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Hopefully the people at IPI (Image Permanence Institute) at The 
Rochester Institute of Technology are following this thread. I believe 
they have done some longevity laboratory testing on this very same 
topic. I've written them on this thread just in case.

 From what I know, optical disks with a gold reflective layer are 
somewhat of a misnomer. A gold reflective layer only helps to keep the 
reflective layer from oxidizing if there is separation of the disk 
layers that lets air get to this layer and oxidize it (some call this 
disk rot). What's more important is the chemical composition used for 
the photo-sensitive dye layer and to what level of permanence will this 
layer have.

I've also come across quite a few disks, both DVD and CD writable, where 
contamination of oils/other substances have leached through the 
protective underside layer and rendered the disk unplayable either in 
part or in total. So one might have the best disks you can buy and 
mishandling the disk unknowingly, may effect the life of the data on the 
disk.

I believe this is the report I saw years ago on this topic. An 
interesting read: 
http://www.stilcasing.com/pdf/CDandDVDCareandHandlingGuide.pdf

Kind Regards,

John Schroth

MTS


On 5/14/2018 1:34 PM, Eli Bildirici wrote:
> I'm very far from an expert but I was under the impression that it's difficult to generalize. There are 'known good' stocks that last longer than avg - beyond the sort billed as medical grade, archival, gold, etc - and the converse. And of course this has been a moving target over the years because dye compositions change, companies go out of business or get acquired (most recently JVC-Taiyo Yuden) or give up on the market, etc. There are some known awful makes (e.g. Princo or Moser Baer) that you might expect would last for less than usual but I've got some that will still read and aren't warped or anything. Generally I remember hearing that azo dyes are worse than cyanine but I do not have a study handy to back this up. How they are kept is probably also relevant.
>
> I have found that a good resource for these kinds of questions are the media (https://club.myce.com/c/blank-media) and burner (https://club.myce.com/c/cd-dvd-and-blu-ray-writers) subforums at myce.com (formerly known as CDfreaks). There are still maybe ten people there actively doing testing (using proprietary tools like CD-DVD Speed/Opti Drive Control and a battery of drives that are compatible with those programs) of new and NOS stock and a few that have been around since the early days there. That is not a study, plural of anecdote is not data, etc. But if anybody knows of those studies, they would, and their cumulative experience should still count.
>
> May 14 2018 1:08 PM, "Steven Smolian"  wrote:
>   At the just concluded ARSC conference, one of the presenters said that the
> expected life of a CDR was 5 years. Perhaps it was Maya.
>
> At any rate, is there a study underlying this comment?
>
> Am I correct in assuming this does not apply to medical-grade gold CDs?
>
> Steve Smolian
> Eli Bildirici
> (347) 837-8337
>
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