Posted by JoeBloe on 12/03/06 16:03

On Sat, 02 Dec 2006 12:47:49 -0800, dgates <dgates@spamlinkline.com>
Gave us:

>I had always believed that DVD-R's and DVD+RW's had bottoms that could
>scratch pretty easily, but that commercial discs could take a little
>abuse.


The "read surface side" Is the side of the disc that the laser peers
THROUGH to see the read surface (where the pits are at). This is the
same hardness poly sandwich for all optical discs.

The poly layer where the pits are burned on a writable form disc is
VERY close to the TOP side surface of the disc, being coated merely by
some lacquer in the worst cases.

So, scratch the bottom, read surface and eventually the scratches
are so bad the even the redundancy coded into the disc can't fix the
read errors. Scratch the top, and the data is just plain gone.

Pressed audio CDs also have their data layer very close to the top
side, and are easily damaged by top side scratches.

The whole premise is that if one never touches it, it never gets
marred, smudged, or scratched, and never experiences a read error.

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