the CD is held up to a strong light, light shines through several pin-prick-sized holes. Discoloration of the disc, which looks like a coffee stain on the disc. See also CD bronzing. In audio CDs, the rot leads to scrambled or skipped audio or even the inability to play the disc. Using surface error scanning to check the data integrity allows discovering loss of data integrity before uncorrectable errors occur. Variants Laser rot Laser rot is the appearance of video and audio artifacts during the playback of LaserDiscs, and their progressive worsening over time. It is most commonly attributed to oxidation in the aluminum layers by poor quality adhesives used to bond the disc halves together. Poor adhesives separate over time, which allows oxygen in the air to corrode the thin aluminum layer into aluminum oxide, visible as transparent patches or small dots in the disc. Corrosion is possible due to the thinness of the layer; normally aluminum does not corrode because it is coated in a thin oxide layer that forms on contact with oxygen. Single-sided video discs did not appear to suffer from laser rot while double-sided discs did. The name "laser rot" is not a misnomer; although the disc degradation does not involve the player's laser, the "rot" refers to the laser disc itself. Laser rot was indicated by the appearance of multi-colored speckles appearing in the video output of a LaserDisc during playback. The speckles increased in volume and frequency as the disc continued to degrade. Much of the early production run of MCA DiscoVision Discs had severe laser rot. Also, in the 1990s, LaserDiscs manufactured by Sony's DADC plant in Terre Haute, Indiana, were plagued by laser rot. HD-DVD rot Many HD-DVDs, especially those produced by Warner Bros. between 2006 and 2008 developed disc rot not long after production. Disc rot was also more common on double-sided HD-DVDs than on single-sided HD-DVDs. See also CD bronzing, a type of disc rot, affecting a subset of CDs and DVDs, causing a bronze-colored darkening of the playable surface and eventual loss of readability. Conservation and restoration of plastic objects Data rot, a similar concept DVD-D and Flexplay, disposable optical disc formats designed to become unplayable after a limited time M-Disc, an optical disc format claimed to have a reduced rate of rot compared to conventional DVDs References External links Mac Observer article "CD Bronzing" article, with PDO