(Mentioned this in passing in the thread on CDs skipping in the comments on columns forum–but I think it needs its own thread!)
I wanted to know how long a CD lasts. There was a scary piece in the UK music mag The Wire a few years back giving a ridiculously short lifespan–10 years I think?–but that’s obviously wrong. However, it seems obvious that CDs will eventually deteriorate, as they’re made of plastic and (oxydizable) metal. So when do these suckers self-destruct? I hope not in my lifetime, at least! --N
There was some concern years ago that music CDs would be prone to one problem familiar to users of video laser discs: laser rot. Laser rot occurs when the seal between the two layers of plastic (yes, they’re made in two layers that are pressed together; look at the edge of a CD to see the residue of the gluing process) is cracked or broken, allowing air and moisture to sneak in and oxidize (rust, more or less) the inner layer, where all your valuable data is.
Fortunately, music CDs, being much smaller than the vinyl-album-sized floppy video laser discs, didn’t often get flexed enough to break the seal. And, what with manufacturing of the media getting better all the time, there really aren’t many other natural deteriorative phenomena that’ll affect a CD. So, they oughtta last decades at the very least, unless you’re reckless with 'em.
FWIW: I work in a recording studio, and the CDs we master on (granted, a higher archival quality than normal CD-Rs) are guaranteed to last for 80 years.
Like anything else, it depends on how well they’re taken care of.
The early bird gets the worm, but the second mouse gets the cheese. Delta-9 Home Page
According to my brain (past research, and this has been covered before) the average lifespan of a commercial CD is about 20-30 years. I assume that the usage of such would need to be taken into account.
I could be wrong though, wouldn’t be the first time.
All of the short-term estimates we see giving CDs less than 20 years are
taking wear & tear into account. I believe that CDs will outlive their
owners if properly cared for. Even if the aluminum layer becomes exposed to
the air, aluminum forms a very tough oxide coating which strongly bonds to
the surface of the metal preventing the surface from further exposure to
oxygen and corrosion.
Even if CDs do eventually “decay” for whatever reason, it is much more
likely that years of handling will render your CD unplayable long before it
self-destructs. I take the precaution of backing up my most beloved Cds to
MD, just in case.
As for Chuck’s speckle-lation that CDs may some day give way to a better
format, I don’t see this happening in any time as short as ten years. Even
thought it wasn’t meant for it, minidisc was an excellent candidate for this
(MD was aimed at replacing cassettes). CDs are so easy and cheap to produce
that aol sends out millions of them every year just for people to use as
coasters, make mobiles for the baby room, christmas tree ornaments, etc.
I think the current hurdle is to develope a solid state storage medium for
CD quality sound. That would mean we could get rid of all mechanical parts
involved in spinning a disc, tracking a laser, etc. Songs would never skip
during playback, and the CD would join the 8 track & the dodo.
I don’t know how far along they are with this- but at about 8.8 Mb/minute of
audio, that’s one hell of a memory chip needed to hold Dark Side of the
Moon. If sound purists could ever tolerate ATRAC or any other form of
compression, that 8.8Mb/minute figure would come down.
There was a thread about this a couple of months ago. The lifetime of commerical, pressed CDs is much greater than CDs you burn yourself. In that previous thread, someone with detailed knowledge about it posted a great response, but here’s what it boiled down to:
Commericial CDs are made by pressing a metal (nickel?) disc with a master disc, to create the pits. This is encased with a clear polycarbonate plastic. The metal will last a long, long, time. There was some mention of the plastic absorbing moisture and eventually becoming opaque, but polycarbonate doesn’t do that too much. It would help to store them in the ubiquitous “cool, dry place.” UV light from the sun won’t help, either.
CDs you burn with a CD-R don’t have a metal disc with pits. A green or gold dye is used, and the laser burns holes into the dye. This dye was spec’ed at a 10 year life with CD-R first came out, then a 100 year life dye was introduced. The dye eventually breaks down, and you lose the ones and zeroes. Since accelerated age testing is used (by heating it up, etc.), no one REALLY knows how long they’ll last. It wouldn’t hurt to make a copy every 10-20 years or so, especially since you probably will want to convert any data to a new format that often. How many of you still have the software for your 20 year old floppies? I mean those 8 inch floppy disks, of course!
Arjuna34
Ooh, looks like an opportunity to plug my old college roommate’s research paper. Solid state mass storage is definitely on it’s way, check out this paper on MEMS (MicroElectricalMechanial Systems) Storage: http://www.lcs.ece.cmu.edu/research/MEMS/
It’s under Publications… Very exciting stuff indeed.
That was interesting, although I didn’t see any research paper in the publications link.
It looks like very soon we’ll have a permenant fixture in all of our homes called a memory bank, which stores in solid state RAM every bit of information we currently have on CDs, video tape & zip disks. We’ll simply issue a voice command thustly:
opus: computer?
computer: [Majel Barrett’s voice] working…
opus: load the wide screen version of “Nipple Mania 2000” dubbed in Tagalog, and I’d like to have that in six channel dolby THX, please.
computer: working… [whir… whir… Beep] loaded and ready.
