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DVD ROT EXPLAINED...

 
 
Philip Traum
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      12-02-2003
After hearing the stories here about people having the same early DVDs
that I do, and claim that there is discoloration or visible defects now
in their DVDs that mine do not have over the same period of time, I
figured out the problem.

A friend of mine bought a few of the same DVDs that I did when I bought
mine. His have the same problems, none of mine do, we bought them
from the same store at the same time.

So, why do some of you have this problem and I don't?

It all has to do with how you take them out of the cases. Many of
you (including my friend) will actually physically BEND the DVD when it
does not easily come off of that center holder until you force it to
come flying off! This constant BENDING of the DVD is what is causing
the glue holding the two layers of the disc together to stress out and
give way. I am careful to make sure I NEVER bend the disc, and
instead carefully force the center of the case to allow the disc to come
lose, rather than taking it out on the disc. Then I file down the
center or break it so that I will never have trouble getting the disc
out ever again. Some cases are horrible designs, while others just
pop the disc out when you press the center.

Perhaps if you note that your "disc rot" problems are on the DVDs in
which are harder to get out of the cases, and your DVDs in which come
out very easy from the cases don't have any "disc rot" you will see that
I am right. Also take more notice of how you are actually physically
bending the disc when you try to remove it like I see so many people do.

It is only obvious that bending the DVD is going to stress out the glue
holding the layers together and end up with the mess you have.
Eventually, the two layers are going to separate completely if you don't
treat your DVDs with more care.



 
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Nic
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Posts: n/a
 
      12-02-2003

"Philip Traum" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> After hearing the stories here about people having the same early DVDs
> that I do, and claim that there is discoloration or visible defects now
> in their DVDs that mine do not have over the same period of time, I
> figured out the problem.
>
> A friend of mine bought a few of the same DVDs that I did when I bought
> mine. His have the same problems, none of mine do, we bought them
> from the same store at the same time.
>
> So, why do some of you have this problem and I don't?
>
> It all has to do with how you take them out of the cases. Many of
> you (including my friend) will actually physically BEND the DVD when it
> does not easily come off of that center holder until you force it to
> come flying off! This constant BENDING of the DVD is what is causing
> the glue holding the two layers of the disc together to stress out and
> give way. I am careful to make sure I NEVER bend the disc, and
> instead carefully force the center of the case to allow the disc to come
> lose, rather than taking it out on the disc. Then I file down the
> center or break it so that I will never have trouble getting the disc
> out ever again. Some cases are horrible designs, while others just
> pop the disc out when you press the center.
>
> Perhaps if you note that your "disc rot" problems are on the DVDs in
> which are harder to get out of the cases, and your DVDs in which come
> out very easy from the cases don't have any "disc rot" you will see that
> I am right. Also take more notice of how you are actually physically
> bending the disc when you try to remove it like I see so many people do.
>
> It is only obvious that bending the DVD is going to stress out the glue
> holding the layers together and end up with the mess you have.
> Eventually, the two layers are going to separate completely if you don't
> treat your DVDs with more care.



I don't bend discs and have one disc that had rotted. It is bad
manufacturing not bending. I even replace crap cases with better ones (plus
replace cardboard digipacks).


---
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Mark W
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Posts: n/a
 
      12-02-2003

"Philip Traum" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> After hearing the stories here about people having the same early DVDs
> that I do, and claim that there is discoloration or visible defects now
> in their DVDs that mine do not have over the same period of time, I
> figured out the problem.
>
> A friend of mine bought a few of the same DVDs that I did when I bought
> mine. His have the same problems, none of mine do, we bought them
> from the same store at the same time.
>
> So, why do some of you have this problem and I don't?
>
> It all has to do with how you take them out of the cases.



What the hell? You mean you take them out and watch them??

The only way to stop the rot is to leave the disc where it belongs, in the
case, preferably shrink wrapped.

The satisfaction of owning a movie far outweighs the fleeting pleasure of
watching it, I can assure you.



PS is it only me that buys DVDs and never gets round to watching them???


 
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Justin
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      12-02-2003
Mark W wrote on [Tue, 2 Dec 2003 21:44:10 -0000]:
>
>
> PS is it only me that buys DVDs and never gets round to watching them???


No.... but we do take the shrinkwrap off them, unlike some friends we
have
 
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Codswallop
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Posts: n/a
 
      12-02-2003
On Tue, 02 Dec 2003 21:58:48 GMT, Justin wrote in alt.video.dvd:

>> PS is it only me that buys DVDs and never gets round to watching
>> them???

>
> No.... but we do take the shrinkwrap off them, unlike some friends we
> have


We only take the shrinkwrap off when we get around to watching the DVD,
just in case we change our mind and decide it was a dumb idea buying
that particular DVD (we've never sold any .

--
- Cods

http://www.velocityreviews.com/forums/(E-Mail Removed)
(un ROT-13 to email)
 
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Scot Gardner
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      12-03-2003
"Philip Traum" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

<<It all has to do with how you take them out of the cases. Many of you
(including my friend) will actually physically BEND the DVD when it does
not easily come off of that center holder until you force it to
come flying off! This constant BENDING of the DVD is what is causing the
glue holding the two layers of the disc together to stress out and give
way.>>

Your "bending" theory sounds good. However, it doesn't explain why the
vast majority of rotted DVD titles were pressed by Warner. I agree,
there have been some DVD cases which have required that the DVD be
literally pried from the center hub in order to get it out. Still, if
carefully done, an extremely-difficult DVD extraction can be done
without any severe bending of the disk.

<<I am careful to make sure I NEVER bend the disc, and instead carefully
force the center of the case to allow the disc to come lose, rather than
taking it out on the disc. Then I file down the center or break it so
that I will never have trouble getting the disc out ever again. Some
cases are horrible designs, while others just pop the disc out when you
press the center.>>

I agree, some DVD cases are an abomination. None of my DVDs, with the
exception of a few secondary-disks with extra features, is ever returned
to the original case. Nearly all of my DVDs find a permanent home in
"slim" CD jewell cases, and 4 of them can be stored in an inch of shelf
space.

Here is a more-logical DVD Rot explanation:

Those in this newsgroup who have not yet experienced DVD rot remain
skeptical and discourage any discussion of this subject. I have been
dealing with DVD rot since I first posted my experience with_Cabaret_in
December, 1999. It was inevitable that as the proliferation of DVD
players increased, more and more people would discover that they have
rotted DVDs in their collections.

First, let's not confuse Laser Rot with DVD rot:

LaserDiscs are subject to what's commonly called Laser Rot: the
deterioration of the aluminum layer due to oxidation or other chemical
change. This often results from the use of insufficiently pure aluminum
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). Deterioration of the data layer can be caused by
chemical contaminants or gasses in the glue, or by moisture that
penetrates the acrylic substrates.

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.

It's too early to know for sure, but DVDs will probably have few laser
rot problems. There have been reports of a few discs going bad, possibly
due to poor adhesive, chemical reactions, or oxidation of the aluminum
layer.

http://www.dvddemystified.com/dvdfaq.html#1.24

So far, it appears that the DVD rot problem affects only the second
layer of RSDL (Reverse Spiral Dual Layer) and possibly some DL (Dual
Layer) disks and that, before the layer change triggers the transition
of the optical assembly to focus the laser on the second layer, there is
no breakup in the picture. But, once the layer change occurs, the
momentary freezing, blocking and color blotching begins. I have noted
that as the disks absorb the residual heat from my player, the problems
intensify. I am still exploring this heat-related theory: Heat causes
expansion. Therefore, could it be that the second layer of some WAMO
RSDL disks expands separately from the first layer causing the data
spiral to become out of round?

This peculiar ailment -- most often found on the second layer of Warner
DVDs (WAMO produced RSDL and possibly some DL) disks) -- has been called
disk rot by some. So far, I have lost 5 Warner RSDL titles to this
ailment (_Cabaret_, _Casablanca_, _The Maltese Falcon_, _
Devil's Advocate_ and _My Fair Lady_, however, none of the replacement
disks has rotted, yet.

On Nov. 7, 2000 Mr. Moody posted the best theory that I have heard on
the subject of DVD rot under the subject header: "Re: YES!!! Some screen
caputres from my Pioneer DV-525"

The pictures of the rotted discs at
http://www.mindspring.com/~yerington/
strongly remind me of stress cracks in acrylic. Has anyone ever seen
what happens to a sheet of acrylic which is subjected to continuous
flexing & vibration? It develops numerous short, tiny cracks in the
plastic in the area of greatest stress.

Combine this with Scot's heat observations, and I think what is
happening is that multiple heat cycles are stressing and cracking the
glue holding the layers together. WAMO had/has some defective glue that
is either too brittle or has the wrong heat expansion index (ie
different from the polycarbonate layer) and slowly develops microscopic
cracks as it is repeatedly heated and cooled.

### (My heat observations are posted below.)

This could explain why some people have several discs with this problem
while others have none. Personally, _The Matrix_ is the only disc
mentioned which I have played more than 2-3 times.

This would mean that, unlike LD, DVD rotters will never rot on the
shelf, but only after they are played enough times. This is also
horrifying to think that maybe most or all of us own discs with limited
plays in them and don't know it.

***

Therefore, the un-played defective disks can sit dormant on a warehouse
shelf and still deliver a honeymoon-fresh initial picture when they are
sold months or even years later. If Mr. Moody's theory is correct, it
would mean that it is the heat and centrifugal force of the playback
process that is combining to tear apart and/or alter the second layer of
the disk. He may be on to something here because it is at the outer
edge of the disk, where the layer change occurs, that the centrifugal
force is the strongest.

### Please check your copy of My Fair Lady. Mine has a totally rotted
second layer. Here are the numbers (some of them printed backward)
from the play side of this totally ruined disk:

WAMO VB01

16668V2

IFPI L906

M1S4

The layer change occurs at 1:41:49 right after the intermission and at
the start of chapter 31. The first symptoms of rot were audio dropouts
followed by slight pixelation, then the disk began to freeze slightly
before jumping back to the beginning of the layer change. This was after
playing the disk completely cold out of the box.

The disk warmed up after playing for 10 minutes and the momentary
freezing, blocking and color blotching became worse and worse. Then the
disk began to hang up about three minutes into chapter 31 and then the
player refused to go any further on its own. I could manually jump
through to chapter 35, but the playback problems become even worse to
the point that the disk became unplayable. The entire second layer of
this disk is completely rotted!

This heat theory might go a long way in explaining why a disk that has
rotted performs flawlessly, when you later play only the bad part in
another machine, before allowing it to warm up.



 
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Glenn \(SBfan2000\)
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Posts: n/a
 
      12-03-2003
Ive got tons I havn't watched!
"Codswallop" <(E-Mail Removed)> wrote in message
news:Xns944665971C5B5codswallopcom@139.132.1.4...
> On Tue, 02 Dec 2003 21:58:48 GMT, Justin wrote in alt.video.dvd:
>
> >> PS is it only me that buys DVDs and never gets round to watching
> >> them???

> >
> > No.... but we do take the shrinkwrap off them, unlike some friends we
> > have

>
> We only take the shrinkwrap off when we get around to watching the DVD,
> just in case we change our mind and decide it was a dumb idea buying
> that particular DVD (we've never sold any .
>
> --
> - Cods
>
> (E-Mail Removed)
> (un ROT-13 to email)



 
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Rohan Byrnes
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Posts: n/a
 
      12-03-2003
Hi Philip,

This is a repost of an article I posted up a couple of days back under another
thread. It's quite long, but I hope you find it of interest.

Begin repost --->

Firstly, the term "DVD rot". This term is a bit of a misnomer. DVD discs do
not actually "rot", although in some rare cases it does appear that they can
deteriorate to the point of unplayability. "Rot" actually means to "decay as a
result of bacterial or fungal action" and there is no evidence to suggest any
involvement of bacterial or fungal action in the deterioration of a DVD.

Secondly, the term "DVD rot" is used to describe several completely different
types of manufacturing problems. These problems include - "clouding" or
"ghosting"; delamination (layer separation) and corrosion. I stress again that
these are three completely seperate problems with completely seperate
mechanisms.

"Clouding" or "ghosting" is the result of inadequate cooling of the moulded
polycarbonate substrate during manufacture. The result is 'smearing' of the
pit structure when the substrate is removed from the mould. Microscopic
smearing of the pits manifests itself as a stain on the disc surface which can
be seen under reflected light. In the optical disc industry this staining is
referred to as 'smearing', 'clouding', 'sticking' or 'ghosting' and can happen
with CDs as well as DVDs. Visible disc staining, although unsightly, *rarely*
affects playback of the content.

Delamination or layer seperation. This can happen in one of two ways. The
first most obvious way is through excessive force placed on the centre hub of
the disc. This can be due to heavy handed users, or poorly designed cases that
require more force than normal to remove the disc (or a combination of the
two). The result is excessive bending/flexing of the disc which can crack the
inner hub and, in the worst case, effectively pull the two layers apart. The
second way delamination can occur is if the adhesive layer is not cured to the
full bonding strength during manufacture. The resulting disc will be
mechanically weak and may 'self-delaminate' slowly over time (under normal
loading conditions).

Delamination manifests itself as a dark "stain" around the inner hub, or in
the case of a severe delamination, a series of light and dark rings like "tree
rings". These visible markings are frequently described as a "coffee stain"
and frequently mistaken for "rot" - but they are neither. They are actually
interference rings, sometimes also referred to as Newton's rings and are the
result of constructive and destructive interference of reflected light as it
passes through the air gap that is now present between the two layers.
Finally, delamination of a DVD has the effect of rendering both layers of the
disc unreadable and is therefore catastrophic.

Then there is corrosion. Corrosion of a DVD can happen in one of two ways.
Firstly, corrodants (moisture, oxygen) can enter a disc at the outside edge if
the disc edge is poorly sealed during manufacture. The second way corrosion
can occur is much more mysterious, still not fully understood and seems to
only affect dual layer discs. This second type of corrosion occurs on a
microscopic level and appears to be the result of a rate controlled chemical
reaction between the bonding adhesive itself and the reflective aluminium
coating of the second layer. The reflective coating of the first layer is
usually gold or silicon, which are both chemically inert and will therefore
not react or corrode. The end result in time is a disc in which content on the
first layer continues to playback perfectly, while content on the second layer
is corrupted. It should also be noted that since the reaction occurs on a
microscopic level, outwardly to the human eye the disc will appear to be in
perfect condition.

Available information tends to suggest that this second type of corrosion can
occur when there is a chemical imbalance in the bonding adhesive during
manufacture. However, if it was as simple as that the problem would also occur
in single layer discs as they use the same bonding adhesives and aluminium for
the reflective layer. So what is different about dual layer discs that makes
them susceptible to this type of reaction, while single layer discs are
seemingly not affected? The answer could be in the presence of the gold. I
have read at least one optical industry paper which alluded to the potential
for a "battery effect" to occur between the gold and the aluminium. The paper
indicated that under certain conditions the adhesive itself could act as a
"leading wire" effectively providing electrical contact between the gold and
the aluminium, resulting in accelerated oxidation of the aluminium.

Just as a final comment I would like to address the issue of the extent of
these problems. Unfortunately, there is no hard evidence to go by. However,
taking into consideration the *millions* of discs manufactured each year
around the world and the anecdotal evidence available, I would suggest that
the percentage of discs affected is probably less than 0.01% - and mainly in
discs manufactured in the 1998 to 2000 timeframe (manufacturing processes have
improved considerably since then). Figures suggesting that 10% of discs are
affected appear to be coming from the rental industry whose cliental are
notoriously abusive of the media they handle.

Best wishes,

Rohan.
 
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Bill
Guest
Posts: n/a
 
      12-03-2003
Same here...it's an old family tradition, I guess. My father used to get
Reader's Digest condensed books and not even take some of them out of their
protective cardboard container...at least I do remove the shrinkwrap from
all of my DVDs. : )

"Glenn (SBfan2000)" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Ive got tons I havn't watched!
> "Codswallop" <(E-Mail Removed)> wrote in message
> news:Xns944665971C5B5codswallopcom@139.132.1.4...
> > On Tue, 02 Dec 2003 21:58:48 GMT, Justin wrote in alt.video.dvd:
> >
> > >> PS is it only me that buys DVDs and never gets round to watching
> > >> them???
> > >
> > > No.... but we do take the shrinkwrap off them, unlike some friends we
> > > have

> >
> > We only take the shrinkwrap off when we get around to watching the DVD,
> > just in case we change our mind and decide it was a dumb idea buying
> > that particular DVD (we've never sold any .
> >
> > --
> > - Cods
> >
> > (E-Mail Removed)
> > (un ROT-13 to email)

>
>



 
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Stan Brown
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      12-03-2003
In article <20031202220322.143$(E-Mail Removed)> in
alt.video.dvd, Scot Gardner <(E-Mail Removed)> wrote:
> So far, I have lost 5 Warner RSDL titles to this
>ailment (_Cabaret_, _Casablanca_, _The Maltese Falcon_, _
>Devil's Advocate_ and _My Fair Lady_, however, none of the replacement
>disks has rotted, yet.


How did you obtain these "replacement discs"? Does Warner replace
them when you report the problem?

I've got early /Casablanca/ and /Maltese Falcon/ and have been
waiting nervously.

--
Stan Brown, Oak Road Systems, Cortland County, New York, USA
http://OakRoadSystems.com
DVD FAQ: http://dvddemystified.com/dvdfaq.html
other FAQs: http://oakroadsystems.com/tech/faqget.htm
 
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