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The organic dye used in the Mitsui "Gold" discs is Phthalocyanine, which is actually blue in color. Conventional CD-Rs use cyanine, which is green and some use azo. There's a good explanation of all of this on the MAM-A web site:

http://www.mam-a.com/technology

Although I used their gold CD-Rs for archiving, I don't expect to be around to verify whether or not they last the claimed 300 years. And, John's point about having hardware to play these discs decades down the road is a good one. 
 
Gary

____________________________

-----Original Message-----
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of John Schroth
Sent: Monday, December 12, 2016 1:34 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] CD Labels - was Sticky CD sleeves

I think I remember seeing a report from the Image Permanence Institute, about CD R and DVD R disks. Of the four different common chemical compounds used to formulate the dye data) layer, only one type had any real permanence.

Gold disks have gold just in the reflective layer, which is not supposed to oxidize if the layers are separated (disk rot). You could have gold reflective layer disks that have a poor chemical formulation for the photo sensitive dye layer and the data will still decay with a gold disk just as fast.

If content is going to be on disk only (not recommended for many reasons), at least two different copies on at least two different reliable manufacturers stored in at least two different physical locations. Also have a succession plan to move the data to new disks every 5-6 years if CD, 8 years if DVD.

If you're relying on claims that tout gold disks lasting 100 years, even if the data does last, good luck finding a player/drive for them!

Just my two cents...

John Schroth

MTS


On 12/12/2016 12:06 PM, Gary A. Galo wrote:
> One thing I have consistently observed is that, initially, the Mitsui/MAMA gold CD-Rs have much higher error rates than good conventional discs like the Taiyo Yudens, using Nero DiscSpeed's disc quality scan. All of the errors are correctable, however. The question of course, is how stable each will be for the long haul.
>
> Gary
>
> ____________________________
>
> Gary Galo
> Audio Engineer Emeritus
> The Crane School of Music
> SUNY at Potsdam, NY 13676
>
> "Great art presupposes the alert mind of the educated listener."
> Arnold Schoenberg
>
> "A true artist doesn't want to be admired, he wants to be believed."
> Igor Markevitch
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List 
> [mailto:[log in to unmask]] On Behalf Of Lou Judson
> Sent: Monday, December 12, 2016 11:33 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] CD Labels - was Sticky CD sleeves
>
> Has it been proven this far down the road that gold CDRs really last longer than normal ones? Seems to me it is still a chemical process and they would be un-permanent, even if they do last somewhat longer... Is the jury still out?
> Lou Judson
> Intuitive Audio
> 415-883-2689
>
> On Dec 11, 2016, at 11:56 PM, Aaron Coe <[log in to unmask]> wrote:
>
>> Yeah, I don't even offer optical media as preservation medium option anymore.  I used to provide my clients with MAM-A 24 Kt. Gold Archive CD-Rs & DVD-Rs, labeled using a Rimage Prism Plus thermal printer.  The printer cost a pretty penny back in the day, but it printed labels that wouldn't smear if they got wet or were rubbed.  Very professional looking.
>>
>> -Aaron
>
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