For years, CDR media used a dye layer that would make it obvious that one side was darker than the other ( a future TechTip will deal with dyes ). All you needed to figure out was which was which. Now, "there's a new kid on the block." A couple of major disc manufacturers have figured out a real neat trick with CDR. If they add a certain color dye to the standard phthalo-cynanine dye found in many of the better CDR, it tricks your eye into thinking that neither dye is present. The tell-tale yellowish green dye color disappears leaving the disc looking more like a replicated disc than a recordable CDR. A true silver / silver CDR.
OK, now how do you tell which is the label side (up) and which is the record side (down)? Here's the trick! It's called the stacking ring and its normally about 1/2 of an inch from the absolute center of a CD. The stacking ring is a ridge that protrudes from the CD on the bottom or the record side of the disc. Normally, there is a matching groove on the top or label side of the CD (but not always). By feeling for the stacking ring you should always be able to tell "which side is up!"
by Al Foster, VP
dataDisc, Inc.