Gold DVD’s are better than Silver DVD’s…at least somewhat.

Discussion in 'Industry News' started by slackercrurster, Oct 9, 2018.

  1. slackercrurster

    slackercrurster Member
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    Oct 15, 2017
    L.A. - NYC - Rustbelt
    Multi Format
  2. wiltw

    wiltw Subscriber
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    Oct 4, 2008
    SF Bay area
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    Over a decade ago, Kodak engineers did a study of their CDR's that used a fairly conservative methodology. they claimed a lifetime of 100 to 217 years for their CDRs. And they stated that different manufacturers' CDR dyes had widely differing long-term stability. At the same time, CD testing by Kodak had shown that silver is not stable when subjected to life testing at an accelerated pace. Silver discs from six different manufacturers were tested and all failed in less than three weeks.

    One brand of CDs suffered from 'disc rot' in which the aluminized layer deteriorated due to insufficient seal by the lacquer layer. Now, recordable discs don't last as long because of the organic dye used to record the bytes onto discs, which is vulnerable to degradation—particularly in the case of recordable DVDs, which have higher levels of light sensitivity, making them more susceptible to failure.

    Three major dyes have been used in CD recordable media, and their expected shelf life is...
    * Cyanine dye - the cheapest and thus most widely used dye. Looks bluish, blue-green or green depending on the foil backing. Estimatated shelf life: 1 - 5 years
    * Phthalocyanine dye - very light aqua color almost transparent. Usually backed by a gold foil giving it a gold color. Estimated shelf life: 100 years.
    * Azo dye - dark blue in color. Estimated shelf life: 100 years.​

    In the case of DVDs, the actual type of dye used for recordable DVD production varies. And the permanence of the dye varies accordingly. It has been said that those made by Taiyo Yuden were among the most durable. The brand name on the DVD is not necessarily a reflection of the MANUFACTURER of the disc, and has been generally a closely guarded secret by the manufacturer. And in the case of Taiyo Yuden, their CD and DVD manufacturing was apparently sold off to a Taiwan company a few years ago.

    A paper published in 2010 by a joint armed forces study on data permanence mentions that with proper handling and storage,
    a. ―Pressed discs (the kind that movies come on) last … anywhere from 50 to 300 years.‖
    b. ―DVD-R and DVD+R discs are expected to last anywhere from 40 to 250 years, about as long as CD-R discs.‖
    c. ―The erasable formats (DVD-RAM, DVD-RW, and DVD+RW) are expected to last from 25 to 100 years.​

    it also talks about CD (not mentioning DVD) permanence:
    "d. For archival purposes, a phthalocyanine (photosensitive) dye polymer, a gold or silver alloy metallic reflective layer, and a secondary protective coat of resin are the best combination. With this in mind, a recent search found, for example, the Mitsui Archive CD-R Standard Gold disc at about $1.40 each. Also, Kodak offers the Kodak CD-R Ultima Gold disc that their testing has shown to last over 100 years. This disc has the less desired layer of cyanine dye, but comes with the gold reflective layer. The cost of these discs is about $0.30 each."
    Repeated tests have shown that 95% of Kodak writable CDs will have a data lifetime of greater than 200 years if stored in the dark at 25°C, 40% relative humidity (RH).

    The paper goes on:
    "Current optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM, use a red laser to read and write data, while Blu-ray uses a blue-violet laser"​

    "Blu-ray disc manufacturers warranty discs from 50 to 200 years. A new media type may emerge before a disc goes bad, but the long warranty periods show the confidence that Blu-ray manufacturers have in their discs. For example, the Delkin company claims to have the longest archival lifespan (200 years) for their Archival Gold® Blu-ray recordable media."

    But back to the test that was linked...optical discs use organic dyes, and generally organic dyes deteriorate with exposure to light. That's what result in color film and color print changes in color balance! For the tester to assume otherwise (dye fade) due to prolonged exposure to sunlight is not very realistic. Nonetheless it will be interesting to follow the results of further testing by him.
    Last edited: Oct 10, 2018
  3. Billy Axeman

    Billy Axeman Subscriber
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    Aug 18, 2017
    I have used CD's and DVD's a lot in the past but I don't trust them. All my (backup) data is now on small USB drives. They are cheap, reliable, convenient in use, and a lot of data can be stored in a small space.
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