Hello Everyone,

I'm sure you guys have hammered this topic to death, but after reading a few threads from years past I figured I'd try and start discussion again, as I'm sure it's a topic everyone in the community is passionate, or, rather tired of. Either way, I hope it fosters some conversation and doesn't step on too many people's toes.

I have a copy of Star Trek III: The Search for Spock (LV-1621) that has been in pretty bad condition for as long as I've owned it. I recently tried to watch it, only to find that every audio track on the disc was completely destroyed up until around 30-45 minutes into each side, where it went from un-listenable to decipherable. I'm not too broken up about it, but it got me thinking.

The main focus point I wanted to put out there for this conversation is this: Could rot have been prevented? either by the consumer or the producer.

In order to answer this question I need to ask a few more, which I need your help to answer.

1. What causes rot?

- Well, it seems the conclusion is oxygen, as it is an oxidization process that is assumed to result in Laser Rot (from what I understand), which brings us to another question.

2. What is oxidizing? Is anything even oxidizing?

- Is it the silver/aluminum backing that oxidizes and prevents proper optical properties in the plastic from being read by the laser, or is it micro-bubbles within the plastic signal layer which, over the course of weeks, months, years, what have you, come to the surface, "pop" and distort the signal, resulting in noise?

3. Where did the oxygen come from?

- I have heard that discs do not spontaneously develop rot. If they have rot they were bound to have it from the day the disk was produced, and if they exhibit rot signs, they will only get worse, never better, so, if that's the case, where did the oxygen come from? Obviously it came from production, right? It seems it can only have possibly been the result of one or two of the production processes. The way I see it, either the air was trapped between the signal layer and the silver during pressing, which seems more likely, or the air was already in the signal layer as I posited earlier, and comes from microbubbles that were introduced during the induction molding process. Perhaps the oxygen comes from failing adhesives that keep the two sides together. Either way, if oxygen is the cause of Laser Rot it had to be introduced during production, right?

4. Is the disk a perfectly sealed unit?

- Or can oxygen get in over time? If that were the case I imagine every disk would experience rot in a matter of years.

5. Why did it only happen to some discs and not others? What was it about certain facility's production processes caused them to be more notorious for producing disks with rot problems?

- Were they pressing the disks with an insufficient amount of pressure? Were their machines poorly calibrated? Were they injection-molding the disks too fast, or at the wrong temperature? Did they not allow the injection-molded sides enough time to cool? I assume we may never know the answers to these questions. It would be great to get a first-hand account from someone who worked in one of these facilities on what their processes were like and contrast that from those of someone who worked at a different facility, one less prone to producing disks with rot.

So... Could rot have been prevented? I'm sure the answer is yes, but I suppose we still can't answer that question. My initial idea and question was about if it would be possible to store all your discs in a vacuum chamber to prevent rot from developing to further stages. While this is a ridiculous idea with almost no practical application, not to mention extremely expensive, I think I've answered my own question while typing this all out. It seems that the oxygen is trapped inside the disk in one way or another during pressing, and nothing can get it out, making keeping the disks under vacuum completely useless as a means of prevention, unless rot is caused by a failing adhesive layer, in which case, keeping lightly rotted disks under vacuum while not in use would save them from deterioration as the failing adhesive layer would allow for a disk kept in an oxygen rich environment to continue to degrade.

Does anyone else have any opinions or personal hypotheses on the causes and origins of Laser Rot? I'd be interested in hearing them.

Cheers,

-Gary

Good evening petc,

I am writing to compliment you on the way that you write your posts ''of which is a credit to you sir''

I like your style, and your personality and enthusiasm shines through with each message in which you convey each subject.

Here is my little pennies worth in answer to this ROT topic.

Just to say that I have had a few known rotted disc's in my time, and these were purchased secondhand and are the following;

1) THE CABLE GUY
2) FUGITIVE
3) SHAWSHANK REDEMPTION (US) / JAPANESE VERSION IS PERFECT.
4) STAR SHIP TROOPERS (US) / JAPANESE VERSION IS PERFECT.
5) THE EAGLES HELL FREEZES OVER MUSIC DTS (US) SIDE B SOUND POPS / SURROUND SOUND VERSION IS FINE

Pioneer as far as I personally know were the only manufacturer of LASERDISCS who from the mid 90's on had a fully automated production line and that they among others perfected the bonding materials and methods of production.

The other and ''to my mind'' less caring manufacturers didn't give this format 100% attention.....to my mind this was not acceptable.

The same could also be said about DVD's when they first came on the scene with the following points of note:

The consortium of Electronic Manufacturers, movie and distribution DVD members decided to back a smaller format, knowing full well that this would be a compromise, this was ''for all intense & purposes'' for the sake of the consumer, who demanded a smaller and more reasonably priced packaged product, in which to place into their shopping bags ect...ect.....And that I can like others understand.

However around about I would say 30% of the transfers to DVD were not up to scratch, and the sound transfers were a serious compromise compared to Laserdisc...........
This to my mind was a staggering comedown, & was not an improvement but was in fact an inferior product.

Yes they re-released remastered titles, in order to address this problem, and then brought out the SUPERBIT barebones tiles without any extras, to make use of the extra space added to the film bitrate transfer........

To my mind Laserdisc has and is still the bench mark for uncompressed sound.

HD-DVD, Blu-Ray and the the forth coming 4K transfers have come a long way, but at the expense of the true collector, who's true reason for collecting LASERDISC is mostly down to the large disc's, the cover art and the fact that one is able to clearly read what is on the movie label on the back.

Apologies for digressing from the topic sir, and hope you don't mind reading a personal expression, of how much I appreciate Laserdisc..........The last of the true movie packaged media experience.


Kind Regards to you

It was my understanding (from what I have read) that the problem with laserdiscs was due to problems with the adhesives used in some of the runs of discs that held the two halves of the discs together that corrodes the information on the disc from the inside. This was especially true the farther back in the production history which is why discovision releases are so problematic in this regard.

If that is indeed the case I suspect there is nothing that can be done to prevent it on discs where it is going to happen.

I have a handful of discs that are sticky on the edges from glue oozing out - if the glue is getting out I assume oxygen can get in - yet none of these discs have had any rot problems.

petc - How is the video on your star trek disc? If it is ok then I suspect there is some other problem with the disc. Also, the few discs I have that have had rot the problem is throughout the side (or sides) of the disc - and the audio is usually not nearly as affected as the video is.

I remember reading that good storage conditions (~68F, low RH) can stop/stall rot.

I'm sure this would be next to impossible to perform, but since the signal is encoded on the pits and bumps of the injection molded plastic, would it be possible to separate a disc, dissolve or remove the metal backing, and then re-apply and re-adhere the two together? Like I said, I'm sure no one has done this... but it would be very interesting if a process was found which could "De-rot" a disk, and I'm sure there would at least be a small market for that service.

How it would be done... well... That is still nebulous.

I doubt you could take apart the disc halves intact - and if the information is corroded it is likely permanently damaged.

Has anyone here had an image pressing with laser rot? I know they were manufactured in a somewhat different process.

Getting them apart intact would be the kicker, but from what I understand, if it is corrosion that is the issue, the metal used in the discs does not contain any stored information, it is just a backing for the laser to reflect off of when reading the information stored in the pits and bumps of the plastic, which can't corrode.

Take a DVD RW disc and scratch one side of the top coating off and that disc will have tough one for the laser to read it. Comes back as no disc and ejected from player.

I think trying to take a laserdisc apart to clean it up is bit of risk. One splinter hairline crack and it will be useless.

I do not plan to take anything apart, just an interesting thought experiment on how it could potentially be done. Obviously vast R&D would have to go into a reliable and proven method and it would cost more money than it would ever be worth to even figure out how to accomplish the task. But it's interesting to think about how it may be done.

Taking it apart and sticking it back together with the right glue and with equal pressure per square foot or what ever it is they used? Otherwise the risk of spinning it and it came apart will damage the player.

I have one disc that is cracked on one side and had to buy same title again. I'm thinking can I take it apart without making a pigs ear of it? Slipping thin metal object between the disc and prying it apart slowly moving the object around until the two bonded parts come undone without it cracking the other side. I think I'll take a pass on that.

Rot is always an interesting topic, but I'm afraid I cannot add anything useful to this subject.
The only question I can come up with is how people with a large laserdisc collection can be sure, at any time, that none of their discs are affected by rot? It is nearly impossible unless you watch these discs over and over again.
Yet, there must be something that is causing this oxidizing process to speed up, whether it is caused by the climate, temperature or the environment the laserdiscs are stored in.

yes, that's why I know I don't have rot, I watch my discs and don't talk about it

again this is such a moot point that we need to get off the rot topic.
I saw once how CDs are made, no way you can "clean" any of the aluminum if that is the case that causes rot, its just too thin
and will cause damage so you will never be able to play again.

just get a magnifying glass or microscope to look at the differences of a disc with and without rot.

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the rein-o official signature:

I agree. You are thinking about it too much. Discovision and Sony plants aside, rot is not a huge problem. It was always hyped way out of proportion and still is. Since I don't collect Discovison or late US releases rot really only comes to my attention in threads like these.

Like I said, not trying to step on too many people's toes, I'm just interested in what the actual problem was and how it could have been prevented or hypothetically repaired. It's all just a giant thought experiment.

Of my 40+ LaserDiscs, only one has rot to a degree that is troublesome. I know it's not as huge a deal as it was made out to be, but it still doesn't stop me from being interested in it.

Apologies for bringing it up, I suppose.

I think this whole talk about how storing conditions can help prevent rot is a mere theory.

I have bought numerous LDs over the past two years in South East Asia, all stored in the worst conditions
imaginable in a hot, humid climate without AC and nonetheless they all still work pretty much perfectly. I have around 400 LDs in my collections
and only a very small part of them have rot. Most have no rot at all and some have very light rot.

I do not think rot can be prevented. I have a strong feeling that the majority of my LDs will survive me.

I have also heard that the fact that a disc might be affected by light rot does not necessarily mean that it will get
worse in time. It might simply reach a certain level of rot without eventually becoming unplayable.

That's pretty much the same for me. As for me, honestly, I haven't had THAT many problems with "rot". Whenever I do have problems with it, it's usually from DADC USA or very early Laserdiscs.

I had a fair amount of problems with laser rot in the late 90s and early 00s. Man, it was so infuriating whenever I found a title that I had spent US$50+ on the year before that was showing the early stages of rot. Many expletives were professed, and while I'm not litigious by nature, I'm surprised that it never turned into a class-action lawsuit. They say that LD had a US market penetration of about 2% during its heyday. A class-action lawsuit affecting 2% of the American population sounds like a lawyer's wet dream.

I've heard multiple theories about rot -- its origin, causal mechanism, etc. -- many of which have been expressed here. As to the cause, the most common theories were (a) impurities during manufacturing that damaged/oxidized the aluminum layer over time, and (b) an improper seal on the outer edge that allowed oxygen inside, which similarly led to oxidation. I've also heard the rumors that keeping the LDs in a dry, room-temperature environment would stave off rot, but I've always been doubtful about that.

Another prevailing sentiment I've noticed is that rot is born at the factory, and that nothing can be done to a disc afterwards that will lead to rot. I.e., if a disc doesn't show any signs of rot now -- more than a decade after it was manufactured -- then it should be rot-free for the rest of its life. I'm a bit cautious about this claim as well, and have a paranoid concern (but no evidence) that this might not be the case. For example, if the cause of rot is an imperfect seal, it seems plausible that something later could break the seal (such as dropping a disc edge-wise on a hard floor, or rough-handling during shipping) and thus initiate the rot process.

But anyway, in spite of some of the posts to the contrary, I still find it a fun topic to pontificate about.

This disc was pressed by both Pioneer Japan and Pioneer USA in early 1985. This was when Pioneer had many issues with rot, which lasted at least until the end of 1985. Our pressing of this disc only has light rot on Side 1, and nothing more (except from some drop-outs). Also, you didn't report this title to the database yet. It currently has 5 rot reports: 3 light reports, 1 medium report and 1 strong report. Strong rot is when the entire screen is covered with high-frequency speckling, and critical rot is where the audio is disorted as well.

The rot is from both the disc being badly made at the factory and the glue separating and taking the data layer with it, and also extreme environmental damage. I have Smokey and The Bandit on Discovision and 5 mins of the B side is dead. I have some General Motors dealership traning discs from the early 80's and they were found in an abandoned dealership. Some of the sleeves are water damaged and rotted to the point where the ink layer of the cardboard has blistered and is coming apart, some have mold on the disc, and all the plastic "condoms" have obliterated into shreds of confetti. It was a real mess. The nicest shape discs all play but all of them have a fuzzy static like VHS tracking.

I've had old Discovision discs in the past with the same issues of inner sleeves, these are the only crumbling inner sleeves I've
ever personally encountered.

I have discs that were bought new from the late 80s that still have the ECs and no issues crumbling, so this has nothing to do with rot
of picture quality.

I've been spot checking my discs to list on ebay, just haven't watched an LD in quite some time, and none had rot and none have rot.
So if it didn't have rot it didn't get rot, if it has rot it had rot.

So far my collection that I actually watched back in the day is still good