Durabis is the name given to a protective clear polymer coating being developed by the TDK Corporation. This coating will be used on BD-ROM discs to help protect against stains and scratches to the discs. The first BD discs were protected instead by being enclosed in plastic caddies, but it was thought this would give HD DVD an advantage as HD DVD discs can be handled like DVDs and CDs. Durabis will make it easy to clean an optical disc and apparently is so tough you could attack a disc with a screwdriver several times without damaging it.
In order to reach a capacity of 25GB per layer, BD-ROM discs use a much higher numerical aperture than DVD and the newer HD DVD. The numerical aperture of Blu-Ray Discs is 0.85, compared to 0.6 for DVD and 0.65 for HD DVD. This is exactly why a tough coating is needed. A single scratch to a BD disc could possibly destroy a very large portion of the content stored on the disc. This gets more worrying for gamers when you consider the PlayStation 3 console will use Blu-ray Disc technology for games.