If you’ve tried listening to any of your old music CDs lately—if you even own them anymore—you may have noticed they often won’t play. The same is probably true of data stored on CD-ROM disks; the older ones are deteriorating and are becoming more and more difficult to use. The data CD-ROM disks are producing more read errors than they used to.
Luckily, there are easy solutions available if you take steps NOW.
CD and CD-ROM data formats were never designed for long-term data storage. Instead, they were actually developed for the ease of mass production. A CD or CD-ROM disk is composed of several layers, such as a plastic polycarbonate layer, a metal reflective layer with all the data in it, and then the coating on top.
The problem is, different manufacturers have different formulations; so, it’s quite complex to figure out what exactly is causing the deterioration of the disks. Even worse, the various manufacturers changed the formulation along the way, and production changes are considered to be proprietary information. In other words, the manufacturers won’t tell anyone what they changed and when they changed it.
Even CDs made by the same company in the same year and wrapped in identical packaging might have totally different lifespans. It’s impossible to tell just from looking at a disc how it will age.
Another issue is that mass-produced disks created in a factory use very different methods of recording the data from the methods used in the “record your own CD disks at home” variety we all use to record data onto one disk at a time. The disk you recorded at home almost certainly has a shorter life expectancy than the commercially-produced disks created in a factory.
In fact, a CD or CD-ROM disk is not a single piece of plastic. It is really a “sandwich” consisting of several layers:
Label and lacquer layers
Upper polycarbonate layer
Lower polycarbonate layer
NOTE: Rewriteable discs like DVD-R, DVD+RW and DVD-RAM lack a dye, but instead use phase-changing crystalline structure alloys at the same layer location.
The weakest part of a DVD is in the binders (or glues) that hold the polycarbonates together, forming your DVD layer sandwich.
One of the problems with long-term storage of these disks is that the layers often start to separate over time. Separation is accelerated with variations in temperature and humidity. 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. One example is leaving the disks in your car over the summer.
Hint: If you like to listen to music CDs in your automobile, the suggestion is to COPY the music CDs and then place only the copies in your automobile. Leave the original disks at home where the temperature and humidity will be kinder to the disks. Once your copies die, you can make new copies from the originals.
It’s also better to not mess up the top of your CDs with gummed labels. The adhesive creates chemical reactions that quickly eat up data. Writing on a CD or CD-ROM disk with a permanent marker, such as a Sharpie, is generally safer than using any sort of gummed label.
You can also purchase permanent markers that claim to be “safe for use on a CD.” However, the added benefits of such markers has never been proven. The standard permanent marker you purchase at the drug store or office supply store should be as good as any “special markers” for writing on the top of a CD.
Have you tried to purchase a microfilm reader recently? It is almost impossible today and probably will be completely impossible within a few more years. CD drives and CD players are disappearing from newer models of laptops, usually being replaced either with flash drives or with online storage “in the cloud.” CD players are even disappearing from automobiles, being replaced by iPods and flash drives. I suspect you won’t be able to purchase a CD drive a few years from now. Flash drives will become obsolete some day as well, to eventually be replaced with some sort of storage device that probably has not yet been invented.
Perhaps a bigger issue is file formats. For example, JPG is very popular today for saving digital images, but will that be true ten or twenty years from now? How about PDF files or music MP3 files? Will there be hardware devices twenty years from now that will read those formats?
The problem is easily solved by copying the older formats every few years to whatever format is popular at that time. For instance, if a new “XYZ format” eventually becomes more popular than PDF, software and hardware will always be available for a few years to copy from PDF to XYZ. The secret is to not miss that “window” of a few years when conversion is easily accomplished.
The more difficult problem arises when proprietary file formats are used by commercial companies in their products. If a genealogy company uses some form of proprietary format for a CD disk containing images of old handwritten records, the only practical method of converting those disks a few years later to a more modern format is to have that company make the conversion for us. However, the company may have since gone out of business (Does anyone remember Banner Blue Software?) or may have since lost interest in the project.
Ideally, we should only buy genealogy products today that use commonly-available file formats for all information storage.
If you have CDs or CD-ROMs that are sitting on the shelf, you need to copy them NOW. You can copy them to new CD disks or to flash drives or to most any other form of modern media. They still won’t last forever, but you can get quite a few more years of life from them if you take steps now to preserve the information by copying it to new storage devices. Then, a few years from now, copy them again to even more modern media that comes into common use at that time
If you (or your surviving heirs) take the time to copy CDs, CD-ROMs, DVDs, flash drives, and more digital media to modern media and file formats every few years, your valuable information can last and be useable for centuries.