Uneven dye coloration

What does it mean when dye rings are visible on a burned disc? Is it the result of poor manufacturing or aging (and is degradation faster?)? I’m seeing this on what’s supposedly good, albeit older media that’s been sitting on store shelves.

MID: MCC 004
Manufacturer: CMC Magnetics (PAPA)
Circa: 2004
Burn Speed: 8X

When the media is written with a Samsung SH-202J burner, one darker dye ring is visible near the hub. Scans look very good.

However, on my LG burner, I see two dye rings. Scans show a very high number of PI errors for the first 20% of the disc, followed by an excellent looking 80%.

Some burners recalibrate their laser power at specific “zones” while burning, and the visible rings are the visual markers of this power change. This may be caused by poor quality or inconsistent discs from high-quality media (and that the burner is coping with the quality of the disc), or simply due to the writing strategy of the drive itself and is completely normal.

I have run across a few discs with these rings/banding, and while most of them were good (or scanned well), there were some that went straight to the trash bin. I cannot say for sure if advanced deterioration or aging is increased since there is none evident based on personal experience.

This is quite common if a Z-CLV write strategy is used. (for example the burn starts at 4x and then switches to 8x speed)

Thanks for the replies.

Indeed, a Z-CLV write strategy seems to be the cause, although visibility of banding varies from disc to disc.

From what I read, the ugly PIE counts/patterns are consistent with less than stellar batches of Verbatim media. However, since total PIF remain low (500-1000), I can’t complain.