This week I encountered my first case of disc rot.
When new, these Imation-brand discs were a gray/silver color. As you can see now it has yellowed throughout, and has begun bronzing along the right side.
Here is a scan of the bottom side. I’ve increased the brightness so you can see the writing from the label bleeding through to the bottom, especially within the bronzed area (now seen at the left). You can also see a checkerboard pattern that suspiciously matches the pattern of the material in the CD case this was stored in, although it’s not just a pattern on the surface — it seems to penetrate all the way through.
This was from a data backup set I made circa-2002 comprising 6 CD-Rs, stored in this case:
The case and CDs were stored in a drawer in my house. No direct sunlight. Temperature controlled between 68-75 degrees Fahrenheit year-round. No humidty control, however I live in a fairly dry climate anyways.
The first disc, the rotted Imation disc shown above, is now totally unreadable. However the remaining 5 discs of the set, all Taiyo Yudens, are completely fine and readable.
Yes, storing these discs in this cheap CD case was probably not a good idea. The material has a soft fabric-y, slightly rubbery feel to it. I don’t know exactly what the material is, nor its chemical composition. I should have kept these CDs in plastic jewel cases.
That said, I have some Imation CD-Rs from circa-2001 — which were stored in jewel cases — that I had difficulty reading as early as 2017. I had chalked that up to the white adhesive labels I had printed and stuck to the tops of those CDs. Probably the glue degraded the top of the disc over time. (Incidentally these same discs are now totally unreadable today, even though they show no visible signs of decay or disc rot.)
However, I have some Memorex CD-Rs from as far back as 1999 with the same adhesive labels on them, which still read correctly today.
Bottom line, watch out for Imation CD-R’s from the early 2000’s. Of all my data & audio stored on optical media from that time, I’ve now had 3 known failures — all Imation CD-R discs. I have had zero failures so far with Taiyo Yuden, Taiyo Yuden/JVC, or Memorex.