Denver (CO) - Modern compact discs are remarkable storage devices, but because data on these discs are just as optical as scratches are, serious scratches can invalidate tracks or entire discs. Last month, we introduced you to the Scratch-Less disc, which claims to resist scratches through a combination of bumps, ridges, and a hard coating.

Now, Scratch-Less inventor Todd Kuchman tells us that the seemingly simple design was actually quite difficult to perfect. Kuchman spent more than four years in his garage cutting, drilling, and gluing, in order to come up with an impervious disc that also wouldn't become stuck in a CD-ROM drive.

Kuchman said he came up with the scratch resistant CD concept after seeing a girl knock over a stack of CDs to the floor. "I just knew she scratched the heck out of those CDs," says Kuchman. Thinking that there had to be a better way; he went home and started designing prototypes in his garage. His first few tries weren't very successful.

Initially, Kuchman's idea was to lift the data portion of the CD off the ground with a full ridge around the outside. Using tools like heating presses, drills and glue guns, he fashioned some discs, but discovered that they would catch and get stuck in some CD-ROM players. "This was the hardest problem for me to overcome," says Kuchman.

He experimented with partial ridges, eventually finding success with small bumps - 20, to be exact - around the rim of the disc. These bumps, in addition to a full ridge in the inner portion of the disc, solved most of the drive compatibility problem. Kuchman does admit that some CD-ROM drives still cannot read his discs, but adds that a list of those drives are on the Scratch-Less Disc Web site.

With one problem solved, Kuchman found himself in a quandary. Avoiding contact was a great way to reduce scratches, but what if someone wanted to intentionally scratch the disc, perhaps to destroy superseded data before throwing the disc away? Kuchman decided to apply hard, scratch-resistant coatings to the data side. Some of the coatings worked well, but the CD-ROM drive lasers couldn't shine through to the data. Finally, he settled on a polymer from GE Chemistry Labs.

Other disc manufacturers have been offering scratch-resistant coatings since CD-R discs were first made available. Memorex sells its own line of DuraLayer CDs, and its new corporate parent, Imation, has already made available its "ForceField" CDs. While Kuchman won't say exactly how much harder or more resistent his discs are compared to normal CDs, he does say, "They are easily a few orders of magnitude harder."

What's next for Kuchman? He tells us that future generations of his disc will have bumps and ridges on both sides. "People sometimes lay their CDs label side down and a scratch there can be just as dangerous," says Kuchman. He also plans on developing a Scratch-Less DVD-R.

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