CD 'rot'

[PeterW]

Hi all,

Yesterday John was doing some clearing out, and came across some old data storage CDs from the days when we used to use Macs, so they must be at least 12 years old. Three or four of them were completely ruined.

They'd been stored in plastic sleeves inside a plastic CD box. When he looked at them, three had started to 'rot', or got a fungus of some sort. I suspect the trouble might have been that the plastic sleeves inside a plastic box stopped them from 'breathing', and the lack of circulating air plus successive changes of temperatures and humidity had done the rest.

Fotunately, what was on the CDs was so ancient - just some old Mac back-up files - it was of no value.

We immediately checked all our later CDs, and fortunately the wallets and sleeves they are in are made from a breathable cloth material, and they showed no signs of deterioration. But we've made sure they're stored with plenty of air circulation round the wallets - just in case!

Here's what one of the Mac CDs looked like.


Food for thought?

PeterW

[kiev4a]

I only store DVDs and CDs in those thin hard plastic cases where theoretically noting touches the disk surface. I have some CDs the date to the Mid 1990s that still are ib good shape.

[doubs43]

I've read in various PC magazines that even the best CD's have a life of about 5 years and should be re-copied before then. That's only what I've read so take it for what it's worth.

I've had music CD's go bad after being in a car for a long while but I expect the exposure to the sun and heat was harsh.

Walker

[mickeyobe]

"... have a life of about 5 years ..."
Do they expire suddenly at the end of 5 years or do they gradually deteriorate?
If, as I suspect, it is the latter then every time it is copied the material 'saved' becomes less and less true to the original.
Eventually it will all be lost.
A sad state of affairs.
Perhaps the industry should concenrate less on bringing out a new model every other day and use their dollars and energies in developing a fail safe storage system.
It may well take a massive class action law suit to convince them of such a necessity.

Mickey

[Reiska]

The quality of a CD/DVD disk depends on the quality of the burner, burner software and the disk itself. In equal storage conditions the rule of thumb is “higher price gives longer data life”.
It is hard to say, which is the most important but the truth is, that on the second-class disk you can not
get first-class results. CD readers can stand a certain amount of errors but understandably the better the start the bigger is the change to stay readable. One of the best brands is Verbatim IMHO.

If the only purpose of use is data storage, most dangerous enemies of the disk are humidity and UV-light. There are also rather big differences in the radiation sensitiveness and mechanical durability.
I think, that the most important factor are storage conditions. Cool, dry and dark are good elements. Some manufacturers are promising over 20 years of “shelf life”

The technique is still new and who knows do we after twenty years (future generations) have suitable hardware for reading the disks , except in the museums. ;D

[John Parry]

When CDs first came out - mid 1980s, they were billed as invulnerable. It took us a year or two to get on board, but my wife purchased a 'Classical' collection of 16 CDs. I put the Tchaikovsky one on after a few years, and it's totally unplayable. Not a mark on it, no scratches. It's just gone. My favourite (Bach) is still going strong, but for how long?

Think that had to be from microbial contamination during manufacture. But that doesn't explain Peter's experience (and I've had one or two that looked like that after getting well soaked for a time). That has to be from microscopic gaps at the centre or edge of the CD that allow water and bacteria or fungus to get in.

Maybe we could try smearing the edge and centre hole with araldite?

Regards - John

[mickeyobe]

" That has to be from microscopic gaps at the centre or edge of the CD that allow water and bacteria or fungus to get in."

I do not know how CD's are manufactured but, if that is the case surely it cannot be such a great problem to properly seal the edges.

Mickey