"Two-tone" discs

K Henderson henderson.120 at OSU.EDU
Fri Jan 4 21:14:34 EST 2002


Tim (the Enchanter) suggests...

>interesting...i always thought that the two-tone discs were recordable, and
>the monotone discs the ones that standard mfg.s released in order to tell
the >difference between  cds & cd-rs. (IMO-just a wild guess)

No, no...I'm talking about something entirely unintentional and non-uniform,
more like a 'discolored blob' effect that can only be the result of uneven
processing.
Two shades of silver with slightly different reflectivity...that's all.

Nothing at all to do with marking differences, or colorization of CDR's.

Grakkl (FAA)

>> A quick tech question...
>>
>> I've long wondered why some CDs have a strange two-tone hue to the playing
>> surface...you know, it looks like in the manufacturing process there's some
>> form of lacquer or something going down onto the Aluminum surface before
>> encasement in the acrylic (or whatever plastic it is).  And then for some
>> reason, the 'lacquer' doesn't coat evenly over the surface and forms an
>> irregular boundary somewhere in the middle of the disc (not to be confused
>> with the very regular boundary that is often visible which represents the
>> point at which the music 'runs out' from inside-to-outside).  I've got alot
>> of discs with this strange two-toned hue, but none of them ever have any
>> problems being played or read.  But what I wonder is what causes it, and is
>> it really some sort of defect?  If so, then why does it happen so often?
>>
>> Just curious on a cold January day...Grakkl (FAA)



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