Q: I’m trying to access pictures on an old CD I made long ago, but can’t. Do they wear out?
A: Few things changed our digital lives like CDs and DVDs, especially when it became affordable to make our own discs.
They don’t “wear out” in the same way a cassette tape or vinyl record used to wear out because there is no physical contact with the recording service, but they do deteriorate.
Anyone that has important files or music stored on CDs or DVDs that they burned themselves may want to get them copied to another storage device before they become unusable.
The companies that sold optical discs boasted life spans of up to 200 years, which gave a lot of people a false sense of security when they decided to use them for long-term storage.
Many variables can dramatically impact the actual life span of all of your optical discs; some you have control over while others are totally out of your control
The biggest variable that you have no control over is the manufacturing quality of the discs themselves, which has proved to have a huge impact on the actual life-span.
Laboratory researchers have done tests comparing discs made by the same company in the same year, wrapped in identical packaging that showed to have dramatically different life spans.
Understanding ‘disc rot’
We also have a couple decades of experience with optical storage, so we’ve learned more about things like ‘disc rot’ which causes discs to become unreadable.
Disc rot can occur from chemical or physical deterioration due to poor manufacturing quality or oxidation from exposure to sunlight, heat and humidity.
Disc rot appears as a discoloration, especially around the edges of the disc or if it’s a poor quality disc, you may start to see delamination or separation of the disc itself.
CDs and DVDs are read by a laser that bounces light off the shiny surface below the clear plastic layer that protects it; oxidation will dull the shiny layer over time, making it harder to read.
Both sides matter
Your recorded information is read from the blank side, but it actually resides just below the label. If you see any scratches of the label that have torn through, the associated data is essentially gone.
If you hold the disc up to a light and can see tiny holes, the shiny recorded layer has begun disintegrating or the label side has suffered damage.
Scratches on the blank side can also cause read errors but if they’re small enough, you may be able to buff them out in a circular motion with a cotton ball or soft cloth and a dab of toothpaste (not a gel).
Store them properly
Much of the damage isn’t noticeable with the human eye, so just looking at the disc won’t necessarily alert you to a problem.
Discs that weren’t stored vertically for long periods of time can suffer minor bending or warping that can contribute to de-bonding of the layers or slight stretching of the recorded layers.
Commercially produced CDs and DVDs can also experience read errors if they aren’t stored properly, so if you value your old discs, take good care of them.
Editor’s note: Ken Colburn is founder and CEO of Data Doctors Computer Services.
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