oxidise), it manufacturers can no longer afford to use it due to consumer pressure for cheap disc.
    "Unfortunately the reflective layer issue has become clouded. Some brands call their product gold, but the reflective layer isn't gold - it's gold printing on the top layer and not actually the metal gold," said Tabe.
    There are many reasons why poorly manufactured CD-R's can fail, he said, including the fact that most manufacturers are using low cost pthalo-cyanine ink from a single chemical manufacturer. As manufacturers responded to the ever-increasing speed of CD writers, they had to cut ink thickness, making the recording layer more vulnerable to the tiniest amounts of degradation. "Media dye deteriorates by UV light - after all, it is a light-sensitive dye. We have even found that just by reading the disk, the laser causes the dye to deteriorate!'
    Recordable DVDs are even more susceptible to deterioration because of their significantly higher track density, he said. Some manufacturers are using dye without paying royalty fees, and leaving the dye manufacturer ID off the disc's inner-tracks. As a result, CD writers use the wrong laser power for writing to that particular type of dye.
    "It's tough for the consumer to find who is truly an original manufacturer. Some of the top brands out there are just that: branded," said Tabe.
    Factory-made CDs have pits pressed into a layer of aluminium, based on a molded master. CD-R discs use an organic dye layer in front of a reflective layer to simulate the pits found in a pressed CD. Heat from CD writer lasers can break down chemicals, causing a slight change in reflective quality.
    The process doesn't "burn" the dye, rather the chemical change is only very slight. In many cases users won't notice that a disc is failing or damaged, due to the CD format's extensive error correction data, according to Tabe. About 30% of the data on a CD is Cross- Interleaved Reed-Solomon Code (ECC) data. Various attempts have been made to reduce it, and in 2002 Sanyo announced a format that packs 1.4GB onto a standard-sized CD by reducing the ECC component 10% of the disc.
    However, as the Dutch PC Active's disc durability findings show, error correction data is tremendously important, especially on CD-R's.

    Dan Warne
  2. tigre

    tigre Moderator Staff Member

    Feb 18, 2003
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    Interesting read. Thanks.
  3. piano632

    piano632 Regular member

    Nov 20, 2002
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    This must be a joke!

    Mitsui still makes real gold-layer discs, but why is gold necessary? Pressed CD's use aluminum.

    I have often believed that higher speed discs were less reliable than lower speed ones (common sense to me), but now I have proof from this article.

    Moral of the story: Don't use cheap generic media. Don't use discs rated at over 24x speed. And make backup copies of anything important!
  4. magnetic

    magnetic Regular member

    Aug 5, 2003
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    looks like scare tactics to me,
    i used to make the cd-r's so I have a good idea what I'm on about.

    If you read it again looks like you don't wanna buy Dutch CD's

    oh and,
    Factory-made CDs have pits pressed into a layer of aluminium, based on a molded master
    not likely, it's usually a nickel stamper in the moulding machine as heat and pressure is applied when making a cd and the Aluminium would crumble to pieces.
    Aluminum is used on the real audio cd's, the ones you'd buy in a record store, as the reflective material.

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