Be wary of anyone who says bit or disc rot is a myth or not as bad

[NinMicroSega]

Because it is actually a serious problem for most of the Sega CD's library (and a rampant problem for Dreamcast, PS1, and GameCube).

The people who are saying it's a myth are ignorant to the situation and don't understand that the lacquer that Sega used in the printing process was absolute garbage. That shiny data layer is directly under the label of each disc and eventually results in specks that flake off, rendering the whole disc useless. Flaking could happen from just a simple wipe from a Uvex eyeglass cleaning wipe. These game discs are approaching 30 years old. Expecting them to continue to hold up is only leading to false hope.

As for the people saying it's not as bad as it's made out to be, they're full of it. It's actually a serious problem that's in the making. I'd go so far as to guess at least 30% of game discs in the wild from libraries notorious for this problem (SCD, PS1, GCN, etc.) have something wrong with them, and that number will only continue to grow as time goes on.

I've already received a couple of PS1 discs from eBay recently that were DOA, and countless discs for different systems over the years that I've had to send back.

Interestingly, I've also received several PC Engine CD-ROM² games in the mail recently from bad conditions (water damage and the like), and their shiny data layer is miraculously still intact. So this growing situation is dependent on how cheap the manufacturer was with printing the game discs, and I guess NEC was one of the good ones (but don't quote me on that because I may have just been really lucky).

Here are examples of disc rot in picture form for the newbies who happen to come across this thread-

040505_discrot_hmed_1p.nbcnews-fp-1200-630.jpg
maxresdefault (2).jpg
hqdefault (1).jpg

(not my pics)


So yeah. Stop misleading people, otherwise I'll have to hunt you down and throat punch you.

(kidding)

[Cafeman]

I wonder if light accelerates the discs rotting away. I keep my Sega CD, Saturn, and DC games in disc wallets.Dark. Although several discs visually show patterns of some sort of aging, they all work, every one of them.

[Baloo]

When I worked at a video game store back in 2012, we were seeing tons of bit rot/disc rot. The topic does have its own Wikipedia article these days, and it seems that it affects certain manufacturers more than others, notably Warner Brothers HD-DVDs and some Laserdiscs from a specific factory. Nothing is meant to last forever, but it is concerning. I am curious to know what causes it as well, I thought it was a chemical reaction of some kind based on how the disc is pressed, like oxidation of metal.

[Gryson]

One problem is that it's not clear (at least, not that I've heard) what factors cause or accelerate the issues seen in the photos. For all we know, they could have had a ton of abrasive damage, or been exposed to humid air or heat for a long period of time. I don't think it's surprising that if a disc is treated like crap it will fall apart.

The question is: If I store and treat the CDs well, will they still end up with disc rot? In other words, what are that factors that contribute to disc rot that should be avoided? Obviously, abrasion, heat, and light should be avoided, but does oxidation play a role?

The internet is full of photos of disc rot and people saying their CDs were destroyed after sitting in storage for 20 years, but it's never clear what the conditions of the storage were or what the conditions of the CDs were before they went into storage.

I don't mean to deny disc rot - just wish the causes were more clearly understood.

[Silanda]

One problem is that it's not clear (at least, not that I've heard) what factors cause or accelerate the issues seen in the photos. For all we know, they could have had a ton of abrasive damage, or been exposed to humid air or heat for a long period of time. I don't think it's surprising that if a disc is treated like crap it will fall apart.

The question is: If I store and treat the CDs well, will they still end up with disc rot? In other words, what are that factors that contribute to disc rot that should be avoided? Obviously, abrasion, heat, and light should be avoided, but does oxidation play a role?

The internet is full of photos of disc rot and people saying their CDs were destroyed after sitting in storage for 20 years, but it's never clear what the conditions of the storage were or what the conditions of the CDs were before they went into storage.

I don't mean to deny disc rot - just wish the causes were more clearly understood.

All I can say is that no CD that I've owned from new appears to have visibly deteriorated in an obvious way, and they're all kept in their cases in the house and not exposed to excess temperature or humidity. Some seem to have had pinholes from manufacture which could give the illusion of disc rot if I didn't know they were there before hand. I have no way of knowing about changes in their read error rate however.

I maintain that poor treatment or poor storage conditions are the largest causes of what's being called rot. Exposure to moisture, chemicals, or high temperatures for example. I encountered a Playstation disc where the metal layer appeared to have been almost completely corroded, and the only thing I can assume is that some kind of perhaps mildly corrosive or acidic liquid got on the disc at some point, wasn't properly cleaned off, and ate the metal over time. AFAIK that top lacquer layer is slightly porous and that might also contribute to increased prevalence of deterioration in hot and humid countries. I suspect that my collection in the UK is likely to last longer than someone's in Singapore, for example, due to there being less moisture in the air.

Another thing is that it's only natural for people to place discs down on the label side given that you would logically want to avoid scratches to the side that the laser reads, and that leaves the microscopically thin lacquer layer extremely vulnerable to damage unless there's a label covering the entire top side. Most of the problems I see in discs I've bought appear to have been caused by physical damage to the top side, and pinholes/scratches seem far less common in discs with labels that completely cover the top side. The way CDs were constructed was rather dumb in how unprotected the reflective layer was. DVDs and Blu Rays don't have that problem, but there is the risk of delamination in multi-layer discs. Good luck finding working four layer DVD-18s, they were really prone to becoming unreadable over time (and not much time in my experience).

That been said, I've noticed another type of damage that seems to particularly affect discs with a lot of the top lacquer layer exposed: pinholes associated with tiny indentations in the lacquer that don't appear to have been caused by physical damage (though it's not impossible). Is the lacquer deteriorating over time? Were the holes there from manufacture (my VF3tb UK launch disc has always looked like Swiss cheese, for example)? I honestly don't know.

It looks like there have been some studies done into CD longevity: https://www.loc.gov/preservation/sci...longevity.html

[NinMicroSega]

There's a software out there that does data checks on discs called DICUI-

http://wiki.redump.org/index.php?tit..._Guide_(DICUI)


As for what causes it, it's simply oxidation. The only possible way to prevent it from happening entirely would be to vacuum seal your discs, but that doesn't seem convenient.

I wonder if light accelerates the discs rotting away. I keep my Sega CD, Saturn, and DC games in disc wallets.Dark. Although several discs visually show patterns of some sort of aging, they all work, every one of them.

I would argue that even the disc-reading lasers contribute to this problem. How do you think data is written to CD-Rs/CD-RWs/DVD-Rs/etc.?

[Blades]

I would also like to know more about this. The principle is that CDs are already “vacuum sealed” at the factory. The question is whether this protective layer wears off and leaves the data layer vulnerable to degradation. Handling may come into play here.

I can’t say I’ve ever experienced disc rot, but I’d be interested in checking my library.

[Silanda]

I would argue that even the disc-reading lasers contribute to this problem. How do you think data is written to CD-Rs/CD-RWs/DVD-Rs/etc.?

Using dyes and phase changing materials that are designed to absorb specific wavelengths of light. Things which are not present in CD or DVD-ROM discs where the pits and lands are pressed into the polycarbonate. I've never seen any evidence that a correctly functioning disc reading laser will damage the reflective layer or polycarbonate of a disc in a realistic amount of time.

The writing is done using heating, and I'm not sure what would happen if a disc was exposed to a writing laser for an extended period of time, but that shouldn't ever happen.

[GohanX]

One problem is that it's not clear (at least, not that I've heard) what factors cause or accelerate the issues seen in the photos. For all we know, they could have had a ton of abrasive damage, or been exposed to humid air or heat for a long period of time. I don't think it's surprising that if a disc is treated like crap it will fall apart.

The question is: If I store and treat the CDs well, will they still end up with disc rot? In other words, what are that factors that contribute to disc rot that should be avoided? Obviously, abrasion, heat, and light should be avoided, but does oxidation play a role?

The internet is full of photos of disc rot and people saying their CDs were destroyed after sitting in storage for 20 years, but it's never clear what the conditions of the storage were or what the conditions of the CDs were before they went into storage.

I don't mean to deny disc rot - just wish the causes were more clearly understood.

These are the big questions that have yet to be answered. I bought the majority of my CD based games back when the systems were current, and have never had a disc with rot issues. But that doesn't mean that the rot isn't a thing that exists. Personally, I wouldn't be spending large amounts of money on any disc based media at this point. I don't believe discs are going to last virtually forever like cartridges seem to.

[cleeg]

Now as far as how the data is written to a factory pressed CD it is actually written to the top of the plastic as a series of pits and lands (I saw this on YT's Techmoan) and then lacquered. If we imagine the disc label side down on a surface it would be made like this:

Plastic layer one with sprayed on label.
Shiny reflective layer of aluminium foil.
Plastic layer two onto which pits and lands of data are etched.
Lacquer layer.

I wonder if for CDs the rotted parts are disallowing the (? still intact) data to be read due to light's being impeded by degraded foil? Maybe it would be possible to split the layers and add new foil, as I imagine (barring big scrathes and stuff) that the data would be safe on its own layer? Or maybe a different fix?

I know that DVDs have their data stored elsewhere on the disc, and wouldn't know where it is kept on a GDROM, so I imagine any rot there is a different prospect entirely, but I suppose there might be a fix for CDs at least.

As far as humidity, I think CDs are good in humid weather, I read somewhere that CD videos did so well for so long in Asia because they faired well against the VHS competition, which was affected badly by the higher humidity in that part of the world, so I wonder also if it could be blamed for CD rot when they seem to have a good record of not being affected?

[NinMicroSega]

As far as humidity, I think CDs are good in humid weather, I read somewhere that CD videos did so well for so long in Asia because they faired well against the VHS competition, which was affected badly by the higher humidity in that part of the world, so I wonder also if it could be blamed for CD rot when they seem to have a good record of not being affected?

That's entirely dependent on the manufacturer. As I said earlier, PC Engine CD-ROM² discs seemingly handle moisture well, and are overall better quality. However, I don't think the same can be said for most Sega CD discs.

[Gentlegamer]

These are the big questions that have yet to be answered. I bought the majority of my CD based games back when the systems were current, and have never had a disc with rot issues. But that doesn't mean that the rot isn't a thing that exists. Personally, I wouldn't be spending large amounts of money on any disc based media at this point. I don't believe discs are going to last virtually forever like cartridges seem to.

This is where I arrived at a while back. And though I'm not quite there, it's what's leading me to switch to emulation only for classic gaming at some point.

[TrekkiesUnite118]

It's not that the lacquer is cheap or that it's rotting. It's just that it's easier to damage than you want to admit. Most Sega CD and Saturn games being bought and sold these days are second hand, and they are most likely disc only or in a replacement case. Which means they spent a good part of their life without any case to protect them and were carelessly thrown around/beat up. That's going to cause damage to the top layer like you're seeing. Disc Rot in and of itself isn't really the same thing as pinholes/top layer damage. People need to stop conflating the two.

The reason people like myself are dismissive of the disc rot panic is because I have over 100 Saturn games and quite a few Sega CD and Dreamcast games and the only ones that have this problem are the used ones I bought that already had them. I've paid attention to them over the years and no new holes have formed, and the data is all still there and accounted for. I even have a copy of Megaman 8 I got for $20 that is full of pin holes. Yet when I rip the disc as recently as a month ago and compare the checksum to the redump checksum, I find it still matches. The reasons for this are because for one, the metal layer is the reflective layer, not the data layer. The Data is etched into the plastic so it's still there and some drives are able to still read it. The other part of this that people seem to overlook is that the CD-ROM format has a very robust form of error correction built into it. So even a disc that's pretty badly damaged can still be read successfully.

It also doesn't help that the people fueling this panic never once take the time to reflect on any of their actions that could have also at least partially caused the issue they're seeing. They just want to write it off as a form of rot and wash their hands of any responsibility. They don't want to own up to the fact that they or a previous owner may have mishandled the disc at some point, may have tried to clean it with something that ended up being caustic, or may have improperly stored it. All of which very possibly could have led to the perceived rot.

The other issue with this is that most of the studies out there people point to are talking about CD-Rs, not factory pressed discs. CD-Rs are a different thing all together and those studies should not be conflated with factory pressed discs.

tl;dr, if your discs aren't showing signs of rot after 30 years, they're not going to magically start rotting if you continue to take good care of them. If they do have pinholes, it's not the end of the world either. Make a back up and stop panicking.

[Gryson]

It also doesn't help that the people fueling this panic never once take the time to reflect on any of their actions that could have also at least partially caused the issue they're seeing. They just want to write it off as a form of rot and wash their hands of any responsibility. They don't want to own up to the fact that they or a previous owner may have mishandled the disc at some point, may have tried to clean it with something that ended up being caustic, or may have improperly stored it. All of which very possibly could have led to the perceived rot.

All excellent points. This point in particular reflects my thoughts exactly. I've seen so many poorly stored, poorly cared for consoles, carts, CDs, accessories, etc. over the years (it's a sad fact that some gamers are not known for cleanliness). It's easy to point at some boogeyman called "disc rot" and assign all problems to it, but the fact is, CDs are fragile and they aren't always treated with care.

I want to see more work done the way you describe - comparing checksums across time, monitoring storage methods, and so on.

Anecdotes based on ebay purchases aren't really helpful here.

[Mega Drive Bowlsey]

I've heard of disc rot but never experienced it happening to any CD based games in my collection, which includes Mega CD, Saturn, and Dreamcast titles. I've always taken very good care of my games and, while I'm not denying that disc rot exists, like a few guys here I'm more inclined to put the blame on most CD based game problems being a case of poor treatment and crappy storage over time.