Great info - thanks! I will mention this on my show, as I know it's something I've struggled with many times. My personal preference has always been a good sharpie, especially now that they have the clickers, but I'll definitely give the staedtlers a try next time i'm buying!

Staedtler works best for us here in the Army.I've used them for 2 years now and i swear by them...

I really enjoy roxio cd.

Who cares if the lacquer coating on top gets damaged? The data is on the bottom, not the top. It it makes a difference you should explain why.

What do I do now – 50 CDs labeled with ordinary Sharpie? Punt?

Actually, the data on CDs is not on the bottom, it is just below the lacquer surface on the top. The data is contained in the metal layer, which can deteriorate when exposed to air or moisture. The bottom of the disc has a transparent polycarbonate layer that is pretty tough. Scratches on that side can cause readability problems, but don't often go all the way through to the metal. Which is why polishing these scratches out can restore readability.

On a DVD, the metal is in the center, between TWO polycarbonate layers, so it is somewhat different, as I mentioned. But the Council on Library and Information Resources article mentioned above still recommends using CD-safe markers on DVDs just to be on the safe side. (It's not very practical anyway to keep around two sets of markers, one less safe for DVDs.)

Regarding Bob's question on the 50 CDs he's already labeled with regular Sharpies, he's probably fine. I checked the manufacturer data sheet on standard Sharpies and they are alcohol-based (n-propanolol), which shouldn't cause any problems. However, if it were me, I'd reburn anything that I expect to keep on a shelf for 10 years, and also use special archival quality media, which can be just as important for longevity. We'll cover media in a future blog article.

Is the damage cause by using a permanent marker immediate or does it continue to get worse over time? It would seem that once the solvent has evaporated and only the pigment remains, the potential for damage would be past. Under that assumption, those CDs previously labeled with a marker are already damaged (if they are going to be)or if not damaged, considered stable.

As for odor markers, the retractable Sharpies seem to create a much stronger, solvent type odor that takes longer to dissipate than standard Sharpies.

No, actually, the damage would just start at that point. Most damage over time to CDs occurs from infiltration of air and moisture, reacting with and corroding the metal layer. You can see this on affected CDs as sort of "blooms" in the dye/metal layer.

I checked the manufacturer composition for retractable Sharpies vs. regular Sharpies and the active ingredients are the same (all alcohol-based):
n-propanolol
n-butanol
diacetone alcohol.

For the CD-safe Sharpies, by contrast, the dyes are:
Ethanol
1-methoxy-2-propanolol

The Council on Library and Information Resources says this in the link I mentioned in the post:

"Contact of the disc with strong organic solvents must be avoided. Harsher solvents such as acetone or benzene will dissolve the polycarbonate and thereby damage the disc beyond repair. Limited contact (cleaning) with mild solvents such as isopropyl alcohol or methanol is permitted, as these solvents evaporate quickly and will not dissolve the polycarbonate. They may, however, dissolve or damage labels or optional coatings on the label side of the disc."

They also say:

"Scratches on the label side of CDs can be a more serious problem. Because the reflective metal layer and data layer are so close to the surface of the label side of the disc, they can be damaged very easily. A slight indentation, or pinhole in the metal from a scratch, pen, pencil, ultrafine marker, or other sharp object will destroy the reflectivity of the metal in that area on the other side (laser reading side) and the readability of the data by the laser. This type of damage cannot be repaired."

and finally:

"Numerous CD vendors have noted that the thin protective lacquer coating can deteriorate from contact with certain solvents in markers. To eliminate the risk, water-based markers are recommended for CD labeling. As a solvent, alcohol is generally less damaging than xylene and toluene, which are common in aromatic solvent-based markers. According to anecdotal reports, alcohol-based markers can be used to label CDs without causing performance problems."

I highly recommend reading this report.

Very interesting information on CD markers, thanks a lot. Could you please comment on printable CDs, that can be printed with an ink jet printer? Any danger here to the CD surface and loss of data?

I personally prefer printable white CDs, which have a protective layer of white ink between your printing and the disc. Since inkjet printers SPRAY ink, with no impact on the disc other than the ink droplets, they should be safe.

I use Edding series.
8400 for CD-R/DVD-R and 8500 for rewritables only.
Wasterbased ink, does not affect in any way the dye.

Cheers!