Re: [ARSCLIST] Replating CDs

[Don Cox <doncox@xxxxxxxxxxxxxx>]

On 06/03/08, Ernie Longmire wrote:
> Don Cox wrote:
>> On 03/03/08, Steven Smolian wrote:
>>> As a lad, I operated a large vacuum metalizer, making shiny silvery
>>> iciles for a business. - thats over 50 years of technology ago.
>>> Nonetheless, I doubt replating a CD could be done effectively.
>> 
>> Why not? The metal is evaporated onto the surface in a vacuum, just
>> like
>> you were doing.
> 
> Freshly-molded CDs get their reflective layer under clean-room
> conditions and the material is applied to a virgin surface. To
> properly re-coat an existing CD you'd need to remove the original
> label ink, lacquer and reflective coating, then prep the surface in a
> way that allowed the new coating to adhere properly, 

AFAIK there is no "prep" of the polycarbonate before the metal is
evaporated onto it. It has only to be clean.

> all without
> damaging the existing pits that the old coating was adhering to
> (assuming they weren't already damaged by the circumstances that made
> the disc need a re-coat in the first place).
> 
Of course. All that goes without saying.

> It could probably be done, but if I had a disc that was worth the
> effort, I'd want to try the IRENE approach first: find a way to
> directly image the pits from the "clear" side of the disc and
> reconstruct the encoded data from that. 

That is what any CD player does. We are talking about valuable discs
that cannot be read in the normal way, because the reflecting layer is
damaged.

> Even if that side is so badly
> damaged it requires resurfacing before you can do any imaging, that
> process still poses less risk to the actual data than trying to chisel
> any remaining metal out of the pits themselves.

I said nothing about chiseling. The process would use a chemical solvent
and possibly ultrasonics.

Regards
-- 
Don Cox
doncox@xxxxxxxxxxxxxx