# Strange lines on discs



## adriesba (Dec 30, 2019)

Occasionally I'll get a disc that has these odd lines. They are not scratches (see pictures).

View attachment 140825


View attachment 140826


What causes this? Is it bad?

I can't seem to find any info about this on the internet.

Let me know if the pictures don't show it clearly. Click them for better resolution.


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## Joe B (Aug 10, 2017)

This article will give you more information on this than you really want to know:

*The Hidden Phenomenon That Could Ruin Your Old Discs*

I have had an entire 5 season show (DVD) bronze on me after 7 or 8 years. The damage appeared on all the discs in the same spot (looked like big coffee stains), an obvious manufacturing problem. I have had CD's which have played perfectly for 30 years suddenly develop 'pits', which look like holes right through the aluminum layer. This is very disheartening when it happens. Some people have never had any bad luck with this, and I suspect it is because of where the discs were manufactured. These defects are all problems with the manufacturing process, which the article gets into.
The discs will often play for a while because the error correction used on players can 'substitute' enough information to continue playback. At some point the damage becomes too extensive for error correction and playback will cease.

edit - another good article here:

https://www.soundandvision.com/content/cd-rot-rack-and-ruin


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## Guest (Aug 4, 2020)

Very depressing. I've been collecting CDs since March, 1983 - the year they arrived in Australia and the month of my daughter's birth. I'm experiencing ongoing problems with my expensive Densen B420-XS CD player; it stops in the middle of a track, thinks for a bit and then shuts off. This has occurred since Day 1 on newer CDs and much older ones. It is random and I'm usually stressed when I put on one - so much so that I hardly listen anymore with my hi-fi equipment. I've contacted Densen in Denmark and they've offered to pay for it to be shipped there and back for them to examine, but I hold out no hope of the problem being solved.


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## adriesba (Dec 30, 2019)

Joe B said:


> This article will give you more information on this than you really want to know:
> 
> *The Hidden Phenomenon That Could Ruin Your Old Discs*
> 
> ...


So you think this is the beginning of disc rot? Any pictures I have found online show much more extensive damage.


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## Rogerx (Apr 27, 2018)

The only thin I see on some disc's thet they become bronze color like, but they are all cheap CD'S from IMP ( that was a nicking label wayyyyyyyyyyyyyyyy back)


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## adriesba (Dec 30, 2019)

I feel like I should mention that these photos are scans. They somewhat distort the color. And these are not cheap discs. The first one is RCA, and the second one is Decca. 

I'm just not sure if I should be concerned. The pictures I've seen online of CD bronzing are much more drastic looking than these. Maybe this is the beginnings of decay, but I can't find photos of early stages of disc decay to know exactly what is going on. 

I have many discs that look like this, some more obvious than others. These two are examples of the most extreme I have seen.


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## adriesba (Dec 30, 2019)

If you can get the page to load, you can see that the people on this Blu-Ray forum don't seem to think this is a problem. The picture there looks a lot like my discs.

https://forum.blu-ray.com/showthread.php?p=17856672


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## Merl (Jul 28, 2016)

I've only had one cd that has suffered from bronzing (it was a Nimbus one). I replaced years ago (when it was reissued on Brilliant Classics). This problem is not as widespread in temperate climates I believe but I have a friend in Thailand who has had a few of these but he puts it down to the climate where he lives. I suspect he is right.


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## adriesba (Dec 30, 2019)

Merl said:


> I've only had one cd that has suffered from bronzing (it was a Nimbus one). I replaced years ago (when it was reissued on Brilliant Classics). This problem is not as widespread in temperate climates I believe but I have a friend in Thailand who has had a few of these but he puts it down to the climate where he lives. I suspect he is right.


I live in a temperate climate, but I order discs from all over the U.S.


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## apricissimus (May 15, 2013)

I don't know what they are, but I have many discs that look like this, and I don't recall ever having an issue with them not playing correctly,


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## Joe B (Aug 10, 2017)

adriesba said:


> So you think this is the beginning of disc rot? Any pictures I have found online show much more extensive damage.


As disc "rot" takes place over time, those discs *may* be at the beginning of the process.


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## Azol (Jan 25, 2015)

This is NOT disc rot, it comes from polycarbonate compound that CDs are made from, it contains impurities and sometimes these are visible, most always in a concentric or spiral pattern following the moulding process. Not a single disc displaying the pattern seen in OP failed me so far - and several of those were manufactured 20+ years ago with these patterns out-of-the-box.

This is disc bronzing: https://www.hyperion-records.co.uk/pages/bronzed.asp

So if you are worried about that particular CD, install Exact Audio Copy or fre:ac or any other CD grabber of your choice and create a flac or iso file or even burn yourself a CD-R.


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## bluto32 (Apr 25, 2015)

I too have had many CDs over the last 35 years or so that look like the photos in the first post when brand new. It isn't unusual and still happens with recent releases. My experience has been the same as Azol's: none of them have changed in appearance as far as I can tell, and I don't recall any of them failing to play or to rip properly.

I think I've had only 2 CDs that have had disc rot near the outer rim: both were pop CDs from the 80s and they looked normal when they were originally bought. (No swirling patterns like in the photos.)


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## CnC Bartok (Jun 5, 2017)

I think Azol is correct. The polycarbonate layer contains the pits, so as long as they are there, they are reflectable by the metallic layer. Tiny changes in the structure of the polycarbonate might produce lines and waves, but they do not affect the pits themselves. "Rotting" of the reflective layer will make these unreadable, not tiny variations in the plastic itself. It's done by injection moulding, so think of the layer as a supercooled crystal, you get tiny imperfections in all crystals, in reality no crystalline structure is ever perfect!

Don't fret about it!

Bronzing is another matter, and bloody annoying. My worst labels were ASV, Nimbus, and Hyperion. And yet only one CD became unplayable....


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## Art Rock (Nov 28, 2009)

Bronzing happened to me once in the nineties - in that case IIRC it was due to a wrong type of paper for the booklet that caused it. Mine was a Hyperion CD and the company replaced it immediately after I sent them the defective CD.

CD's that have become unplayable is also rare for me (collecting since 1986). Over the past few years, I've re-listened to (and cataloged) all my CD's of composers starting with A-R so far, many thousands, and found only one (Bartok's SQ's on DG) that had gone off.


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## jegreenwood (Dec 25, 2015)

I've had three discs go bad. Fortunately I was able to copy one to a CD-R (subsequently ripped) and rip another before all of my drives failed to read them. I lost one to bronzing (EMI-Reflex).


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