Note that the "vintage CDs and DVDs" that "have a life of over 80 years" are pressed disks or produced on industrial burners with lasers powerful enough to make mechanical pits in the material where the data is recorded. The recordable CDs and DVDs you can "burn" at home record the information in a film that's more like a badly developed photo film (if anybody remembers those) than to the grooves and bumps in vinyl (or for CDs, in really hard plastic?).

Any material "photosensitive" enough to be changed by the low powered lasers used in computer burners can be changed in ways that degrade the data stored on them by any number of other things like heat or temperature changes, sunlight or low level uv emissions from some interior lighting, or chemicals ranging from cleaning materials to medicines, or by contaminants from gerbil dander or cockroach footprints.

In the interval while CDs offered cheaper "bit storage" than alternatives, over a period of a few months I "archived" about 360 CDs that were then stored in jewel boxes, inside drawers, in the dark, in a quiet part of the air conditioned office area. Approximately five years later, hard drive capacities with much larger sizes were economically available, so I copied the CDs back to a backup HD.

All of the CDs were "verified" when made. Approximately 10% of the CDs were completely unreadable when I pulled them out to transfer the data. Another 10% had some, but not all files recoverable. Only about 80% appeared to be fully readable after just 5 years in "benign" storage.

Because I had deliberately made the CDs so that each individual file was on three or more CDs (mixed more or less at random), my actual data loss was quite low, but loss would have been quite annoying if I hadn't had an unusually high level of redundancy in the disks.

For comparison, at the same time that I transfered all the contents from the CDs, I went through my accumulation of old 3.5" floppy disks that had been stored similarly for 10 to about 18 years, and found about 40% of those completely unreadable with almost no disks from which all files on the disk could be recovered. (But floppies were never considered particularly reliable even when they were about all we had.)

Note too that several individual files from the CDs were each larger than the total contents of a folder containing all the files from ~60 3.5" floppies. (Just in case you're making a five year plan for getting the storage space you may want in 2016.)

And anyone who thinks that "writing it in stone" is more permanent should take a walk through any 100 year old cemetery and see how many of the stones can be read as cearly as when new.

John