CD reflective layer quality in regards to performance

Hi,

I have some CDs, both brand new and used spanning many years that when looking at the playing surface side of the disc it looks like there are swirls, feather like patterns and blotches instead of a nice completely smooth surface for the aluminum reflective layer. It still reflects properly under light despite this. It just looks weird. Is this due to the sputtering of the aluminum not being spread evenly or is this a problem with the substrate? Or are both the aluminum reflective layer sputtering and substrate to blame? Note, this is different from CD rot that has been discussed here in the past as there is no bronzing on these CDs like those that I have on my old UK PDO discs which still play fine. Does this uneven look in the reflective side of the CD with these uneven coats of aluminum have any effect on the laser pickup, sound quality or other degrading issues in performance? Has anyone else that has CDs like this with an uneven coat of aluminum had any performance issues with their discs? I have not heard anything abnormal when playing these CDs myself. But one has to wonder if there is an effect on the playback of a disc like this compared to a normal looking one. Gold CDs seem to bypass this issue so we don't need to discuss them unless things have changed with their gold reflective layer quality. Also, if anyone does have CDs with these cosmetic anomalies on the playing side, is there problems with ripping these CDs or when you test them with EAC or other software do you get any CRC or BLER errors? I'm guessing these anomalies are due to quality control issues in the manufacturing of CDs. But does it really cause any problems? Is anyone concerned about this?

I'm just curious about this and wonder what others here have to say about it if they have encountered any CDs like this.

 

I have several CDs like this. Some of these I have had for 20 plus years. One of them is Prince's Diamonds and Pearls. These CDs play fine. There is no rot or any other type of physical defect. I have never had any problems ripping the CDs, testing the CDs on various software. I will take a photo and upload it onto here as soon as I open up a Photo bucket account since we have to have one now in order to up load pictures. (I'm not complaining Gourts, just stating a fact.)

P.S. I have emailed several CD companies asking about the various patterns and the response I always get is "we'll have our techs research this matter and contact you later." To which they never do.

 

Consider using imgur.com for uploading pictures. Don't need an account and you can have a link to share in seconds.

Disclaimer: don't work for imgur, just think it's a useful and user friendly photo sharing tool.

 

Thanks, for the heads up.

 

bump

 

I've had this a few times, but can't remember which CDs. But I do know that after all these years it was never a problem.

 

I have a few CDs bought new/sealed and used that have these cosmetic abnormalities in the reflective layer. Stuff bought recently as well as those from years/decades past. Some sources on the internet say that this can be a problem with laser pickup and cause degraded sound quality due to laser reflectivity problems. I know some info on the web is misleading and there is a good amount misinformation out there.

Does anyone have first hand experience working at a CD pressing plant that knows the real deal about this? Has anyone done any tests between a normal looking CD and one with these reflective layer abnormalities to find out if there is any differences in the playback quality or error rates?

 

Has anyone done any tests between a normal looking CD and one with these reflective layer abnormalities to find out if there is any differences in the playback quality or error rates?

I have done both the CDs sound the same with no errors. Like I stated earlier, I have CDs that I've had for over 20 years with this abnormality that I've brought brand new. Everything is fine with them. I also have several DVDs like this that play fine with no errors.

 

Thanks for the info.

 

Older CDs also has a thicker layer, now you can see through the metal.

Do you think it has something to do with cost cutting?

 

I think it's the lacquer rather than the actual aluminum layer, which is incredibly thin. I did have one disc with what looks like a nasty scratched surface, but plays fine; that may be an uneven aluminum layer.

 

I'm guessing a bad quality substrate is not the cause of this since the information bits are stamped onto the top of the substrate. If there was damage to the substrate during the molding/stamping process this would render the CD unplayable even if the reflective layer was intact and normal looking.

I'm assuming if the reflective layer is uneven with weird patterns, it probably makes no difference as long as the entire surface is covered with aluminum (smooth or not) since it still retains a mirror image for the reflective laser pickup.

Since everyone here that has posted about their CDs playing and ripping OK without errors despite having this cosmetic defect to the reflective layer. Than this urban legend of internet misinformation can be put to rest.

 

Very well put.

 

Below is an example of 'swirling'. This is disc2 from a 5-cd boxset from 1996 that I purchased new. The music plays all 31 tracks fine, however it shows only 'Track 1' when you put it in a cd player. You can't skip to a specific track, if you want to hear track 6 you have hold down on 'search' til you get there. You can't program a track. The other discs play and track normally (and have none of the 'swirling'). Is the error from the 'swirling' manufacturing defect? Subcode Channel P or Q error? Both? I don't know.

 

It sounds like an indexing error. My Wall Flowers CD Bringing Down The Horse shows it only having 3 tracks yet all the tracks play fine. I have to manually fast forward to anything passed track 3. This CD doesn't have any patterns on the smooth side. I was gonna take it back but the store I bought it from was sold out. This was in 1996.

 

Wow, that's weird. I don't know what to make of that. Roger Meadows is most likely correct about it being an indexing problem rather than a laser pickup issue. I would think that if there was a problem due to reflectivity, it would affect the whole CD. Perhaps someone else here has this same box set and may have received a bad disc 2.

 

A few things:

1. The disc shown was pressed that way. i.e. the Table of Contents data is what shows up on the CD player display. They made it with one track and no track indexes. Pretty annoying, but that how it was done. if was defective, it would not even initialize.
2. Do not confuse visible appearance with laser readability. the swirl optical waves in the plastic and varied metalization are not really a big deal. They are just artifacts of the mould or sputtering. The wavelength's reflectivity of the pits is what matters. Visible light is different than laser light. Some CD plants have near transparent metalization when held up to a light, but have low BLERs because it is reflecting well to the laser at the laser's wavelength.

Some companies have done sloppy metalizing near the edges and it looks crappy, but sputtered well where the data is. Do not worry about.

3. Pinholes (particularly in early 80s discs) are a result of a contaminant or missputter at that spot, however, it is often coated there but not visible. i.e. there's usually plenty of non visible material to reflect.

These aren't LPs, where physical pressing defects create sound artifacts most of the time.

 

Swirling is actually caused by staining on the stamper. When the stamper is created, the electroplating process can create stains on the stamper where chemical residue is not completely removed. The image of the stains is carried through the injection molding of the final CD (or DVD or Bluray). While the reflectivity is technically altered due to the stain, its effect is heavily scrambled throughout the playback of the disc by the interleaving of the data. Usually staining will not generate uncorrectable errors. Error correction is always our friend.

The choice for a disc manufacturer to implement stained stampers in manufacturing is strictly a financial one. Since electrical errors are rarely generated by stamper stains, manufacturing costs are reduced by not recreating stampers without stains. The only drawback in this case is the cosmetic appearance of the play side of the disc. It doesn't look as pretty to the eye.

Extreme cases could cause electrical errors, but most manufacturers should be able to flag such a situation. Recent quality control, however, seems to allow for any degradation of the manufacturing process to be shipped out of the factory.

 

I had a treasured indie CD from the early 90s (TwinTone label) which lost a few chunks of it's reflective layer (even with careful use). Those tracks (from inside to out) either skipped or would hang the player.

 

Thanks for all the valuable info. So I don't need to worry about these reflective layer swirls/anomalies on my CDs as they are only a cosmetic defect/nuisance and don't affect the playback quality of the CD itself?

 

Thank you for the very informative info as well. What are electrical errors? Do I really need to be worrying about this reflective layer swirling at all? Should I avoid buying used CDs with these anomalies?

 

Sorry to hear about your disc going bad. I've had the same thing happen to a couple of my CDs I bought used. The top lacquer layer and reflective layer peeled off when I was cleaning one of them. It was a Nimbus pressed CD.

http://www.discogs.com/Chesterfield-Kings-Night-Of-The-Living-Eyes/release/2616035

 

I've got quite a few CDs with blotches or swirls like that from the '90s and forward. Can't remember any CD from the first Polygram factory to have any such visual defects (they had pinholes instead). However, all rips perfectly in EAC, with no need to reread any areas. The latest really blotchy one was the deluxe version of "Tapestry" and disc 1 had such a large blob I thought it was ruined. But, as usual, still reads without problem. It only seems to be a visual and not data destroying problem.

 

Something similar happened to my copy of Peter Gabriels "So", manufactured by Nimbus. However, the top layer was separate to the reflective layer and once I stopped cleaning och took away any loose bits, the record seemed fine. Must've been the usual acrylic coating under the sticky label coating. I put a CD sticker on (those that covers the whole disc), and the CD is still fine some 10 years later.

 

I have a copy of Yes's 90125 that has some small swirls near the edge of the disc (7567 90125-2 2893 354 02 matrix, hand etched initials; late '84 perhaps). I think there are other ones as well. Not common, but they happen.