Rumors state that silver CD-R discs can damage the lasers in drives. Do blue CD-R discs with silver metallization have the same quality as gold?
• I am told by some suppliers that all CD-R discs are the same. Others tell me that gold discs are the best, another states that blue discs are of the highest quality, and some say that silver is unacceptable. What discs are best? • How are Grade A, Grade B, and Grade C CD-R discs defined? Are they all usable? • What are “audio” rated CD-R discs? Are they of higher quality? • The manufacturer of my 48X CD-R writer states that media used in the writer must be 48X certified. Is this just an attempt to control my choices of media? • I always buy high capacity, 74 minute CD-R discs. Why would anyone use discs with only 63 minute capacities? • Where can I find the new 90 minute CD-R discs? Why were they previously unavailable? • Tests of blank floppy disks can assure quality. Why not do the same for blank CD-R discs? • Why does my recording software indicate different capacities for CD-R discs from various manufacturers? • Why do I hear so much about CD-R problems? Isn’t CD-R the same as CD
Rumors of laser damage from silver discs may be from the same sources that report that Elvis is still alive. Any CD reflects only a fraction of the incident laser power, and most of that is directed to the photodetector. The amount of reflected light that returns to the laser is very small compared to the intensity that it initially generated. Neither silver, gold, nor aluminum metal layers can harm the lasers in drives. But each metal is different. Aluminum is used as the metal reflective layer in CD-ROM discs because of its ease of application and low cost. Dyes used as CD-R recording layers are very corrosive, and rapidly destroy aluminum. Gold is an inert noble metal that is not corroded by organic dyes, and therefore was used exclusively in CD-R discs for many years. Because gold is expensive, even very thin gold layers become costly as CD-R prices rapidly decline. Reflectivity of a thick gold layer is about 94% in the infrared part of the optical spectrum. Attenuation in the dye
