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MillimeterArchival DVDs, Part 2 - Good as Gold
Sep 8, 2005 10:46 AM, D.W. Leitner
My last column, "Are DVDs Archival?", seems to have struck a chord with readers, for it prompted a number of e-mail responses.
Michael Relfe wrote to Video Systems editor Cynthia Wisehart:
"Thanks for the great article. Please let D.W. Leitner do a follow up article describing SPECIFIC techniques people use to archive their video data.
Example - Mitsui GOLD DVD-R 4X have a 300 year archival shelf life. To permanently store an archival DVD, burn it to a Mitsui GOLD DVD-R ($1.89).
Put it into a METAL DVD case ($3.00). Put an oxygen absorber packet in the case ($.05) with it. Shrink wrap it in a shrink wrap bag ($.07).
How long is 300 years? Well, if you had filmed that new opera, Almira, by the promising young composer, Georg Friederich Handel, in 1705, and properly stored the results on the type of archival DVD-R Mr. Relfe suggests, you'd need to consider dusting it off and duplicating it again right about now.
Unfortunately, however, no such 300-year archival DVD-R disc exists.
Even if it did, an airtight, archival DVD case would need to be invented as well. Shrink wrap, to my knowledge, is not a long-term archival solution. Cheap shrink-wrap grows brittle as plasticizers evaporate. The vinyl cracks. A breach in air-tightness and the oxygen absorber packet fully oxidizes-this is how oxygen absorption works-rendering the packet equally useless.
Tougher PVC shrink-wrap breaks down with age, releasing acids. Polyolefin shrink-wrap, which contains no plasticizers, is sometimes called archival because it's acid-free, not because of proven durability over decades.
The very thought of a hand-held heat gun aimed at a priceless DVD is alarming to me.
But Mr. Relfe is correct that Mitsui's Gold Archive Grade DVD-R is among the finest archival DVD media available today
Where does the confusion stem from?
Under proper storage conditions, Mitsui Advanced Media (MAM) claims a 300-year archival shelf life for its Gold Archive Grade CD-R product.
However, for its Gold Archive Grade DVD-R product, merely "over 100 years."
What's particularly confusing is that Mitsui's Gold Archive Grade CD-R and DVD-R products rely on identical technologies: 1) a 24-karat, pure gold reflective layer inert to oxidation and tarnish and 2) a patented Phthalocyanine organic dye with the longest lifetime of any photosensitive dye used in CD-R and DVD-R manufacture, according to Mitsui and The National Institute of Standards and Technology.
Remember those golden Kodak Photo CDs? A Kodak study once said that 95% of Kodak CD-R Gold Ultima discs (now discontinued, like the proprietary Photo CD format itself) if stored under recommended conditions-darkness, 25°C, 40% relative humidity--would have a shelf life greater than 217 years.
So when it comes to recordable discs, everyone agrees that gold is good. The underlying reasons for archival DVD's abbreviated predicted life span lie elsewhere, in the facts that:
1) "Due to the organic nature of the dye, degradation and breakdown of the transparent portion of dye layer will occur over a long period of time as a natural process," and
2) DVD pit size and track pitch are each about half that of a CD.
DVDs for this last reason have been called "quad density" compared to CDs. While simple error rate comparisons between DVDs and CDs are misleading--DVD data rates are higher to begin with, and DVD error correction is necessarily more efficient-it should be obvious that all things being equal, such as use of the same Phthalocyanine organic dye for burning data, that block error rates for DVDs would be several times higher than CD on the basis of higher data packing density alone.
Hence the dialing back of 300 years to about 100 years? The two companies which market archival grade DVD-R products with gold reflective layers and Phthalocyanine organic dye, Mitsui (www.mam-a.com/technology/cd/organic_dyes.html) and Delkin (www.delkin.com/delkin_products_archival_gold_dvd.html) both give identical longevity estimates.
What relevance this has to the archivability of upcoming Blu-ray and HD-DVD products is anyone's guess.
Perhaps if archivability were to become a front-burner issue, as it did for fading motion picture prints and negatives 20 years ago and more recently, ink-jet printer inks, breakthroughs would follow. As inspiration and challenge, black & white polyester microfilm is rated at 500 years and color microfilm made with Ilford's direct-positive Ilfochrome (formerly Cibachrome), 300 years.
The italicized statement above concerning inevitable natural degradation of photosensitive organic dye layers is found in a 2004 report published in the Journal of Research of the National Institute of Standards and Technology entitled "Stability Comparison of Recordable Optical Discs-A Study of Error Rates in Harsh Conditions." You can read it yourself at:
http://nvl-p.nist.gov/pub/nistpubs/jres/109/5/j95sla.pdf
Or maybe we could just cryogenically freeze 'em. Anyone thought of that?
(Even if Mitsui's claim of a 300-year shelf life for its archival CD-R, or Kodak's similar claim of 217 years, came with a money-back guarantee--what's a hundred years, give or take--who would be around to know? Certainly not Mitsui or Kodak, which lost $146 million last quarter, announced 25,000 layoffs, and denied takeover rumors. Corporations, like humans and DVDs, rarely survive their first hundred years.)
Another e-mail response to my last column came from Bill Miller, a veteran Director/DP who also writes a production column for Video Systems. He had this to say:
I really found enlightenment in your article on archiving footage. I have 30 storage boxes of 3/4 inch tapes which is the life-summary of my work. I started archiving them to DVD last year and throwing out the bulky tapes which take up a whole wall of my basement. I did make back-up DVDs and kept the really important ones. Now after reading your article, I think I won't throw out any tapes. However, it's getting harder and harder to find parts for 3/4 inch tape machines and if they break you're outta luck. I might just make MiniDV's of everything.
Sign of the times: last week I walked past a 3/4" U-Matic deck put out on the street as trash. I didn't bring it home (inadequate real estate, remember?), but it could have provided Bill with parts.
Next column: is DVD's highly compressed interframe MPEG-2 compression a smart archival choice?
Continue the discussion on “Crosstalk” the Millimeter Forum.
