I back up a lot of photos on CD-Rs. Recently while viewing some photos, I got some CRC errors. I looked at the underside of the CD and saw this!
I do not know what this is or what caused it, but it looked like some sort of stress pattern. It cannot be wiped off. Maybe it is due to the months of storage in a cardboard box in hot and humid weather. Plain and simply I have no idea.
Checking through all my other photo CD-Rs, there was only one other disc that looked like it was at the beginning stages of forming this pattern. Both discs were TDK Inkjet Printable CD-R80. The second disc still worked perfectly though. I have other TDK CD-Rs that look fine and work fine too.
NOTE: Even though other brands of CD-Rs have not shown this pattern, some of them still die. I have made it a point to have duplicates of everything. I am seriously considering buying several external hard disks for long term storage though.
I needed to burn some stuff onto a CD. So I opened up a new jewel cased TDK CD-R. It had the same marks as well. I proceeded to open ALL my TDK CD-Rs and ALL of them have the same marks. Either I got a bad batch or TDK makes very bad inkjet printable CD-Rs.