Frequently Asked Questions About Compact Discs

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CD discs that arrive in cardboard sleeves seem to work o.k. Why do a few suppliers continue to use expensive jewel cases?

Discs that "work o.k." may actually be defective. Although sophisticated circuitry in many players can overcome serious quality problems, a small amount of additional damage can result in an unreadable disc. Or discs that "work o.k." in one drive may not be readable in a different system. Significant differences in drive error correction and servo capabilities have appeared as speeds have increased, therefore functionality in one drive does not predict successful interchange in all drives.

CD manufacturers carefully control their processes to produce high quality discs. Unfortunately, quality subsequently degrades during storage, handling, and shipping. The famous (or infamous) jewel case has an excellent reputation for minimizing quality degradation. This case securely holds the disc such that neither the important readout surface nor the sensitive label side touch the polystyrene case. Another advantage of jewel cases is protection of the rim of the disc. Minor rim damage can generate unbalance, resulting in serious problems in high speed drives. Volume usage of jewel cases have significantly reduced costs, and they are no longer expensive. Many software suites arrive with a jewel cased CD-ROM nestled among the manuals and other documents.

One complaint about jewel cases focuses on the difficulty of removing the disc. In fact, a favorite cartoon suggests that if we really wanted to stop kids from smoking tobacco, we would ask the inventor of the jewel case to design cigarette packs. In practice, a major shortcoming of the jewel case is the tendancy of the brittle case to crack when shipped in the mails. Although this problem can readily be solved by the use of a padded envelope, alternative mailers have appeared in the market. Another disadvantage of jewel cases is the expense of inserting eye-catching printed matter that can readily be printed onto other types of packaging.

Board stock envelopes have become popular, and will survive the postal system. However, two new problems are created. First, the envelope survives the postal system, but what about the disc? Forces generated by postal cancelling and sorting machinery are directly transmitted to the CD disc and can seriously degrade performance. Second, board debris, dust and grit can damage the disc that is in contact with the interior surface of the envelope. The second problem can be addressed by the use of a soft, non-woven liner similar to those used inside diskette cases. This liner not only protects the disc from contamination but can also provide some cleaning action when the disc is inserted or removed. The liner does not solve the first problem, since it provides minimal cushioning. In addition, cardboard always generates debris, and it is better to remove the source of contamination than to merely insert an intermediate buffer.

Flexible plastic wallets containing a non-woven liner may not contaminate discs, and can even clean the disc, but require additional protection, such as a padded envelope, to ensure that mailed discs will not be damaged. They are a viable alternative to jewel cases in boxed software, but still have the disadvantage that both surfaces of the disc are in contact with the wallet. Tyvek or paper window sleeves also offer minimal protection. Plastic trays are another popular type of CD package. Sufficiently flexible to survive the postal system, they protect both the readout surface as well as the outside edge. Disadvantages are poor protection of the delicate label surface, and direct contact between the readout surface of the disc and the bottom of the tray. Any contamination in the bottom of the tray can damage the disc as the package is bounced around.

The jewel case remains the package of choice, suspending both surfaces and the rim within the box, and preventing their contact with surfaces contaminated by debris or grit that can damage the disc during vibration or shaking. Some manufacturers have added high impact polystyrene to the crystal polystyrene used for conventional cases. The result is a more rugged case that is less likely to fracture. Some boxes are available that use polypropylene, a proven video tape packaging material. All require secondary protective packaging for mailing. Innovative suppliers will continue to offer new and useful options. Evaluate them by their ruggedness and by their ability to suspend the disc. Clean, plastic wallets lined with non-woven fiber can be an excellent alternative provided that they are surrounded by additional protection.