Blu-ray Disk Longevity? - AVS Forum
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post #1 of 16 Old 01-12-2006, 10:13 PM - Thread Starter
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Recently, a German recording expert stated that due to unstable dyes in the recording base of burned CDs and DVDs, that they would not be readable beyond 2 to 5 years. Claims counter to this have been made by several manufacturers. Verbatim flatly says on their website that properly made recordings on their disks that use an advanced type of dye in the recording layer, can last over 100 years.

Since the tiny pits made by blue-lasers to carry the digital recording, are much smaller than those from red lasers, durability could be an even greater problem. With smaller burned pits, any change in their shape would have an even greater effect on their readability.

Is their any unbiased information about the nature of the recording base material for blue-laser disks? Would the manufacturers care if we had to buy all new blank disks and pre-recorded movies every couple of years? Could metal disks be used for write-once blue-laser DVDs? Would we be willing to pay a lot more for them, if they had a longevity that was extended 10 or 20-fold over disks with dye-based recording layers?

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post #2 of 16 Old 01-13-2006, 07:02 AM
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Well, first you have to understand that the dyes used in consumer burned media are not the same as those used in professionally reproduced disks. I purchased my first CD back in 1987 and it still works today. That's almost 20 years ago.

As for the longevity of burned media, I have burned disks and even have blank media that are approaching 9 years old that are all still good. And these are not disks that were treated with kid gloves. Maybe the dye used in my discs is special, but back then I was buying whatever I could find cheaply.

On the blue disc front, I think it's still too early to tell. UDO discs are similar to Blu-Ray, and they claim a conservative 50 year lifespan for their media stored in optimal conditions (low humidity & light), but they're also a cartridge based optical media. I'm still trying to get information on the dye used in the media.

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post #3 of 16 Old 01-13-2006, 08:24 AM
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It would be nice to have media last for a 100 years!

But how do you test for something like that, what conditions makes the dye fail. I have had media that failed in one year. Also does any of the manufactures state what test and procedures they use in these tests.

Then you have to take into account the environment conditions of the average user, I am of the belief that these companies over state the life of their media. I still would make a backup of a backup, and then every couple of years verify its condition, if degradation is shown backup again.

Since Blu-Ray uses some of the same techniques as other optical media, I would also be very skeptical about any claims people made.

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post #4 of 16 Old 01-13-2006, 09:48 AM
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Typically, when claims are made of numbers like "100 years", they are based on some kind of acceleration factor.

For example, some (most, actually) polymers degrade with age and exposure to the environment. If you lay a graph of age vs. [some property, let's say tensile strength] next to a graph of the same data taken at elevated temperature, both graphs will be nearly identical, but the high temperature will accelerate the "aging process" and result in a "compression" of the time it takes for the material to degrade.

So if the material properties are well-understood, and the mathematical relationship between the temperature and the degradation rate vs age are quantified, you can run tests at elevated temperature and compress 100 years of aging into a month or so. This has been very effective in the plastics industry, and in other industries (semiconductor being one I understand well).

The trick arises when the material properties are not well understood, and assumptions about the temperature behavior are made based on theory or on insufficient data. Honest engineers will release those kinds of numbers based on theory, if they must, but will always keep a "real-time" graph going as the years progress in order to compare the theory to the reality.

Of course, by that point, people have already made the purchasing based on what Marketing told them would be the useful lifecycle of the product, and since everyone involved is generally dead or in another job by the time the graceless failure occurs...

Sorry about the lecture. I was feeling wordy.

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post #5 of 16 Old 01-15-2006, 04:51 AM
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If we are talking now about dye or phase change based discs (DVD+/-R and RW, and their next gen HD recordable counterparts), then there is very little reliable, scientific 3rd party data.

NIST did a study of DVD-R/+R discs in 2004 and found out that most of them do not stand well in accelerated aging tests.

A person living in Singapore (hot & humid environment) has found out that his DVD+R and -R discs have destructed in less than a year. Humidity appears to be the main culprit in accelerating data loss for his discs.

Now, what is the longevity for Blu-Ray and HD-DVD discs?

Assuming similar dye, similar reflective layer materials and equal quality bonding, the longevity could be somewhat similar. Note, this is only for recordables! Pressed discs have totally different composition and when done properly should last much longer (as pressed cd and dvd discs have demonstrated).

How long will the Blu-Ray and HD-DVD recordables last?

The jury is still out even on dvd recordables. More studies are needed.

However, it has been clearly shown that even so-called 'quality brand' discs can fail in less than a year, if the environment is humid enough. It is unknown how well DVD discs tolerate UV radiation, temp changes, noxious gases, ozone and changes in pH of surrounding environment.

Data from CD-R studies suggest however that disc materials can be susceptible to attacks from various environmental factors.

So, don't go storing all your unique precious data only on single optical discs, be they DVD or Blu-Ray, until more accurate data is available. Have multiple backups, use tape if possible, store properly and re-check quality of backups periodically.

Good data (NIST study) already suggests that phthalocyanine/gold based CD-R disc formulations can stand aging test very well and their longevity should be sufficient for consumer purposes when stored properly. Such discs are currently manufactured/offered by MAM-A (Gold archival, 300 year rated version) and Prodisc (Prodisc Reference Gold Archival). This is not a guarantee of the quality of their products, but a statement of the fact that they use phthalocyanine dye and gold reflective layer, which have been found out to be highly stable. I'm not affiliated with either company.

I'm looking forward to testing on Blu-Ray and HD-DVD recordables and esp. their longevity, as the discs and burners become more widely available (and cheaper).

regards,
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post #6 of 16 Old 01-18-2006, 07:03 AM
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Pardon my ignorance .

I have wondered about these issues for a while.

Please correct me if I am wrong on the following points

1. Pre-recorded DVD movies are burnt onto a thin layer of aluminum sandwhiched between 2 layers of polycarbonate. NO DYES ARE USED

2. Blu-ray pre recorded movies are burnt on to a thin layer of aluminium. No dyes are used

3. HD-DVD pre-recorded DVDS are burnt onto a paper matrix via dye. This paper is sandwhiched between 2 layers of polycarbonate.

It was point 3 that turned me off from Toshibas format.
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post #7 of 16 Old 01-18-2006, 07:26 AM
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Blu-Ray is the format capable of using paper, not HD DVD.
http://www.newscientist.com/article.ns?id=dn4894

Here's a wider Google search:
http://www.google.com/search?hl=en&q...+made+of+paper

Care to reconsider?
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post #8 of 16 Old 01-18-2006, 07:41 AM
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Fascinating , and there I was thinking Toshiba was the papermate!

But is the MOVIE itself actually encoded via dye on paper???
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post #9 of 16 Old 01-18-2006, 07:47 AM
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From the New Scientist article: "Data is stored on Blu-Ray disks in the form of tiny ridges on the surface of an opaque 1.1-millimetre-thick substrate. This lies beneath a transparent 0.1mm protective layer." No mention of dyes being used.

I'm guessing the advantage to paper-based discs is that it drives down the cost to produce them, but what are the objections to paper-based discs? I thought this was a cool idea when I first heard it, but I've been wrong before.
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post #10 of 16 Old 01-18-2006, 07:52 AM
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I just thought that Aluminum was a more robust substrate to put your movies on (if that is actually how current DVD's are made). Apparently the pits are etched into the alumium by laser and are not suspect to the ravages of time. I don't know that's why I'm asking.

I was just wondering about my blu ray / HD-dvd library 20 years from now- how will the paper hold up.

I have no funadamental objection to paper itself. It just seemed like a cheap way to do things

If its true that the recording layer of blu ray discs will be made from paper I might quickly become enamoured of the Toshiba format
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post #11 of 16 Old 01-18-2006, 07:56 AM
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The knock against aluminum is that it oxidizes over the years, although I still have CDs from 1987 that are fine. I'm not sure how paper discs will hold up, but it's not entirely made of paper-- only 51% of it is. I'm sure it's mixed with other sturdier material to stabilize it.
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post #12 of 16 Old 01-19-2006, 03:49 PM
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Quote:
Originally Posted by Steve McD
Recently, a German recording expert stated that due to unstable dyes in the recording base of burned CDs and DVDs, that they would not be readable beyond 2 to 5 years.
He must have either been quoted out of context, or he's an idiot, as that's just wrong. Actually, I think that article was some kind of practical joke, to see how gullible people are, as it's been reposted and quoted everywhere.
Quote:
Originally Posted by JosephShaw
Well, first you have to understand that the dyes used in consumer burned media are not the same as those used in professionally reproduced disks.
First you have to understand that mass produced DVDs aren't burned, but pressed. The pits are physical, not dye. I couldn't tell you exactly how BD will be produced, but in general the issues that affect burned media are entirely different. So this thread only becomes meaningful once they introduce burnable BD/HD DVD

Whether there will be issues with coating, scratches, delamination of studio produced discs is another question, different issues entirely.
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Originally Posted by Rthoreau
It would be nice to have media last for a 100 years!

But how do you test for something like that, what conditions makes the dye fail.
Government and manufacturer labs have developed standards for testing, based as archibael suggests on knowledge of the chemistry of the materials used; while they are still simulations, they are meaningful tests. Whether the time frames are exactly right, they definitely show that different media and different storage condition lead to very different rates of failure. That is, there are good blanks and bad blanks; and good ways to store them and bad ways to store them.
Quote:
Originally Posted by Halcy
If we are talking now about dye or phase change based discs (DVD+/-R and RW, and their next gen HD recordable counterparts), then there is very little reliable, scientific 3rd party data.

NIST did a study of DVD-R/+R discs in 2004 and found out that most of them do not stand well in accelerated aging tests.
I don't think that's the right conclusion to draw, we all know most of the media out there is cheap and lousy. (But there are times when that's fine - for copying files to take on a business trip, or to bring home, you don't need 100 year media). The right conclusion is - if you want them to last, it's worth buying decent media, and taking some care in how you store them.

More links and discussion here:
http://forums.etree.org/viewtopic.php?t=6740
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post #13 of 16 Old 01-19-2006, 04:05 PM
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Quote:
Originally Posted by bferr1
what are the objections to paper-based discs? I thought this was a cool idea when I first heard it, but I've been wrong before.
The issue would be whether you have materials that degrade rapidly over time, especially if you use them in what people might consider to be a normal way (put them in your car in the summer time).

If either format has serious quality problems (new discs not reading, or discs failing soon), you'd have to think that could have a big effect on adoption.
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post #14 of 16 Old 01-19-2006, 04:08 PM
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I'm no chemical engineer, but I suspect that aluminum as it is implemented in pressed disks would not be prone to oxidation. Aluminum is highly resistant to oxidation as is, but you have to remember that it is encased in plastic, which I doubt allows much (if any) oxygen transfer. Then again, I'm no chemical engineer, but I'm sure that someone on this forum probably is.
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post #15 of 16 Old 01-19-2006, 04:13 PM
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Currently, the aluminum doesn't have the data in it, it's just there to help reflect the light. The data is molded/pressed into the plastic.

Here's a summary of DVD replication as it now stands:
http://www.fastcdcopies.com/Replication.htm

Here's an article on how the new discs will be made. Both discuss creating masters, so presumably the stamping/molding process is similar to current methods:
http://www.medialinenews.com/article...icle_831.shtml

As far as BD recordable media - there's some info at these links, vague but it might give you a general drift:
http://www.blu-raydisc.com/top/About...cle-14910.html

http://www.blu-raydisc.com/top/About...cle-14861.html

Both make claims about the stability, so clearly they are on the case. No surprise there.
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post #16 of 16 Old 01-19-2006, 09:00 PM
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Quote:
Originally Posted by c.kingsley
, but I suspect that aluminum as it is implemented in pressed disks would not be prone to oxidation. .
I agree and that's why Im holding out for the new Jaguar XK


Thanks Buzzy for that illuminating info- I had no idea the data was recorded in the plastic
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