Concentric scratches

[TomB19]

I picked up some crazy cheap DVDs at a garage sale and many of them have deep, concentric, scratches. These are the worst possible scratches, as they follow the data tracks. It's the most brutal and savage damage to a disc, short of breaking it into pieces.

I don't care about many of them, as they aren't my style, but there are a few I would like to save. These are going to take a ton of polishing with PlastX.

Any idea what causes this? Perhaps someone has a drive full of sand? Anyone else seen this?

[dcoke22]

I've seen people mention using gel-gloss to deal with scratches on discs. I've never tried it (never had to), but it seems to have a bit of wax in the formula to help fill in scratches.