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 The dreaded disc-rot

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laserkb

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PostSubject: The dreaded disc-rot   Sat Apr 02, 2011 9:05 am

Some newer collectors of laserdiscs may, quite rightly, assume that they are dealing with an almost perfect, durable home video format. After all, a laserdisc will perform as well on its 1000th play as on its first. And, for 99.99% of LDs manufactured, this is certainly true.

But there was that sad little moment in the history of the format which should be a lesson to us all. It became known as "speckling" or, more commonly, "disc rot".

In brief, a laserdisc isn't really one disc - it's two sides bonded together with a tough epoxy resin. Occasionally, with some older analogue discs (pre-1990), this glue can corrode from the inside outwards and eat into the encoded layer of the disc itself. This then compromises the playback image (snowy speckles will be seen) and the sound (crackling will occur). Once established, it cannot be cured, it may worsen, and the disc will deteriorate beyond use. Fortunately, the number of discs affected was initially so few as to be statically insignificant.

Then came the day when, at Sony's major pressing plant in Terre Haute, Indiana, someone mixed up a batch of the glue incorrectly and for several months, around 1996-97, LDs were being churned out using this faulty resin. Although no one realised it at the time, a whole slew of titles, mostly for Sony's own Columbia-TriStar releases but also for other companies such as Warner Home Video and Criterion, were being sold with their fate irrevocably sealed. They all played fine at first, but within a couple of years, people started to notice the telltale signs on playback. Disc rot had struck!

Most of the discs produced at this plant at the time could easily be identified. They carried a manufacturing matrix on the gap close to the disc's label, usually LDVS followed by a string of numbers. (Sometimes it said DADC.) The thing to remember is that NOT every disc with these matrices would be affected, and those that were would vary in the extent of the speckling. Sometimes it may be just a few minutes of speckles at the start of playback, possibly one side only, with the rest of the disc being OK. In the worst cases, the signal interference would get so bad that the laser pickup simply would not track properly. Once a disc has degraded to this extent, it is fit for only one place - the bin. (Or you can turn it into a wall clock or something.)

I've certainly had my share of affected LDs and there is a Top 10 (or bottom 10, if you like) of the most infamous titles. Leading the list is ERASER with over 2,000 reported instances of disc rot. Second is AIR FORCE ONE: SPECIAL EDITION, followed by, in descending order, CONTACT: SPECIAL EDITION, LOST HIGHWAY, STARSHIP TROOPERS, UNDER SIEGE 2: DARK TERRITORY, THE CABLE GUY, THE NET, THE GAME and THE PROFESSIONAL. The list also includes big sellers like THE STAR WARS TRILOGY: DEFINITIVE EDITION, FARGO, MEN IN BLACK and other top titles.

The point to remember is that these are all NTSC releases. Where a PAL version was released, such as STARSHIP TROOPERS or AIR FORCE ONE, there is no such problem. Most PAL laserdiscs were pressed either in Austria or Japan where they could get the chemical mix of their glue right! Hardly any PAL titles have been reported with speckling beyond a few of the very oldest analogue LDs, so you can buy PAL discs with confidence.

I'd be really interested to know of collectors who have a rot-free copy of ERASER - I've tried 3 and haven't found one yet. Similarly, I'd love an uncorrupted copy of GHOSTS OF MISSISSIPPI, COPYCAT or DEMOLITION MAN. Anyone got one?


Last edited by laserkb on Sat Apr 02, 2011 6:02 pm; edited 1 time in total
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nissling



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PostSubject: Re: The dreaded disc-rot   Sat Apr 02, 2011 1:08 pm

My copy of The Professional from Columbia is completely rot-free. Lucky for me. ^^
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The LD Hunter

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PostSubject: Re: The dreaded disc-rot   Sun Apr 03, 2011 7:09 am

Maybe I should make that my mission, to find a rot free version on ERASER. LOL
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HippieDalek

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PostSubject: Re: The dreaded disc-rot   Sun Apr 03, 2011 1:06 pm

Interestingly the only disc I have with laser rot is a PAL one. At least I assume it's laser rot, I have a couple of black dots on the disc (it's a 'gold' disc so it really stands out) and when it reaches those points I get a white static like band move up the screen horizontally, like static on a VHS.

The disc is Queen, Live in Budapest.
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SnR

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PostSubject: Re: The dreaded disc-rot   Sun Apr 03, 2011 6:08 pm

Hi again all,

I also have a few discs with rot. but i cant remember all of them:

Angel (1984) side 2 is like a chewed VHS
Striptease (Demi Moore) Side 2 is quite bad at the start but gets better. It would be where she is stripping, Ive wondered if that bit has been watched too much! :-p
2010 (end of side 1 starting to go but still watchable, slight video noise)

I also have a disc where the two sides are starting to separate from each other but i cant remember what it is!
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laserkb

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PostSubject: Gold discs   Sun Apr 03, 2011 6:10 pm

It's interesting that you mention your Queen disc. I have a couple of PAL 'gold' music discs and they, too, don't seem to have weathered as well as regular 'silver' discs. Some of these, such as my ELTON JOHN: TOUR DE FORCE disc, were actually called CD Video discs, and I've noticed that some of the gold plating seems to be coming away, particularly from the edge of the disc. My other 'gold' disc is INXS GREATEST VIDEO HITS and this one is properly called a Laser Disc and bears the LD logo but it still seems to play back with a slightly degraded picture these days (although the sound remains great, much better than its DVD equivalent).

Most of these CD Video discs were manufactured in the 80s (the INXS disc actually came out in 1990) and I've no idea why they were issued 'gold' unless it was purely for aesthetic reasons. A regular disc starts out as a silver glass master on which the encoded signal is written as a series of 'pits' (which I assume was the same for these gold discs) with a more substantial nickel-plating deposited over it. The nickel layer, once it is thick enough, is then carefully stripped away from the glass and is known as the nickel stamper sheet. These stampers can then be used to make up to 25,000 pressings before they have to be 'retired'.

The laserdiscs themselves are actually made from a type of Perspex or plexiglass (polymethyl methacrylate) which is heated and forced under great pressure into two halves of a mould which also holds the nickel stampers. Adding the reflective coating, which allows the laser to read the pattern of pits, is one of the final stages of the manufacturing process. Obviously, these music discs with their gold surfaces seem not be quite as reflective as the silver ones over time.

What you have observed on your Queen disc may not be disc-rot as such but simply the surface coating wearing away. I haven't noticed any 'black dots' as such on gold LDs but I do agree that this process was probably not the best way to make a durable video product - which is why it wasn't used for movies and certainly not used after 1990.

(Strangely, the 'blood red' disc for EVIL DEAD 2 seems to work fine, so what do I know?)
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HippieDalek

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PostSubject: Re: The dreaded disc-rot   Mon Apr 04, 2011 2:23 am

Yeah, this is one of the gold CD Video discs.

Here's a picture of the suspected laser rot (Well...mostly of my ceiling...it's so hard to take a picture of the surface of a disc)




In comparison this is what I usually think of as laser rot (an old CDR I bought in the 90s I recently found)

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MOTLEY1972

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PostSubject: Re: The dreaded disc-rot   Tue Apr 05, 2011 12:41 pm

hi lads first post the funny thing is i have been a laserdisc owner since 1995 and the discs i have kept hold of dont seem to have had any rot problems including the starwars definitive edition boxset which on the laserdisc data base is listed as one to aviod at all costs i am glad mine is ok as it cost me an eye watering £250 quid but since getting back into laserdisc i have bought three discs which had severe rot starship troopers ntsc which was used i know what you did last summer ntsc and disneys robin hood cav edition ntsc the last two brand new and sealed i got robin hood today from the usa with a bunch of other disney laserdisc
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PeaceMaker1

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PostSubject: Re: The dreaded disc-rot   Wed Apr 20, 2011 2:41 pm

Mine is OK...

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