Does anybody know of any storage technique to prevent the formation of pin holes in the metalic layer of audio CDs?

Lots of my old CDs are plagued with them. It is not a back up question. I really would like to know of some way to preserve the CDs against what appears to be oxidation.

I am talking about the original, pressed audio CD and looking for useful life longer than 20 years.

try using better CD-R media. Better yet, use DVD instead. Good luck.
edit - might want to look into your CD storage methods too. I keep mine in a case in the dark, cool closet. The good quality ones are still readable after 6 or 7 years. Now is a great time to backup to DVD.

Thanks for the suggestion. But I am really talking about the original, pressed audio CD and looking for useful life longer than 20 years.

It may actually be due to contact with paper - inlay cards and such. Try to store them in such a way that they don't come in contact with anything.

Speaking of oxidation/corrosion, what about those CDs that have stuff printed on top of the metallic layer. Are these as susceptible to oxidation just as much as those without a printed surface?

If you haven't seen it already, the CD and DVD Care and Handling Guide provides some good guidelines on how to store CDs.

Now that you mentioned I just realized that all the defective CDs I have (with the pin hole problem) had almost no printings on the top. However it could be only a coincidence. Besides it is hard to see pin holes when the CDs are darkened by the (painted) labels.

Thanks verbajim that is a great guide. I still have to finish reading the whole thing.

If by "pinhole," you are describing what I think you're describing (tiny little speckles of light that appear through the disc when it is held in front of a light source), I have had a few newer CDs that have been plagued by "pinholes." But I believe that older CD's are more susceptible to them as they do not have a painted label . . . only printing. On such discs, It is much easier for the coating on the top side to become damaged.