This page is about a problem which I consider to be one of the more serious ones currently facing the PC community as a whole: The lack of reliability and longevity in writable CDs, or CD-Rs.
When CD-Rs first became widely available in the late 1990s, they transformed how people store and share data. CD-Rs made it easy to write a full CD of information quickly and easily. CD-Rs were and are used for two main reasons. The first is to exchange data between different computers, by providing a fairly large (several hundred megabyte) data medium which is portable and affordable. The other main use of CD-Rs is to archive important data for permanent, long-term storage.
There seems to be a general perception among PC users that CD-Rs are highly reliable and that they last just about forever, or at least for several decades. While this can be true, the life of a CD-R varies quite dramatically based on several factors. Perhaps the most significant factor, however, is simply the manufacturing process of the CD itself.
Unlike "real" CDs, which are physically stamped with a pattern of microscopic holes using expensive recording equipment, CD-Rs use a colored dye which changes color when exposed to certain types of electromagnetic radiation (which, in a CD writer, exists in the form of a laser beam). The changes in color of the dye constitute recorded data in a CD-R. The problem is that the dye may be prone to blurring, with the result being that over a period of time, the data on the CD-R may simply fade away, until it can no longer be read.
The longevity of a CD also depends on how the CD is treated (whether it's exposed to extremes in temperatures, exposed to direct sunlight over long periods of time, bent or warped, etc.) but even CDs which are stored properly can fade if they are manufactured cheaply. There are essentially three types of dye used in CD-Rs today:
1. Cyanine. The first CD-R technology developed, cyanine dyes are notorious for their unreliability. Pure cyanine dyes usually have a data life of less than 10 years. They have been known to become worthless in under 2 years. Typically, modern cyanine CD-Rs have other chemicals mixed with the cyanine to make it more chemically stable, but the shelf life of such CD-Rs is still questionable. Cyanine is naturally greenish-blue in color, but you cannot positively identify a dye's composition by its color, because most manufacturers today add special color dyes to conceal the true nature of their recording medium. Cyanine dye technology is patended by Taiyo Yuden.
2. Azo. Developed by Mitsubishi, patented and sold in North America by Verbatim. You'll see this technoloy touted on most, if not all, of Verbatim's CD-Rs. Azo is recognizable by its deep, dark blue (almost navy blue) color. Azo is much more chemically stable than cyanine.
3. Phthalocyanine (pronounced "tha-lo-cy-a-neen"). This is supposedly the "next-generation" CD-R medium, reputed to be "cleaner-burning" because it creates more well-defined color transitions, and said to have the longest data life of all the three dye types denoted here. Phthalocyanine CD-R technology is patented by Mitsui.
Unfortunately, because the technology and standards that make up CD technology are not well understood, much of the information available on CD-R reliability boils down to hearsay and anecdotal evidence that's almost on the level of urban legends in its quality. Here are a couple of noteworthy articles that may be of interest to those wishing more information on this subject:
http://www.cdfreaks.com/news/7751
http://www.macintouch.com/cdrfailure.html
Unfortunately, because of the desire by all the players in the market (manufacturers, retailers, and consumers) to push CD-Rs into the mass market at high quantity and low price, most of the retail CD-R market is flooded with low-quality CD-Rs with questionable reliability. The standard in CD-R buying has become to get a giant spindle of perhaps 50 CD-Rs at a cost of well under a dollar per disc, often with no brand name to speak of on the packaging anywhere. Although such CD-Rs are functional and may work for making audio CDs which you can play on the CD player in your car or whatever, you may well find that if you use these CD-Rs to store important data, some of the data may have gotten corrupted 5 years down the road.
Phthalocyanine CD-Rs are thought to be the most reliable. However, even if this were true, they are almost impossible to find at local computer retail stores in the United States, because their higher quality makes them somewhat more pricy, leading to an unwillingness by stores to carry them because of a general reluctance by consumers to buy them. Most CD-Rs sold on store shelves today will not even denote what type of dye they use; indeed, they often have no information on their recording technology whatsoever, leaving the buyer with nothing to go on except a brand name (if even that much) making CD-R recording a basically hit-or-miss proposition, quite far removed from the "indestructible" image that many consumers have of CD-Rs!
As far as I can tell as of this writing, the best advice that can be given to those hoping to preserve their data on CD-Rs boils down to a few "best practice" pointers:
Use reliable recording media. Don't go on the cheap; Absolutely avoid unbranded, mass-produced CD-Rs which come on a spindle for 25 cents a CD. That obviously doesn't mean that higher price automatically means higher quality, so exercise some common sense before you buy.
Burn at lower speeds. It's long been understood that in general, the slower the burn speed, the better an impression is made on the CD-R. If the CD is burned too quickly, the dye does not have enough time to change color sufficiently, and an unreliable burn is made. Even if both the CD media and the burning drive are rated for the burn speed, the disc may become unreliable over time. The opposite end of this is also true, however: At extremely slow burn speeds, high-speed CD-R media may actually overburn, also creating an unreadable or unreliable burn.
Store media in a cool, dry, dark place, where it will not be exposed to vibration, extremes in temperature change, or bright light.
Many people have claimed that so-and-so manufacturer produces the most reliable CD-Rs, but this is based mainly on hearsay. Many also advise you to look at the country of manufacture on the CD-R media before you buy, claiming that CD-Rs made in (for example) Taiwan are notoriously cheap and prone to data loss, while those made in more developed countries (typically Japan or the United States) are more reliable. These reports seem to bear each other out, but take them with a grain of salt, given that a majority of consumer electronic goods produced today come from Taiwan or mainland China.
Also, don't forget to consider your burner. A wide variety of companies make CD-R writer drives, and these, too, will vary in their quality and reliability.
For those who have CDs that you're having trouble reading, don't forget to thoroughly clean the surface of the CD before you give up. Radio Shack sells a nice little enclosure within which you can put a CD, spray on some cleaning fluid, then turn the disc around a few times while a rotating buffer moves across it. The cleaning device is Radio Shack Part Number 42-8257, and the cleaning fluid for use with it is RSPN 42-8259. You can also buy them both together (RSPN 42-7051), and RS also sells CD hand wipes (RSPN 42-350), which are good for use with the cleaning fluid.
If you're really interested in those phthalocyanine CD-Rs, you probably won't find them at your local computer retailer, because they're somewhat more expensive than regular CD-Rs (they range from about $1 per CD to slightly less than $2 per CD, depending on what quality you get). Here's the background on who makes them: On June 16, 2003, it was announced that Mitsui Chemicals, Inc., had "made a strategic decision to partially withdraw from the CD-R and DVD-R manufacturing arena". Mitsui Advanced Media, Inc. (MAM), the division of Mitsui that made the famed phthalocyanine CD-Rs, had been essentially bought by Italy-based Computer Support Italcard s.r.l. (CSI) after CSI acquired a majority stake in MAM. As a result, MAM as it existed changed its name to MAM-A (MAM-America), to distinguish from MAM-E (MAM-Europe), MAM's operation in France. What all this means is that if you want those CD-Rs, you can buy them from the online store at MAM-A's website. MAM-A's top-of-the-line CD-Rs are the "Gold archive" line, made using the same technology as their regular gold CD-Rs but found by their Quality Control department to be of exceptionally high quality. I don't get paid to endorse MAM-A. In fact, I'm not even trying to endorse them, but as it stands, they *do* have the industry reputation for the makers of the world's most reliable CD-Rs, so I imagine they should be of interest to those who want to make long-lasting burns. I personally ordered some of their Gold Archive CD-Rs from that website and copied some of my CDs to them. They really don't *look* any different from regular CD-Rs, so only time will tell if they're really as reliable as they claim.
If anyone out there is seriously planning to use phthalocyanine CD-Rs to archive data long-term, I would burn two copies of all your CDs, and maintain a copy in an alternative form as well (such as a conventional hard drive or a solid-state flash drive like the now-common "USB key" type of drives) so you're covering both bases.
Another brand of CD-R which apparently uses phthalocyanine is Prodisc. Notably, Prodisc's CDs are considerably cheaper than those of MAM-A; it's not clear whether this is due to quality differences or simply because MAM-A pioneered the technology and is slightly better known, and so can get away with higher prices because of brand recognition. You can buy both MAM-A and Prodisc CD-Rs online at Diversified Systems Group's website at www.dsgi.com.
If anyone out there has any more information to contribute on this subject, please let me know. I'm not looking for anecdotal evidence, of which there is already plenty on the Internet. If you have some real, hard data that can help those seeking to make reliable, long-lasting CD-R data burns, I'd be delighted to hear from you!