Top with the Label or Bottom - Printable Version
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Top with the Label or Bottom by lrac522 on 02-09-2006 at 04:05 AM
Which side should be protected better on your CD?
RE: Top with the Label or Bottom by qgroessl on 02-09-2006 at 04:12 AM
why not both? lol.... I'm sure there's a logical reason why they have the label on the top.
RE: Top with the Label or Bottom by [MR] on 02-09-2006 at 04:14 AM
i think the bottom coz thats where all the data is. why would u care about the top?
RE: Top with the Label or Bottom by qgroessl on 02-09-2006 at 04:17 AM
Well... on PS2 disks sometimes if you get a scratch on the top you can completely screw up your game.... and the ones on the top aren't fixable... the ones on the bottom are.
RE: RE: Top with the Label or Bottom by lrac522 on 02-09-2006 at 04:19 AM
quote:Issit? Think again...
Originally posted by [MR]
i think the bottom coz thats where all the data is. why would u care about the top?
RE: Top with the Label or Bottom by [MR] on 02-09-2006 at 04:28 AM
quote:you think that messing with the label on the top would really matter when getting data on or off a cd? no.
Originally posted by lrac522
Issit? Think again...(Smilie)
RE: Top with the Label or Bottom by qgroessl on 02-09-2006 at 04:32 AM
Does it or doesn't it?.... I know a scratch on the top can ruin a CD... But I'm pretty sure there isn't data stored on top... just that the scratch would affect the deep data.
RE: Top with the Label or Bottom by WDZ on 02-09-2006 at 04:50 AM
http://www.cdrfaq.org/faq07.html#S7-12
quote:That FAQ is about CD-Rs, but I assume the same applies to all CDs...
If you scratched the top (label) side of a CD-R, and it no longer works, your disc is toast. (If you scratched it, and it still works, copy the data off while you still can.)
If you scratched the bottom side, then all you've done is etch the polycarbonate (plastic), and it can be repaired like any other CD. A common misconception is that the data is on the bottom, but if you examine it carefully you will see that the data is beneath the label. The laser reads the data through the polycarbonate layer, and if the layer is scratched the laser will refract onto the wrong part of the disc.
RE: Top with the Label or Bottom by Patchou on 02-09-2006 at 08:26 AM
Yes, it applied to all CD and DVD formats. Scratching the top of your disk makes them definitively unreadable.
RE: Top with the Label or Bottom by John Anderton on 02-09-2006 at 10:53 AM
quote:Thats what i was going to say ..... take a old cd and try to scratch off the label and silver foil ..... you will get a transparent peice of plastic which is good for no other use than playing frisbee if you live in an apartment on the 6th floor or something
Originally posted by Patchou
Yes, it applied to all CD and DVD formats. Scratching the top of your disk makes them definitively unreadable.
It has happened to me
quote:They are
Originally posted by groessl35
the ones on the bottom are.
Some of my dvd's are scratched from the bottom but the inner layer which keeps the data and the label are perfectly ok. The disc isnt always readable. How do you fix it Cause imo it cant be ....
RE: RE: Top with the Label or Bottom by CookieRevised on 02-09-2006 at 11:30 AM
quote:Sorry, but that faq contradicts itself (although it states somewhat true things (but not completely!), it states it in the wrong way or not exact enough and misconceptions may occur)...
Originally posted by WDZ
http://www.cdrfaq.org/faq07.html#S7-12
quote:That FAQ is about CD-Rs, but I assume the same applies to all CDs...
If you scratched the top (label) side of a CD-R, and it no longer works, your disc is toast. (If you scratched it, and it still works, copy the data off while you still can.)
If you scratched the bottom side, then all you've done is etch the polycarbonate (plastic), and it can be repaired like any other CD. A common misconception is that the data is on the bottom, but if you examine it carefully you will see that the data is beneath the label. The laser reads the data through the polycarbonate layer, and if the layer is scratched the laser will refract onto the wrong part of the disc.
Also, while they talk about the top part in that paragraph, the last sentence is not about the 'top' part, but about the 'bottom' part:
The laser reads the data through the polycarbonate layer (=bottom protection layer), and if the layer is scratched the laser will refract onto the wrong part of the disc.
But, it does NOT matter what side you scratch. Scratching the top side deep enough will render the disc useless as you also damage the aluminium reflection layer or even the protection/data layer which contains the physical data (pits/falls) on the disc.
Scratching the bottom side deep enough (scratching thru the polycarbonate protection layer) will do exactly the same: you will damage the pits and falls and maybe even the aluminium reflection layer. Although this polycarbonate protection layer is thicker than the top 'label' layer.
Another pointer: If you scratched the bottom side, then all you've done is etch the polycarbonate (plastic), and it can be repaired like any other CD.
This is NOT always true, only superficial scratched can be repeared, deep scratches will permanently damage any CD just as well...
----
1) sticky or printed Label (red part in the graphic)
2) Acrylic layer (top protection layer) = 200 µm (micometer)
3) Aluminium reflection layer (makes the laser bounce and detect) = 0.1 µm (micometer)
4) Polycarbonate plastic layer (bottom protection layer) = 1.2 mm or 1200 µm, this layer also contains the actuall pits and falls which represent the physical data.
So yes, the bottom layer does contain the data (although the pits and falls are much closer to the top than to the bottom).
The aluminium layer above that is only to bounce back the laser beam and does NOT contain the actuall data per-say; the physical data (pits and falls) is formed by the bottom protection layer!
pits and falls are 125 nm tick = 0.125 µm = 0.000125 mm
quote:This is not because you scracthed of the label or because "the data is beneath the label". This happened because while scratching it off, you made very deep scratches; scratching right thru the top protection layer (which is relative very thin compared to the bottom protection/data layer).
Originally posted by John Anderton
quote:Thats what i was going to say ..... take a old cd and try to scratch off the label and silver foil ..... you will get a transparent peice of plastic which is good for no other use than playing frisbee if you live in an apartment on the 6th floor or something
Originally posted by Patchou
Yes, it applied to all CD and DVD formats. Scratching the top of your disk makes them definitively unreadable.
It has happened to me
quote:How do you know this? You examined every micro-inch of the datalayer of the CD under a microscope?
Originally posted by John Anderton
Some of my dvd's are scratched from the bottom but the inner layer which keeps the data and the label are perfectly ok.
quote:You (can try to) fix it like you fix any other CD. Though it is never sure if it will repear every damage.
Originally posted by John Anderton
The disc isnt always readable. How do you fix it
RE: Top with the Label or Bottom by John Anderton on 02-09-2006 at 07:05 PM
quote:Well what actually happened was that it was a cheap disc that was lying somewhere in one corner of my room for about 2 years. Eventually when i got to it half the upper label was detatched. So i just ripped the entire thing out. Once thats gone, since there is nothing to reflect light off, i threw it. I couldnt think of anything to stick there that would be opaque and bouce of light like that
Originally posted by CookieRevised
This is not because you scracthed of the label or because "the data is beneath the label". This happened because while scratching it off, you made very deep scratches; scratching right thru the top protection layer (which is relative very thin compared to the bottom protection/data layer).
I think i did the right thing ... i dont think it could be used .... what do you think cookie ??
RE: Top with the Label or Bottom by Voldemort on 02-09-2006 at 09:11 PM
quote:
Originally posted by John Anderton
i dont think it could be used
no , it was useless
RE: Top with the Label or Bottom by [MR] on 02-09-2006 at 10:14 PM
to me it sounded like you were saying if u scratch the label that it makes the disc unreadable. but now i understand what u were trying to say.
RE: Top with the Label or Bottom by ShawnZ on 02-09-2006 at 10:26 PM
quote:
Originally posted by Patchou
Yes, it applied to all CD and DVD formats. Scratching the top of your disk makes them definitively unreadable.
Not quite. CDs have the layer at the top, but DVDs have them dead center. You'll still harm it, but its not right below the label.
RE: RE: Top with the Label or Bottom by CookieRevised on 02-10-2006 at 12:52 AM
quote:tbh, that doesn't make sense if you don't specify about what layers you talk about...
Originally posted by ShawnZ
quote:Not quite. CDs have the layer at the top, but DVDs have them dead center. You'll still harm it, but its not right below the layer.
Originally posted by Patchou
Yes, it applied to all CD and DVD formats. Scratching the top of your disk makes them definitively unreadable.
eg:
- "CDs have the layer at the top": What layer?
- "its not right below the layer.": What isn't below what layer?
Furthermore, I don't know what you're talking about with DVD's have them dead center. The only thing they have "dead center" is an adhesive layer which holds both sides together..
The difference that DVD's with double layers have is that they contain an extra semi-transparant/reflecting coating layer between the metal layer and the polycarbonate "data" layer. Single sided DVD's are exactly the same as CDROM's (thus appart from the adhesive middle layer). And depending on the format "single sided" or "double sided", this pancake is repeated for both sides or not.
All in all, DVD's are build up (almost) exactly the same as CDROM's. So I don't know what you're on about here....
RE: Top with the Label or Bottom by Purity on 02-10-2006 at 01:11 AM
Haha, I knew it, kinda figured it out myself, taking off the foily data
thinger...
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