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On 26/08/2011, Tom Fine wrote:

> The fallacy of all this age-claim stuff is that they test under known
> and/or current conditions. How can anyone project what the conditions
> will be as we get a couple of centuries out? What if a comet hits and
> toxifies the atmosphere? What if there's a nuclear or chemical
> conflagration? What man-made chemical compound is 1000 years old? 

Bronze, steel, glass, concrete (Roman), ink, paint.

> So
> how does anyone know exactly what happens with a chemical compound
> centuries from now? I think it's dumb to even try and make claims of
> hundreds of years, but OK to say "reasonable testing conditions
> (spelled out in detail so as to withstand scientific scrutiny) tell us
> that this device and its component compounds should operate to current
> specifications for XX decades" with an outside cap of 100 years or so.
> And even then, all sorts of caveats should be included about potential
> atmospheric changes, ideal storage conditions and the possibility that
> they won't be possible within this timeframe, etc. I have no belief in
> any claims of semi-permanence for any complex technology-driven device
> or compound.
> 
The question is whether there is an obvious way in which the record can
fade. Standard current DVDs and CDs use a photographic process with no
fixation stage. It is obvious that the process can continue as it would
with a developed but unfixed film.

On the other hand, a 78rpm disc can be physically broken, but there is no obvious
chemical way for the grooves to fade away.

A disc in which the information is held in a physical shape, such as
dents, bumps or varying grooves, is inherently more permanent than one
that depends on dyes.

Regards
-- 
Don Cox
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