A CD is a fairly simple piece of plastic, about four one-hundredths (4/100) of an inch (1.2 mm) thick. Most of a CD consists of an injection-moulded piece of clear polycarbonate plastic. During manufacturing, this plastic is impressed with microscopic bumps arranged as a single, continuous, extremely long spiral track of data.

Once the clear piece of polycarbonate is formed, a thin, reflective aluminum layer is sputtered onto the disc, covering the bumps. Then a thin acrylic layer is sprayed over the aluminum to protect it. The label is then printed onto the acrylic. A cross section of a complete CD (not to scale) looks like this:

Over a period of time the Polycarbonate Plastic (mirror side) gets scratched which then prevent the laser from reading the data information that is stored near the Aluminum layer.

Using the latest technology we polish away a few microns of the Polycarbonate plastic until the scratches are polished out. Using another process we restore the mirror surface that the disc had when new.

Please note if the scratches are too deep we will polish away what we can without getting too close to the Aluminum layer. If this is the case some marks will still be visible on the mirror side of the Disc.
In our experience most disc do play perfectly even with faint residual marks

If after repair your disc still doesn't play perfectly, we will repair the disc again free of charge, if returned to CD Hospital within 7 days. If we are unable to make your disc play again perfectly, you will be offered a full refund of the amount you paid for the repair of that disc.