The Lifespan Of A CD Is Shorter Than We Thought

It probably seemed like a good idea at the time: Instead of fragile paper or clunky disks, why not save your data to a shiny, secure CD? Fast forward a few decades and those CDs (and the data they hold) are suffering from something called "CD rot" — and researchers aren't quite sure why.

Laura Sydell from NPR's All Tech Considered took a trip to the Library of Congress's CD aging lab, where they're trying to find an explanation for the degrading data problem that they've taken to calling "CD rot."Finding that explanation, however, is sending them off in more directions than they anticipated:

Michele Youket, a Library of Congress preservation specialist, plays a CD of classical piano rhapsodies by Erno Dohnanyi. It crackles, and eventually the sound just cuts out.

This is a variant of what's called "CD rot," Youket explains. In this case. it's what's called "bronzing." The outer coating of the CD erodes, leaving a silver layer exposed. And when you leave silver exposed, it tarnishes.

"So it's actually changing the composition, and that's why you hear the scratching there," Youket says.

And here's the thing about CDs: Youket says part of what makes it hard to preserve CDs is that they are not uniform. There were a lot of different standards of manufacturing, depending on the year and the factory.

"This phenomenon of bronzing was particular to only discs that were manufactured at one particular plant in Blackburn, Lancashire, in England," and only between 1988 and 1993, Youket explains.

While the Library of Congress may have the resources to back up their CD-stored data, smaller libraries — not to mention the hundreds of records keeping institutions, governments, and archives around the country — could face a thornier problem.

You can check out the full story over at NPR.

Image: Maciej Bliziński.