my understanding of cd R and RW is thus
both have a flat aluminium backing
they both contain a dye
the CD-R dye when heated over a certain temp (like 400C+)changes from
something which transmits the red light to something that blocks it.
a RW uses some funky crystaline die
when heated over around 500C it crystalises becoming noncondictive, when
heated over 650C it decrystalises becoming conductive again. Which is why
you need to erase CD-RW's before you can use them.

the actual terms used crystalise and the directions of the transformations
are most likley wrong btw but the method is basically correct.


> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Stephen R Phillips
> Sent: Wednesday, May 04, 2005 14:05
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Marx Generator 1 megavolt plus output
>
>
>
> --- Eric Jorgensen <eric_ke6us@yahoo.com> wrote:
> > A friend at work had told me about microwaving CDs
> > several months ago. The CD shown on the EHV web page
> > has very random "lightning-like" traces. Mine is a
> > burn pattern that closely resembles the illustrations
> > you see in books of the tracks and sectors on a hard
> > disk surface.
> >
> > I'm not sure why, but maybe it has to do with the fact
> > that the author's CD was pressed and mine was a CD-R
> > that I burned.
> >
> > Anyway, it is VERY dramatic when you do it. If I had
> > seen it done or even seen the results I NEVER would
> > have tried it on my microwave (the EHV author
> > recommends you use someone elses). My friend just
> > said, "Try it. It's interesting." My microwave was
> > unharmed, but I really don't know how it could have
> > survived.
> >
> > I don't have a website to show it, but if anyone wants
> > a *.jpg of the startling results, e-mail me offlist.
> > No, I won't burn one for you.
> >
> > Eric
> > KE6US
> >
> The reason for that is the volume pressed comercial disks using an
> aluminium coating and CD-R's are a special metalic polymer dye instead.
>  CD-RW's are more likely to work that way, since they appear to have a
> shape memory material in them that deforms when heated (written) a
> certain amount. When heated to a different temperature they loose there
> shape again and are erased.
> I believe they use special writters for the high volume comercial
> production of the disks (see very high powered lasers).  After the
> disks are written they are then silk screened with whatever stuff they
> are supposed to have on them.
>
> Anyhow the aluminium blows out because of dieletric break down in the
> high power RF field generated by the magnetron in the microwave.
>
>
> Stephen R. Phillips was here
> Please be advised what was said may be absolutely wrong, and
> hereby this disclaimer follows.  I reserve the right to be wrong
> and admit it in front of the entire world.
>
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