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**Dr Mordrid** · 2 January 2001, 21:43

Kodak says the following about their CD-R media;

"figure 2 shows that with 95% confidence, 95% of the population of KODAK Writable CD Media will have a data lifetime of greater than 217 years if stored in the dark at 25°C (77°F), 40% Relative Humiditiy."

TDK says of their CD-R media;

"manufacturers of phthalocyanine media can spec their discs at 100 years, we spec a minimum of 70 years."

So, if you store your CD-R's in a case where the recorded side is in the dark (as most crystal case liners do), at room temp or lower and in a reasonable humidity the disks will outlive you.

And don't forget: since they are digital media they can also be perfectly copied to whatever superior media comes along OR you can just dupe them every 20 years or so to re-start the clock.

Dr. Mordrid

[This message has been edited by Dr Mordrid (edited 03 January 2001).]

**Biker** · 3 January 2001, 06:06

Thanks Doc - you really put my mind at rest.
But I must say I have heard many tales of CD-R media 'packing up' after a short while.

Is this because they are being 'used' frequently and the laser gradually erases them?

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**wkulecz** · 3 January 2001, 07:31

I've had two day old audio CD-R "pack up". The media is far more easily damaged by scratches, and in this particular situation I think a specular reflection of direct sunlight killed a CD-R as I was putting it into the cartridge of my wife's car CD changer -- I had just played it inside, and as I put it in the changer I saw a flash of bright light reflected from it, and it never played again.

CD-R are so cheap I only use my original audio CDs to make the copies I play -- just like I generally only used my phonograph records to make tapes to listen from.

If you've valuable digital data I'd make a minimum of two copies on two different brands of CD-R media (make sure you get ones with two different dyes)

I wouldn't put my only copy of anything on CD-RW media.

Audio CD are "digital" but they don't generally have the "perfect copy" ability we demand for computer files. The error correction on audio CDs it designed to keep defects from being heard -- not to insure a perfect byte stream.

--wally.

**Dr Mordrid** · 3 January 2001, 07:33

No, the laser doesn't erase them It's not powerful enough to do that in read mode.

The problem is usually scratches on the surface of the CD or exposure to bright light (sun etc.) that damages the dye layer. The fix is easy: make a backup disk and put it away as an archived master.

Dr. Mordrid

**Elie** · 3 January 2001, 08:26

I would say if the CD lasts you more than 20 years, thats good enough.
By then we'll probably have 40 gig HDTV DVD's that the average person can efford.
So for now archive to CD, and when the above technology or something close to it becomes available, convert those CD-R's to DVDs

Even now they say music CD's will become obsolete because it is limited to 44khz 16 bit, they say 48khz 20bit or higher audio will become the standard, and it won't fit on the average CD. So they will have to resort to DVD's for audio instead which of coarse has so much more potential aside from audio quality.

Cheers,
Elie

[This message has been edited by Elie (edited 03 January 2001).]

**Dr Mordrid** · 3 January 2001, 10:16

I don't think improved quality will matter much since most people don't have the perfect pitch it would require to tell the difference. What will matter to them is more music on a single piece of media.

IMHO what's going to fill this slot is MP3-CD. Up to 253 songs (depending on length & encoding) on one CD and they can be organized into directory structures 8 folders deep.

My son has a Kenwood Z919 AM/FM/CD/MP3 player in his Dakota pickup and it works great. AIWA also makes one. He has his music sorted to folders with high quality encoding at about 120 songs/CD-R. His DVD player also plays them so he can create his own party disks according to what group he's entertaining. He loves it and his friends are already looking for their own MP3-CD players; portable, auto and home.

This isn't too hard in this area since in the last three weeks I've seen at least 12 different set-top DVD players and a couple of CD changers in stores that can play them. I've even seen a couple of portable CD players with the MP3 feature.

Looks like a trend to me....

Dr. Mordrid

[This message has been edited by Dr Mordrid (edited 03 January 2001).]

**electric_android** · 3 January 2001, 10:59

Over the last couple of years I've found the white topped CDR's to be the most reliable. Some of the silver/gold plain cdrs tend to flake thus redering them usless.

TDK CD-R74 reflex and Infinite discplanet 74/80 white tops have v.reliable

Paul

**wizz** · 4 January 2001, 03:12

wkulecz

I don't think specular reflection of light could damage your CD-R at all. The most it would do is split the light up into its constituent colours. The bright light you saw was probably just a reflection and something else damaged the CD-R.

I used to work as an engineer for a CD pressing company, they found that the medium is mostly damaged by scrathes and chemical spills, i.e corrosive or acid drinks (coca cola anyone?), but if perfectly stored decomposition of the surface material is very slow over the persons lifetime, so they should last over 100 years.

**Elie** · 4 January 2001, 07:53

I've had bad experience with blue CD's, basically if I burn an audio CD, it won't work in selected CD player or Car audio systems.
I personally like Silver/Gold or green, they all burn nicely and play anywhere.
Now in terms of which one lasts longer, I would say it all depends on which material lasts longer without oxidization, Hmmm maybe Gold will last longer??

Any comments?
Elie

**wkulecz** · 4 January 2001, 07:58

"Should last 100 years" is a claim.

I can only report my one experience where a perfectly working audio CD-R was removed from one player, hand carried, never put down anywhere and inserted into another where it wouldn't play. It then wouldn't play when reinserted in the initial player. The only "event" was a few seconds of exposure to bright sunlight.

Given that I've burned about 200 CD-R and experienced 1 catastrophic failure, that is 2.5% chance of losing your data that I've observed in my (limited) experience.

I used the "split the light into its component colors" effect to look for scratches or defects on the recordable side. There were no scratches. I noticed a small ~1cm circular irregularity that appeard to be in the dye layer on the outer third at one spot on the disk. Was this caused by the sunlight or a manufacturing defect? How can I tell? Do I care? Fact is, it played but later became un-playable with no physical mishandling other than a bit of direct sunlight.

I've never yet lost data on CD-R except for some Direct CD or EZCD Creator screw-ups I had the misfortune of using these well before some serious bugs were fixed. CD-RW media is a whole 'nother story. I stopped even trying them for anything other than VCD or SVCD to try in standalone DVD players.

--wally.

**Biker** · 4 January 2001, 08:32

OK I feel I must explain why I care and why it matters to me so much.

I create virtually all my own music, video, and various other artwork etc. Many computer programs and store family history as well.

I back all this onto CD-R and felt secure until the stability/damage thought occured. Obviously the value and nature of my data is priceless, and as you can well imagine totally irreplaceable.

I wouldn't care at all if it was just copying other peoples work - music/video etc. either. But as you can see this is a very important topic for anyone that has unique pieces of work to preserve.

So keep the info/feedback/experiences coming in please. - Many thanks.

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**wkulecz** · 4 January 2001, 13:45

Biker,

In your situation I'd back up your data to all three (or four) different dye fomulations. The cost of the blanks is trivial. Make at least one copy to each gold, silver, and blue media and store in "jewel box" CD cases.
www.cdspeed2000.com has some links to error rate data for different CD-R media.

Be ready to recopy to the next new thing (like DVD-R) so you don't find yourself 30 years from now scouring antique stores in search of a working computer with CDROM drive to read them :-)

--wally.

[This message has been edited by wkulecz (edited 04 January 2001).]

**KRSESQ** · 4 January 2001, 14:06

I think it's reasonable to assume that the CD/DVD disk format could survive at least 30 years, for the same reason the 3 1/2 inch floppy has hung around so long: it's compact and easy to use, reasonably durable, inexpensive, and there are MILLIONS of the damn things out there!

The players will probably be able to read/write >1200 GB to a single disk by then, and still play the old CDs, and guys like us will STILL be demanding more capacity!

Wally: If you burn 200 CDs and lose one, that's a 0.5 percent failure rate, not 2.5 percent (this coming from the guy who flunked high school algebra).

That's a failure rate I can live with.

Kevin

P.S. I remember, when CDs first hit the market, the manufacturers claimed you'd be able to use them to play Frizbie with your dog without damaging them!

[This message has been edited by KRSESQ (edited 04 January 2001).]

**Biker** · 4 January 2001, 17:25

Very useful info chaps thanks.

Any comments on Gold, versus Silver, versus 'blue' coloured CD-R's, as regards to wear and tear etc. PLEASE?

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