Help me understand "CD rot"

[Jazz]

I have one disc that had the original rot problem as you describe. There is nothing visible at all. I should try under a microscope or good magnifier, as sometimes the discoloration was literally microscopic.

That original outbreak was at a UK plant, as you say, and randomly affected a quite large percentage of its output over time. The fault can still happen to isolated discs today, but is very rare.

The other issue that still turns up quite often is when something is off-centre. That can cause the head motor to track hard and become very noisy, or if the whole disc is off centre, the disc can become stuck (and you can't tell easily) or can be bashed against the drive housing and shatter: I've seen the result of that happening with a disc that had to be used for an expensive computer application and shattered in a Mac drive, jamming the drawer in the process.

There are non standard discs out there that are too thick as well - these can also jam in some computer type drives including some of the external USB drives, and still play happily in a CD/DVD/Blu-ray player as the OP described.

Finally, there are discs with non-standard centre holes. I dealt with one disc that slipped when played on some standard players. In this case I found a laptop drive that would grab the disc and ripped it.

CD-RW discs in particular can have a short life, unless stored in complete darkness or are regularly reused.

Geeze, in my decades of using audio CDs on an early 1980s Sony player, then mid 90s Phillips CD player, then in many Mac DV-R players, now a cheap LG USB on a Mac and; countless CD-R and CD-RW disks from students (always sketchy, cheap disks) from 2000 to 2016; and dozens of DVD rentals in a Panasonic DVD player, then Sony CD/DVD player, and then DVD/BR disks in a Sony BR player: I have never, ever, ever had any of the issue you described nor heard of them from anyone. I still use the Phillips, Sony CD/DVD, and Sony BR players to play music CDs.

 

[Galliardist]

Geeze, in my decades of using audio CDs on an early 1980s Sony player, then mid 90s Phillips CD player, then in many Mac DV-R players, now a cheap LG USB on a Mac and; countless CD-R and CD-RW disks from students (always sketchy, cheap disks) from 2000 to 2016; and dozens of DVD rentals in a Panasonic DVD player, then Sony CD/DVD player, and then DVD/BR disks in a Sony BR player: I have never, ever, ever had any of the issue you described nor heard of them from anyone. I still use the Phillips, Sony CD/DVD, and Sony BR players to play music CDs.

I know I make it sound like CD could be a litany of disaster, but I've seen something like 20 bad discs in forty years, two of which were my own.

To put it another way, someone I know who's worked in record shops at different times, says that CD returns were incredibly rare, and the return of vinyl means handling a couple of returned LPs a week.

Or, again, if you read audiophile forums, failing CD players are a bigger thing than bad CDs.

However, the question is about a badly behaved CD so a list of candidate faults is what's needed.

 

[pablolie]

The only issue I have ever had with CDs was due to surface abrasions. The ones that cause issues are not always visible. I have been able to rip CDs that had hiccups with whitening toothpaste. But if it's too scratched, no error correction will help.

I agree with those who say the major issue is CD players/drives. They include many mechanical elements after all. I. must also confessed that if I'd invented the CD I'd prefer the reader to point down rather than up (dust deposits over time etc.).

 

[pseudoid]

this

CD rot was a short hype several years after their introduction but was caused by using bad materials.

This "CD-rot" problem was associated with recordable CDs (CD-R or CD-RW).
If memory serves me corectly, pre-recorded (pressing-process) CDs were not afflicted with rotten cd-rot.

That having been discussed already (by @JSmith ); the possible physical-damage (which leads to error detection/correction attempt) is usually due to abuse of the label side of the CD. Since the reading surface is heavily protected by the thick polycorbanate layer.
In the case of the CD-R related CD-rot, it is usually best to always keep them away from light exposure.
One of the older CD transcoders (I think it was dBPowerAmp), which would first read the entire CD and create an overall data hash value to compare with hash value in a database... I think the database used to be part of the cddb, which got absorbed by GraceNote [?].
Some used to swear by green Sharpie'ing the outer edge of CD-Rs (YMMV)

 

[Philbo King]

I recall from the 90s a reported rash of CD-R disc failures for discs exposed to sunlight. It was theorized the dyes used in early writable CD-Rs would decay.

 

[Galliardist]

I recall from the 90s a reported rash of CD-R disc failures for discs exposed to sunlight. It was theorized the dyes used in early writable CD-Rs would decay.

All the dyes in CD-R and CD-RW are light sensitive, and recordings have a life of typically a few years if not kept in darkness. Some brands noted or claimed a longer lifespan on their discs. We did have one disc that I didn't pay attention to or realise was a CD-R until I went to rip it and found I couldn't!

If you have archived CD-Rs or RWs, it's probably a good idea to rip them now, before it's too late.

 

[Galliardist]

this

This "CD-rot" problem was associated with recordable CDs (CD-R or CD-RW).
If memory serves me corectly, pre-recorded (pressing-process) CDs were not afflicted with rotten cd-rot.

That having been discussed already (by @JSmith ); the possible physical-damage (which leads to error detection/correction attempt) is usually due to abuse of the label side of the CD. Since the reading surface is heavily protected by the thick polycorbanate layer.
In the case of the CD-R related CD-rot, it is usually best to always keep them away from light exposure.
One of the older CD transcoders (I think it was dBPowerAmp), which would first read the entire CD and create an overall data hash value to compare with hash value in a database... I think the database used to be part of the cddb, which got absorbed by GraceNote [?].
Some used to swear by green Sharpie'ing the outer edge of CD-Rs (YMMV)

The first cases to be named CD rot applied to commercially pressed CDs from some Philips label discs. I have one. The cause was a pressing fault so the disc surface wasn't properly sealed and air got in. This has already been mentioned in the thread.

Exact Audio Copy generates hashes during the copy and checks them at the end if a reference is available. It also captures copies of the hash for successful rips and will store them for unknown discs in a public domain database if you set it up to do that, as well as an associated icon/image if you make one. You have to pay to use GraceNote with EAC if I remember correctly.

Another sideline - Philips and Sony used different processes to print CDs, and that has been blamed for some discs not being readable on the other side's players. Yamaha made a CD writer that burned larger pits than standard to try to improve reading and reliability of CD-Rs. I have no idea if that ever really worked or caused problems.

 

[somebodyelse]

This "CD-rot" problem was associated with recordable CDs (CD-R or CD-RW).
If memory serves me corectly, pre-recorded (pressing-process) CDs were not afflicted with rotten cd-rot.

Post #15 already linked sources documenting the issues with pre-recorded CDs from the PDO Blackburn plant including PDO admitting their production process was the cause.

 

[restorer-john]

Yamaha made a CD writer that burned larger pits than standard to try to improve reading and reliability of CD-Rs. I have no idea if that ever really worked or caused problems.

The Yamaha AMQR CD-R/RW drives and recording system took advantage of the standard which allowed for a +/-x% variation in the constant linear velocity spec. They took the tolerance to the upper limit and that meant pits/lands ended up a bit longer- that's all. You lost about 12 minutes IIRC of recordable total time on a CD-R while still being compatible with RedBook players. The AMQR was switchable if you wanted to experiment.

I have one of their machines (CD-CDR/W HiFi recorder) with an onboard 120GB HDD.

There's no measureable difference with an AMQR recorded CD-R vs a normal CD-R or even the same commercially pressed one, in my tests I did a decade or more ago.