CD-R discs are manufactured by injection-molding the 1.2 mm thick
polycarbonate substrate that contains a spiral pre-groove. The dye layer is
then spin-coated on the surface containing the pre-groove. A reflective
layer is then sputtered over the dye layer, and a thin protective layer is
spin-coated over the reflective layer.

"Color" in the polycarbonate layer relates to the visual part of the
spectrum, while the CD laser operates near 780 nm in the near-infrared.
Consequently, the visual properties of the polycarbonate are immaterial.
Modification of the infrared properties of the polycarbonate would degrade
the read/write capabilities of the disc, and is not done.

I do not pretend to be always right, but the above information is accurate,
as a bit of common-sense thought would confirm.

Media Sciences, Inc.

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of Don Cox
> Sent: Monday, August 23, 2004 1:02 PM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] ? about Burning CDs for archives
> On 23/08/04, Mike Richter wrote:
> > Arguing this technology with Jerry is about as wise as disputing
> > mathematical physics with Stephen Hawking - except that Jerry *can*
> > communicate when one is not excessively simple.
> Well, Hawking recently admitted to being wrong about one of his major
> theories, after about thirty years.
> I have seen no scientific evidence or tests here, only a blanket
> out-of-hand dismissal of the possibility that there could be any
> advantage. I don't know if there is an advantage, but the extra
> manufacturing cost is small; so if there is an advantage, then black
> polycarbonate would be worth while.
> People who are very certain about something are often wrong.
> Regards
> --
> Don Cox
> [log in to unmask]