Exploding CDs

On Wednesday, September 23, 2020 at 3:36:23 PM UTC-7, Jeff Urban wrote:
> They simply explode for no reason apparently. Of course there is a reason but what is it ? 
> 
> I am thinking about polymers outgassing inside corroding the aluminum and making it corrode. That for most metals makes them lose mass, which has to go somewhere. 
> 
> From what I hear it is when they are handled, but not abused. They have not been sitting out in the sun for days. This comes from an audiophile forum and they don't abuse them. 
> 
> I think I will go back and ask what is the AGE of theses CDs. 
> 
> Thing is, somewhere around here we probably have someone who knows about polymers and all that. Maybe they want to chime in. 
> 
> I think it is a hell of a curiosity. 
> 
> I wonder if it can happen to the holographic disks. Imagine having all your movies and music on one disk and it goes poof. Thing is I do not believe they use aluminum. They are depth multiplexed and like wherever thy want, not like a dual layer DVD. so they pretty much can't be using aluminum as the reflective substance.

Sounds like an "Urban Myth"

On Thursday, 24 September 2020 08:36:23 UTC+10, Jeff Urban  wrote:
> They simply explode for no reason apparently. Of course there is a reason but what is it ? 
> 
> I am thinking about polymers outgassing inside corroding the aluminum and making it corrode. That for most metals makes them lose mass, which has to go somewhere. 
> 
> From what I hear it is when they are handled, but not abused. They have not been sitting out in the sun for days. This comes from an audiophile forum and they don't abuse them. 
> 
> I think I will go back and ask what is the AGE of theses CDs. 
> 
> Thing is, somewhere around here we probably have someone who knows about polymers and all that. Maybe they want to chime in. 
> 
> I think it is a hell of a curiosity. 
> 
> I wonder if it can happen to the holographic disks. Imagine having all your movies and music on one disk and it goes poof. Thing is I do not believe they use aluminum. They are depth multiplexed and like wherever thy want, not like a dual layer DVD. so they pretty much can't be using aluminum as the reflective substance.

See (for example): https://tinyurl.com/y5yf7g5n

Audio CDs vary their RPM to to get a constant-rate data stream (CLV). The limits are very mild numbers.
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Cheers,
Chris.