If you've tried listening to any of your old CDs lately, if you even own them anymore, you may have noticed they won't play. That's what happened to mine, anyway.
CD players have long since given up on most of the burned mixes I made in college. (In some cases, this is for the best.) And while most of the studio-manufactured albums I bought still play, there's really no telling how much longer they will. My once-treasured CD collection—so carefully assembled over the course of about a decade beginning in 1994—isn't just aging; it's dying. And so is yours.
"All of the modern formats weren't really made to last a long period of time," saidFenella France, chief of preservation research and testing at the Library of Congress. "They were really more developed for mass production."
France and her colleagues are trying to figure out how CDs age so that we can better understand how to save them. This is a tricky business, in large part because manufacturers have changed their processes over the years but won't say how. And so: we know a CD's basic composition—there's a plastic polycarbonate layer, a metal reflective layer with all the data in it, and then the coating on top—but it's impossible to tell just from looking at a disc how it will age.
"We're trying to predict, in terms of collections, which of the types of CDs are the discs most at risk," France said. "The problem is, different manufacturers have different formulations so it's quite complex in trying to figure out what exactly is happening because they've changed the formulation along the way and it's proprietary information."
Even CDs made by the same company in the same year and wrapped in identical packaging might have totally different lifespans. That's what Library of Congress researchers found when they tested twin copies of Paul Winter's Grammy-nominated 1987 album Earthbeat.
The two seemingly identical discs were exposed to extreme heat and humidity in an accelerated-aging machine. They cooked for about 500 hours at 175 degrees and in relative humidity of 70 percent—about what you'd expect on a sweltering July day in New York City, but not quite as humid as a rain forest. One of the CDs emerged relatively unscathed. The other was zapped of its musical data, completely destroyed by oxidation. You can see the ruined CD, which became almost totally transparent, on the right:
"They started out looking exactly the same," France said. "I wish we could definitively say, you know, 'If you have a CD that was manufactured in 1984, that's terrible.' But it's not quite that simple."
If you're willing to part with your old CDs, the library will happily destroy them for you. ("In the name of science!" France says. "And just so people know that no library materials are harmed." Email here for more information.) The Center for the Library's Analytical Science Samples is a laboratory for destruction, a place where researchers can practice "destructive testing" on non-library materials as a way to learn how best to care for actual library collections. Staffers at the center might opt for more destructive aging tests, like the treatment that Earthbeatsuffered, or just let discs age naturally and check in on them every decade or so.
There are all kinds of forces that accelerate CD aging in real time. Eventually, many discs show signs of edge rot, which happens as oxygen seeps through a disc's layers. Some CDs begin a deterioration process called bronzing, which is corrosion that worsens with exposure to various pollutants. The lasers in devices used to burn or even play a CD can also affect its longevity.
Then there's the wear and tear that's more in line with what you'd probably expect to happen over time—like scratches and exposure to extreme temperatures. ("If you want to really kill your discs, just leave them in your car over the summer. That's a really great way to destroy them," France says.)
But it turns out that plenty of people don't know how to care for CDs properly in the first place. For instance, the best way to hold a CD is to pinch the hole in the middle, and the top surface of the CD—the side that faces up when it's playing—is more delicate than the bottom. Again, France: "People are generally more concerned about the scratches on the bottom, but actually you can get quite a lot more damage when you get scratches on the top layer because it goes through and impacts the metal reflective layer. So quite often you find people are really careful not to put their hands underneath, but holding it in the middle is better."
It's also better not to muck up the top of your CDs with labels—the adhesive creates chemical reactions that quickly eat up data—or even permanent markers. "The moment you start to write on that top layer, you're setting yourself up for degradation," France said. So you can see why this relic—its playlist and subsequent volumes long since a mystery—has stopped working:
Recordable CDs—the kind you can burn or rewrite—tend to have more complicated degradation issues than their professionally-recorded counterparts. That's partly because they're made from organic dyes that break down faster, France told me. And as far as different kinds of discs go, CDs tend to be more stable than DVDs, mostly just because DVDs hold more data, so there's more to lose.
But this kind of obsolescence has a way of creeping up on you. Even the researchers involved with CD preservation efforts at the Library of Congress say that academics started thinking about this kind of work later than they should have. "We really haven't focused as much on 20th-century media because you just think there are multiple copies of things. People just assumed it's more widely distributed."
And the disappearance of CD players is just as significant as the failure of CDs. "Quite often, [preservation] is being cast as a separation of physical and digital, whereas in fact the whole concept is the same. Even digital is still played on a physical medium."
Disc drives are disappearing from newer models of laptops and cars. Many of the places we used to buy CDs—Tower Records, Sam Goody, Borders—are gone. The memory of jogging with a Discman in hand seems absurd now, but that rain-slicker-yellow Sony Sports model was once top of the line. Even the iPod that replaced it feels like a brick compared with its slim successors.
Yes, the ubiquity of a once dominant media is again receding. Like most of the technology we leave behind, CDs are are being forgotten slowly. Eventually, even the fragments disappear. No more metallic shards of broken discs glinting from the gutter. No more old strands of tape cassette tangled in tree branches like tinsel. We stop using old formats little by little. They stop working. We stop replacing them. And, before long, they're gone.