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All Forums > Tech Talk > Tech Talk Forum Page 59 > Disk rot?
AuthorPost
sdc
Member

236 Posts
4/03
Posted - Oct 18 2003 : 7:30AM
Apologies to the moderator's if this is in the wrong forum.

I've just noticed that one of my disks - a disk that has functioned perfectly on two or three previous occasions - will no longer play. It's about two years old and there are no visible defects on the playing surface. I've tried it in two players but to no avail. In mine, the disk will spin but not initialize; in my girlfriends, a 'no disk' message is displayed.

Has anyone else had this kind of problem? I've contacted the vendor but don't expect them to be overly concerned about an item that left their hands long ago. I was planning to contact the studio themselves (metro) but can't find an appropriate email address.

Any suggestions?

SDC

Topic Moved by - Gabriel Nine on Oct 19 2003

Gabriel Nine
Senior Member

Firecracker
1273 Posts
8/01
Posted - Oct 19 2003 : 12:47PM
This is more appropriate to Tech Talk.
Flash All-Star Supporter
Golden Age Classic

11018 Posts
5/01
Posted - Oct 19 2003 : 9:17PM
I had an I-Candy disc, Nurses of the 407th, that my JVC stopped playing about a year after I got it, giving a disc read error. Prior it had played the disc fine. I got a Panasonic player about 2 months ago and I popped the disc in and it plays in the Pansonic fine. The JVC still refuses to read it. I can't explain it and this probably doesn't help you much.
Harry Joystick
Member

740 Posts
8/02
Posted - Feb 29 2004 : 11:50AM
Same problem here with the RLD DVD "Just Over Eighteen #1" The disc played perfectly when it was first purchased. Then it wouldn't play on an older DVD player. Now it is unreadable on all of my DVD players.

The disc looks in perfect condition but since it was purchased so long ago, it looks like I'm fucked.

jamesn
Senior Member

Cambridge, MA
750 Posts
1/04
Posted - Mar 3 2004 : 10:09PM
there's a real chance it is "disk rot" not mishandling. cheap media can fail, even if sensibly stored and not played in as little as 1 year. for your own use, taiyo yuden is highly regarded and resold under labels you've heard of like some verbatim discs. memorex is garbage, almost as a rule. if you're truly bored, you can learn about disc "rot" at places like www.cdrinfo.com www.cdrfreaks.com or www.cdrzone.com
 
daviangel
Member

Only time I would buy a girl flowers is if she was in the hospital
455 Posts
1/04
Posted - Mar 8 2004 : 12:26AM
Before DVDs there were laserdiscs (see 2.6), which were occasionally subject to what was commonly called laser rot: the deterioration of the aluminum layer due to oxidation or other chemical change. This usually results from the use of insufficiently pure metal for the reflective coating created during replication, but can be exacerbated by mechanical shear stress due to bending, warping or thermal cycles (the large size of laserdiscs makes them flexible, so that movement along the bond between layers can break the seal -- this is called delamination). Deterioration of the data layer can be caused by chemical contaminants or gases in the glue, or by moisture that penetrates the plastic substrate.

Like laserdiscs, DVDs are made of two platters glued together, but DVDs are more rigid and use newer adhesives. DVDs are molded from polycarbonate, which absorbs about ten times less moisture than the slightly hygroscopic acrylic (PMMA) used for laserdiscs.

DVDs can have delamination problems, partly because some cases or players hold too tightly to the hub. Delamination by itself can cause problems (because the data layer is no longer at the correct distance from the surface) and can also lead to oxidation. Delamination may appear as concentric rings or a "stain" around the hub.

So far DVDs have had few "DVD rot" problems. There have been reports of a few discs going bad, possibly due to delamination, contaminated adhesive, chemical reactions, or oxidation of the reflective layer (see www.mindspring.com/~yerington/ and www.andraste.org/discfault/discfault.htm). The most likely explanation for DVD deterioration is that during the early days of DVD (1997-2000), disc manufacturing processes and materials were not as good as they should have been. Many improvements have been made since then, so the minuscule problem has probably become even more minuscule.

There are also occasional reports of "cloudiness" or "milkiness" in DVDs, which can be caused by improper replication. An example is when the molten plastic cools off too fast or isn't under enough pressure to completely fill all the bumps in the mold (see this archived article from TapeDisc Business for more). Minimal clouding doesn't hurt playback and doesn't seem to deteriorate. If you can see something with your naked eye it is probably not oxidation or other deterioration.

The result of deterioration is that a disc which played perfectly when it was new develops problems later, such as skipping, freezing, or picture breakup. If a disc seems to go bad, make sure it's not dirty, scratched, or warped (see 1.39). Try cleaning it and try playing it in other players. If the disc consistently has problems, it may have deteriorated. If so, there's nothing you can do to fix it, so you should try to get a replacement from the supplier
personally all the problems I've encountered with dvd's have been due to obvious scrathing or scratches on dvd.




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