"Before that reassignment, the group did accept the test results indicating that a properly recorded and stored DVD disc ought to last 39 years with a 95% success rate while a CD-R under the same conditions (using phthalocyanine dye instead of cyanine or azo-cyanine) ought to last 112 years with a 95% success. CD-ROM and DVD-ROM media should outperform the organic dye-based equivalents. Oxidation of the polycarbonate is the limiting factor in those cases."
Thanks Joe, some interesting information. Would it also stand true that the quality of the manufacturer of DVD disks may factor into not only the lifespan of the media dye breakdown but into the thickness and quality of material that is the buffer on top of the actual dyes? In essence if the top layer is thinner or of poor quality that Sharpie/marker inks could penetrate?
Here is an interesting test I did:
What made me search for a safe removal of Sharpie ink from a DVD was that a Librarian had marked a double sided disk for identification on one side of the playing surface not realizing that there was information on both sides. This caused the disk to be unreadable in these areas on the written side.
I took an old DVD backup that I had no need of anymore and wrote on the playing side with a Sharpie. I then took a soft cotton swab dipped in Isopropyl alcohol and softly wiped out the info I wrote on the disk in marker. It came off easily and cleanly.
I then tested the DVD and there didn't appear to be any problem randomly playing it. The area where I had marked previously hung up on the video and wouldn't play but after cleaning it with alcohol the disk now worked perfectly in that area. Whether it will cause problems in the future I can't say.
Another interesting note... I used a fine point felt tip permanent Sharpie to write the test. After removing the black ink with the alcohol I could faintly see exactly what I had written on the disk surface. It seemed it either scratched or etched into the surface of the DVD.
Clarkr, very interesting test you performed. Thank you for checking that out. I had never heard of the mere presence of black ink disrupting video play on a disc. Very useful info if consistently true. I will say it again, printable discs are the safest media to use (and using a quality labeling method like a DiscPainter or other disc printer).
Joe, you stated that DVDs are generally less prone to labeling damage than CDs and I have no reason to doubt you. I do know that Fellowes' sticker labels expressly warn that their stickers should not be used on DVDs. I don't know why but just wanted to pass that on.
clarkr--
The thickness of the upper coating or its durability is a factor only for CD-Rs. The thickness must be within specification, but there are a number of very thin coatings that can cover the lacquer layer and still allow the disc to be within specification. The quality of the manufacturing is indeed a big factor in the life of a medium. If contaminants get into the mirror layer from an unclean vacuum deposition chamber, those contaminants may be able to chemically damage the dye layer over time. (This has happened already to several manufacturers in the early days of CD-R and DVD+/-R.)
The DVD you cited in your example had problems because the laser light could not penetrate the marks on the disc. The alcohol removed almost all of the ink pigment except a small amount that was absorbed by the porous polycarbonate--there was no etching unless the ink carrier was very acidic (not likely). Since the laser focuses on the middle of the DVD and not on the bottom surface, a player should now be able to read the disc.
Davis777-
DVDs are less prone to writing damage than CD-Rs. The are far more prone to damage from adhesive, paper-based labels, however. This is because the paper expands and contracts with the absorbption of moisture, and even the slightest change in radial expansion/contraction can cause tilt errors in the sandwich construction of DVDs with their narrow tracks. NEVER use paper labels on DVDs. Polyester labels designed for DVD use are far superior and do not seem to alter tilt according to the tests results I've seen. Paper labels are OK for CD-Rs only if they are aligned properly. Tilt is much less of a problem because of the solid, one-piece of plastic that forms the CD-R base and the much larger, wider tracks and marks of this format.
Thanks for the straight dope on why sticker labels should never be used on DVDs. This is not common knowledge and I know of many people who put sticker labels on their DVDs. When you need the best info ask Joe at Afterdawn.
Thanks
I think that by using simple logic printable discs must be safer than ordinary discs in preventing data corruption because they feature an extra layer. I only use printable discs now (because that's what my DiscPainter uses) but I also use them when labeling a throw away disc with a sharpie.
