-=> Quoting Will Thompson to All <=-
 WT> On what side of a CD is the music -actually- on?  I've heard Label
The CD is a mixture of digital & optic technologies.
If you were to look at a disk EDGE on, with label up, here is what you
see:  (this is DEFINITLY not to scale!) :-)
______ label printing
______ laquer coating (VERY SOFT!)
^^^^^^ THIN coating of aluminum on top (next) layer of molded pits.
^^^^^^ Pit track molded into to top of polycarbonate wafer
______ bottom (polished) of thick polycarbonite wafer (very hard!)
The laser shines up (at a slight angle) and reflects off the aluminum
vapour coated TOP of the molded pit track of the polycarbonite wafer. 
The laquar is thin compared to the bottom and is VERY EASILY DAMAGED.  Even
a fingernail through the label is death to the pit track.
The reason for the thick polycarbonate wafer is that scratches that
happen on it are out of focus with the pit track.  However, if the label
is dented, that dent can easily travel through to the pit layer and
damage it directly, after which little hope of repair remains.
You can look through many cd's that have a think aluminum coating.  Just
choose a bright light source and one with little label printing. :-) 
You'll also notice the odd pinhole as well where the aluminum didn't
take.  These are usually small and don't account for severe errors.
See ya, Cameron Hall
cameron.hall@bluebeam.gryn.org | ad121@freenet.hamilton.on.ca
Blue Beam BBS | 905 662 5784 | Stoney Creek Ontario Canada | v34 vFC FAX
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