[WAY OFF-TOPIC] Holes in CD's

Hello,

I really wasn't sure where to go with this so I figured I'd start here. I've got a major problem. It seems several of my cd's have somehow developed microscopic holes that go through the layer of mylar(?) that contains the cd data. I have no clue how this happens but I can see through the very tiny holes when I hold the cd up to a light. This has happened to 6 or 7 of my cd's. How the heck does this happen?!?!? It's getting annoying!

Anyone else have the same probelm? Any suggestions would be appreciated...

Owen
 

UrSv

Member
2002-01-31 5:48 pm
Sweden
Holes in CDs?

I am sorry to say but I have seen that many times before. I used to work in a record store a few years back and some manufacturers or batches seemed to have that problem. In my opinion the holes in your CDs probably were there from day one but when you look at a CD with no bright light behind it (as there normally isn't) you don't see them. Holding the CD in front of bright light immediately reveils the holes however. I found CDs with just a few holes at around maybe .01 mm as well as CDs with 100 holes up to .25 mm (all numbers and sizes are rough estimates of course).

Check the CDs that you buy immediately and take them back to the shop if you find any holes is my sugeestion.

On some of my CDs there is a problem developing over time which is where the reflective layer slowly is truning red/yellow and loosing reflection.

/UrSv
 
Very small holes...

Hey all, thanks for the input.

The holes i am referring to are very small, the largest one looks to be about half a milimeter across, while the holes on the other cd's I have are less than that. The cd with the largest hole looks as if it had a very thin pin stuck through it because the plastic has been penetrated. The other cd's don't show this. They simply have holes in the reflective layer. And I know they were not there when I got the cd's because some of them I've had for a while and then all of a sudden they start to "loop" or skip a lot on a certain song. So, I pull them out and lo-and-behold, theres a hole right near where that track would be. Something else interesting is that all the cd's that this has happened to lack a label that completeley covers the top of the cd. In other words, they usually are cd's that have a little text printed on the 'non-data' side and you can see the reflective layer. maybe this has something to do with it? And often i've had these cd's for a while so I wouldn't be able to mail them back or whatever.

Any more ideas?

Thanks,

Owen
 

Jason

Powder Monkey
Paid Member
2000-10-08 1:19 pm
Melbourne
www.diyaudio.com
While we're talking about stuff way off topic and to do with holes, you might be amused to hear a story from my earlier years. Consider it garnish for the thread ;)

I was living with my parents at the time (being about 5 years old), and was perched on a seat in the living room. On my right was a small table with telephone, and a bunch of loose pencils and pens. On my left was a potential pencil holder, given a bit of DIY nouse.

I spent the next hour pushing the pencils in and out of the the pencil holder, creating an array of pencil sized holes in said device-to-be. After I had finished, I inserted the few loose pencils and pens into aforementioned holes, finishing the job. How pretty, I thought. I then ran off to find my dad and show him what amazing DIY skills I had.

My dad had been off chatting with one of his friends, "Bab", and they both returned to see what I was making such a fuss about.

To my dads absolute embarrassment and Bab's horror, I had succeeded in turning the brand new and very expensive speakers Bab had just brought over to show off, into the worlds most expensive pair of pencil holders.
 
CD flaws

Hello Jason,



nice tie you'r wearing around your neck today, Uber-Fanatic :)

call you if i need a pencil holder, custom-made models avaiable?

ROTFLMAO! :)



hello all,

CD flaws:

during uiniversity i was working student at a company developing and manufacturing online inspection systems, laser scanners, and one of them was for inspection of CDs and other optical disks. The socalled "pin holes" in the reflective layer AudioKid was embarrased by are minor flaws if their diameter stays below 2.5 mm.



Surface scratches are more serious as the act as a µ-prism defracting the laser beam. Any surface degradation in fact acts as such, giving the CDPs error correction a hard time, the more, the harder the time.



This was clearly measurable on the inspection system as well as clearly audible: Have a thin to invisible layer of grease, butter, margarine, whatever on your CDs surface and compared to an unpolluted one you'll think this is a different CD.



A real mean thing are scratchy damages on the printed side of the CD as the reflective layer is protected by the print and a very thin layer of lacquer swirled on the surface. Those damages tend to grow. the reflective layer comes off in flakes although you do not se it at first. A very recommended way to meake data CDs permanently unreadable even by data recovery professionals, we tried that out back then. one radial scratch or two over the whole radius will do fine.



The highest/nastiest grade of flaws are inclusions in the polycarbonate itself close to the reflective layer, the less close, the worse they are.

They are not necessarily visible by the bare eye and their influece always extends more into the optical material than visible due to the mechanical stress extending in proximity up to several mm.

Those inclusions cause the optical properties of the polycarbonate to change dramatically as the material experiences mechanical stress during hardening. Results are refraction index changed, polarizing plane of the laser beam changed and dichroitic effects: refraction index is differently changed depending on the polarizing plane change, double refraction occurs or is changed.



Conclusion: Don't worry, be happy if you have only some tiny pinholes. TME returning the CDs to the shop helps little as the new CD then has the pinholes just in different location.

And I do not worry if my vinyls only have some tiny pressing bubbles :)
 
Holes in CD's

Ok,

I understand that there are defects in the material used in making cd's. Wouldn't this show up before i've even played the cd once? Does this get worse/do the holes get bigger over time as i play the cd's? I just find that all the cd's that have this problem i've had for more than half a year and all of a sudden they start skipping. And I know for a fact that the holes were not there when I purchased the cd's. I can see how the label side can get scratched up as i do play my cd's (almost all of them) a lot.

Just wanted to clarify.

Thanks...

Owen
 
I'll jump in now with a couple of things. My first question, AudioKid, would be how you store the CDs, do you store them in their cases, sleeves, or what. Do you have a tendency to leave them lying around/stacked up? If so, it may simply be that you're seeing the results of the wear on the CDs. As was mentioned earlier, the reflective media itself is only protected by a very thin layer of lacquer on the label side. So its possible the CDs are just wearing out. The reason it may seem more prevalent on the CDs without complicated labels would be that those CDs have a little more protection than those without the complex labels.

Just my opinions/thoughts...
 
Re: Holes in CD's

Owen,







it well can be that the reflective layer comes off in tiny flakes and the former small pinholes get bigger with time and mechanical wear.



Probably no means against it except careful handling.



Two hints:



* Care for your CDs as if they were vinyl records, handle them by the edge only, never touch the faces, better, consider your CDs to be a camera lens' optical surface. No scratch, no etching finger print, no grease !!

* Get your CDs out of the sunlight !! particularly the self-burned ones! (yes, i mean those decentralized safety copies! :) ) . Keep them in cases not giving the UV light too much access.
 
Thanks

Thanks for the advice...

I usually do handle my cd's fairly carefully. Hardly ever touch the read surface. I keep them in their cases unless they are in my car, and then they are in one of those big cd binder things. And yes, i've seen what sun can do to a cd. Not fun! They are mostly burned cd's because I don't want to leave my rare cd's in my car. :D Luckily I haven't gotten any holes in those $60+ value cd's. Guess I've gotta go buy some new cd's... But, on the bright side, I've got some new rifle targets. :cool:

Thanks again,


Owen