This is the most common type of scratch and is repairable 99% of the time as this is the thickest part of disc and can take the most misuse and abuse.
 

This is the worst place for a scratch due to the data and reflective foil layers being located in the top 1% of the CD, very close to the surface and most susceptible to permanent damage. However there may be light scratches on the top of some discs and these may not affect play at all, as in the case of DVD’s due to their construction specifications. A quick way check if a CD is affected by foil damage is to hold the disc up to a fluorescent light and if you can see light shining through it then the data at that position on the disc has been permanently removed and cannot be repaired.
 

Knife-Edging usually occurs from attempted disc repairs with alternative abrasive paper based repair processes. These processes often apply more pressure to the edge of the disc resulting in the edge of the disc tapering off. This leaves an uneven surface around the edge of the disc and will often cause read problems because the laser beam, used to read the data, is being bounced off in a different direction.
The DGM-6 repair process applies an even pressure across the entire surface of the disc, preventing any knife-edging of the disc. We are quite happy to attempt to repair knife-edged discs given to us by our clients, however because the surface is no longer flat, we cannot guarantee results on knife-edged discs.

Occasionally discs may have suffered stresses that have caused damage to the internal structure of the disc. The most common being heat from paper abrasive repair processes which create high temperatures within the disc from friction, X-box games are especially prone to this. Internal damage can also occur when a disc is bent or twisted.
The DGM-6 repair process offers protection from heat by using polishing pads in conjunction with a specially formulated liquid polish that draws the heat away from the disc during the repair process. Internal damage cannot be identified from a visual inspection and although the DGM-6 process will bring the surface back to new, the internal data will still be corrupt if internal damage has occurred.