An Urban Legend from the 1980s claims that the CD sound was improved by coating the edges with something.

Answer: Green Marker

In the late 1980s and early 1990s, a potentially damaging and totally ineffective technique for improving the sound quality of CDs made ends meet in a way that would match any well-known urban legend.

] The specific claim was that carefully marking the inner and outer edges of a CD with a green marker would radically improve the quality of the music on the CD. But what mechanism, one might ask, has advocates of engineering assertion made the improvement? The claim was that marking the edges of the disc prevented laser light from leaking or entering the disc, and improving the playback of the album it contained.

The only problem with this logic is that anyone who has a cursory knowledge about how digital discs are encrypted immediately sees that the laser either reads the disc or not. It is not necessary to modify the disc to absorb or reflect additional laser light.

In addition, the chemicals in a permanent marking pen can potentially damage the paint on the compact disc, exposing the plastic-encased thin aluminum foil to oxidation ̵

1; the great old Sharpie seen here is best for that Describe the label space of a burned CD, not for foaming the CD margins. Finally, tagging the disc has absolutely no chance of improving the playback quality, but has the potential to ruin the disc.

Courtesy of Sharpie.