Is this what optical media data-rot looks like?

Question

First, the CD in question is not data related or “mission critical.” I simply scored a music CD at a thrift shop that was made in 1988; aka: 28 years ago as of this post.

We all know optical media eventually “rots” and I have had burned CD-Rs and DVD-Rs daily on me, but visually I never could see any indicator with my bare eyes that would clearly show “There! That’s the rot!”

But in the case of this Jimmy Webb CD, I have never seen a CD that seems essentially translucent due to age? Look at the pic below. Holding the CD up to any light and you can see right through it.

I tried to play it on my computer via a Samsung combo Blu-Ray/CD/DVD reader and despite the track list being picked up the CD player, it wouldn’t play. But if I put it in a standalone Sony CD player it plays, but clearly plays badly with skips and empty spaces every few seconds.

So is this what age-caused data rot looks like on burned media from the 1980s?

Answer 1

That certainly looks like disc rot to me.

Closer inspection shows that there are tiny dots in a few places (e.g. to the right of the big "K" in the image, just above the double lines) indicating failure of the reflective layer. It's this reflective layer that contains the actual data, encoded as a series of microscopic pits. The edge of the disc is also in very bad shape.

Most optical discs use aluminum for the reflective layer. Although it is protected, on CDs (but not DVDs), the layer is exposed at the edge of the disc, and deterioration is clearly visible on the disc edge. Exposure to certain chemicals in the air can cause this kind of failure to occur; hence, optical discs are best stored in a controlled environment free of harsh chemicals in the air.

Although very expensive, most archival-grade discs use 24K fine gold for the reflective layer (as well as advanced dyes and scratch-resistant layers) because gold is chemically inert and therefore not subject to this kind of degradation.

More information is available in this Wikipedia article.