3.4.3 Optical discs

Optical discs must be kept free of mechanical damage and scratches. Scratches on the read-out surface will obstruct and/or divert the laser beam, while a damaged protective layer on CDs and BDs will endanger the chemical integrity of the reflective layer. Writing on protective layers (label side) can only be done on recordable discs and then only by using special CD felt pens. Ordinary felt pens must not be used as their solvents may dissolve the protective lacquer. Writing with hard tipped pencils or ballpoint writers may mechanically disturb retrievability. Bending of optical discs must be avoided, as this may crack the reflective layer. Consequently, when releasing optical discs from the centre holding clamp, two hands should be used — one to release the holding mechanism and the other to remove the disc.