Cleaning With Care > Looking After Optical Disc “Before Storing” 

Prevent fingerprint, stains and smudges from being left on the disc is important as it can reduce the chance of mold, moisture that is in midair to be bonded onto the disc surface which may accelerate degradation of the disc thus reduce the usage life of the disc.     
So it is strongly advised to thoroughly clean disc before storing into casing with specific water-based cleaning fluid and wipe off with fine Microfiber.