Disc quality is key to CD-Rs


CD burners have made it possible to combine the best of Bach and Destiny's Child on the same compact disc - prompting grand scale consumption of CD-recorder drives by computer owners new and old.

But using a CD burner at home can be as frustrating as sitting in traffic - you may wind up wasting a lot of time and get nowhere.

For example, you know you're in trouble when the first three CD-Rs out of a package of 50 discs are ejected from your $300 CD burner because it doesn't recognize them as being recordable. And prayer may be your only recourse when you discover that the CD-R you burned a week ago with five years of tax records can't be read by your computer, or anyone else's.

In either case, you may have fallen victim to poorly manufactured discs. While the odds of getting a bad CD are relatively small, industry experts agree that quality varies widely, and sadly, there are few tell-tale warnings of impending doom.

"Out of 100 discs, there may be as much as a 30 percent failure rate on some brands," says Chris Bailey, digital and optical products manager for disc and drive-maker TDK. "Some brands are pure marketers. With the smaller manufacturers, the quality may not be there, but they're selling cheaply."

If you do get a bad disc, you'll get little in the way of explanation from your computer. "The media just won't work at all - it won't be recognized, or you'll get to the end of the disc, have burned most of the information, and the disc will just kick out," Bailey explained. "It's a defective disc, and you wasted all of your time."

According to industry insiders, manufacturers rarely throw away blank CD-Rs that don't meet the highest quality standards. They often end up on a retailer's shelf or in the bargain bins at computer shows, where they sell for as little as 40 cents each in bulk.

"One day, you might buy brand X and it's pretty good. Then you buy something made by a different manufacturer and it's just awful," says Mike Johnson, general manager of Iomega Optical Business.

The good news is that you can avoid most headaches by careful shopping. The first rule, according to CD engineers, is to buy the discs that the drive manufacturer recommends. Check the instruction manual or the maker's Web site.

"If your drive manufacturer makes a disc," Johnson says, "you should buy that. Those discs have been tested by that manufacturer with that drive."

Second, look for a statement of accountability on the package. It can be a "lifetime" warranty, a technical support number or even a notice that the CD-Rs inside conform to so-called "Orange Book" specifications, originally developed by Sony and Phillips to provide industrywide standards.

Third, test the discs with your CD burner before you record anything that's critical to your existence - whether it's music or financial records. Then test the discs in your car's CD-player or your computer to see if they work.

Some recorders don't work well with some discs. "They're just bad combinations for a number of reasons," said Andreas Bohren, a physicist who works at Vivastar, a Swiss CD-R maker that has recently begun to offer discs in America.

A CD-R drive may not have enough laser power to burn the information deeply enough into a particular CD so that the disc can be used in every CD player.

"It's not so much just the media as the media and the writer," said Rich D'Ambrise, manager for engineering and new product development at CD-R maker Maxell.

To understand how CDs could be bad, it helps to understand a little about how they work. A CD-R consists of several layers - a clear polycarbonate substrate (the plastic disc itself), a microscopic layer of organic dye, a reflective metal coating - gold or silver - and a protective layer of some sort, usually a lacquer.

Blank CD-Rs can be written to only once. Newer, rewritable CDs (called CD-RWs) use different dyes made with inorganic materials so that the dye layer can be reformed as information is erased and rewritten.

When you record a CD, your drive shoots a laser beam through the clear substrate and into the dye layer, where it records digital ones and zeros in a pattern of tiny depressions, known as "pits," and unmarked areas called "lands." A CD player or CD-ROM drive reads the disc by bouncing a laser off the dye and reflective layers and analyzing the reflective pattern made by the pits and lands.

CD-Rs also differ from pre-recorded audio discs and mass-produced software CDs in one important aspect - the commercial CDs are "stamped" in bulk by precision machinery, while your CD-RW drive creates them one pit and land at a time.

Contrary to popular superstition, the color of the CD is not a sign of quality - it's created by the type of dye used and the color of the reflective backing. What's more important is the quality of manufacturing.

"You can take the best dye in the world and pour it on poorly," said Tom Wilke, director of research and development for optical business at Iomega, which makes CD-recorders and partners with Verbatim to create discs. On bad CDs, the dye coat may not be a consistent thickness, causing a variety of problems.

The type of dye can make a difference, however. Phthalocyanine dye is less sensitive to light and is expected to last 100 years, while cyanine dyes are more sensitive to light and are rated for only 50 years. On the other hand, cyanine dyes create CDs that are compatible with a wider variety of drives.

Speed is another issue. The speed of CD-R drives is measured in multiples of the speed of the original CD recorder, known in the trade as the "X" factor. An 8X CD-R drive is theoretically eight times as fast as the original.

Blank discs should be labeled with the maximum speed at which they can be written - so buying CDs without a speed rating is taking a gamble.

Joe Stinziano, director of marketing for consumer media at Sony, said higher speed CD-Rs are made to more stringent specifications - basically because the CD-R spins so quickly that laser needs to do its job faster.

While you don't have to match the disc to the drive, it's a good idea. If you can't match them, then buy a disc with a higher speed rating.

Be aware that really high-speed discs (16X or higher) may have higher failure rates.

Kieran Lynch, senior product engineering manager at TDK, said most CD drive manufacturers make sure that their drives work with discs by reading code on the disc to determine how best to burn a disc. "There really are some safeguards in there," he said.

If you use older media - for example, your drive has a maximum 12X speed and your CDs are rated 8X - record at the lower speed.

Technical experts at several manufacturers also warned against using high-capacity CDs. Discs made according to the original CD specification can hold 650 MB of data, while newer discs can hold 700 MB. That's the difference between 74 and 80 minutes of music. Unless you need the extra capacity - for example, backing up Sony PlayStation games - it's best to stay away from the larger discs.

Another area of confusion involves CD-Rs marked for "audio" use. These contain coding, and you'll need one to record music in a standalone CD writer (a stereo component). That's because the music industry gets a few cents for each audio CD-R sold as a royalty for copying its songs.

But technically, you don't need an audio CD to record your music or data on your computer's burner (any blank CD will do), and engineers say the audio CD's quality is no better or worse than standard discs.

Finally, not every CD burning problem can be blamed on the disc itself. "Sometimes the media gets the bad rap for what are drive and software issues," says Mike McCorkle, national technical support manager for Fujifilm Computer Products Division.

For example, when your computer displays a "buffer underrun" error message, you've just been told that data being transferred from your hard drive to the on-board memory of your CD burner wasn't moving fast enough to keep up with the CD writing process. Bad discs can't cause buffer underruns, McCorkle said.

"People often assume it must be the CD-R, since most drive and software problems are intermittent," he added. "Then they start scrutinizing everything from the color of the discs to the color of their shoes when most often the problem lies in other areas."

Care for CD-Rs

Recordable CDs may be made of tough plastic, but they do require some care:

Keep CD-Rs in jewel cases. Do not place them down flat on any surface. And never stack them without placing them in cases.

Store CD-Rs out of sunlight and heat. Some dyes are more sensitive to light than others. And your dashboard or a car seat can become hot enough to warp the disks.

Never write on a disk with anything that can scratch the surface of the CD-R, including hard-tipped pens and pencils. Scratches on the surface of the CD-R may poke through the thin reflective layer and destroy information you've recorded. A soft-tipped permanent marker is safe.

Make sure a CD-R is clean of fingerprints, dust and scratches before placing it in your drive. Use a lint-free cloth to wipe the CD from the center to the outside. Never wipe a CD-R in a circular fashion; it may grind in the contaminants.

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