A 1980s Urban Legend Claimed CD Sound Improved By Coating The Edges With What?
Answer: Green Marker
In the late 1980s and early 1990s, a potentially harmful and entirely ineffective technique for improving the sound quality of compact discs was making the rounds in a fashion befitting any well told urban legend.
The specific claim was that carefully marking the inner and outer edges of a compact disc with a green marker would radically boost the quality of the music on the disc. By what mechanism, you might ask, did proponents of the technique claim drove the improvement? The claim was that marking the edges of the disc prevented stray laser light from escaping or entering the disc and improved the playback of the album contained therein.
The only problem with this logic, as anyone with a cursory knowledge of how digital discs are encoded would immediately see, is that the laser either reads the disc or it doesn’t. There is no need to modify the disc to absorb or reflect additional laser light. Further more, the chemicals in a permanent marking pen can potentially damage the lacquer on the compact disc, exposing the thin sheet of aluminum encased within the plastic to oxidation. Ultimately, the chances of marking the disc up have absolutely no chance of improving the quality of playback but do have the potential to ruin the disc.