How do I tell if a CD disc was burned 3 days ago or 3 months ago by physical inspection?

Question

Is there a way to tell when a disk has been burned by inspecting the disc for its physical features?

Answer 1

You can't do it reliably.

If you have a series of reference disks of the same manufacturer burned at intervals you might be able to do a rough guess based on the color of the burned layer. Generally as the burned part ages it slightly changes color so you can compare it with disks of a known age.
But:
The color-change is highly variable and is also highly dependent on how the disk was stored (dark or under varying intensity of light, temperature, moisture).
Also: The color-change takes mostly place during the first days/weeks after burning. After that it hardly changes anymore.
When you also add in that production processes and chemical make-up of the burning layer have some manufacturing tolerances it becomes even more difficult.
And 2 boxes of apparently identical disks from the same brand may actually come from different production lines or even be made by different sub-contractors.

To many variables...

The only way to be sure is to label the disk after burning with the date.
And, obviously, in case of data-disks you can read them to see the timestamps on the files.