Can a CD be wiped out like a floppy?

[Jinx]

I was wondering if a CD is just as vulnerable to magnetic fields as a floppy is? On floppies and tapes, the data is stored by the use of electromagnetic properties aligning the medium in a certain fashion so when replayed, it will reproduce the source…in a nutshell.

But, being that the info is burned onto a CD, can it still be wiped out by pasing through a magnetic field?

• Jinx

[friedo]

CDs are plastic. They are read by lasers. Magnets are not involved, except perhaps in the littls motors that make them spin.

So no, a magnetic field will not harm a CD.

[SlickRoenick]

No b/c compact discs (all optical media) are not magnetic in any way - just plastic.

[CC]

CD’s information storage is analagous to records. Ever hear of them? CD’s are made of areas of pits burned into the surface, much like the grooves in a record. Not magnetically stored info.

[deadeyesdad]

Magnet no. Hammer, drill, grinder, shredder, foot, tire yes.

[rjung]

Fastest and easiest way to destroy a CD is four seconds in a microwave on “high.”

Do it in a well-ventilated area, though.

[Biffy_the_Elephant_Shrew]

1. The functional part of the CD is non-magnetic, but CDs may be labelled with inks containing ferrous materials, which can conceivably cause read errors if magnetized–at least that’s what the folks who will try to sell you disc demagnetizers claim!

2. Related issue: CD-Rs can be rendered unreadable by excessive exposure to light.

[Ethilrist]

@rjung

Fastest and easiest way to destroy a CD is four seconds in a microwave on “high.”

Do it in a well-ventilated area, though.

Nah. Spray paint.

[AndrewL]

@Biffy the Elephant Shrew

1. The functional part of the CD is non-magnetic, but CDs may be labelled with inks containing ferrous materials, which can conceivably cause read errors if magnetized–at least that’s what the folks who will try to sell you disc demagnetizers claim!

CDs are ready by laser beams, which are unaffected by magnetic fields. The people selling CD demagnetizers are scam artists without exception.

[Biffy_the_Elephant_Shrew]

@AndrewL

CDs are ready by laser beams, which are unaffected by magnetic fields. The people selling CD demagnetizers are scam artists without exception.

Aw, c’mon–next you’ll be telling me that the green Sharpie trick doesn’t improve the sound!

[jayjay]

CD’s need to be physically made unreadable, either by devices that imprint a repeating pattern on the read surface or by grinding/shredding.

[Hail_Ants]

Quote:
Originally Posted by rjung
Fastest and easiest way to destroy a CD is four seconds in a microwave on “high.”

Do it in a well-ventilated area, though.

Nah. Spray paint

Heck, snapping them in half is about the quickest way. Though its surprisingly dangerous (they break rather violently and send razor sharp shards everywhere!)

[Valgard]

CD-R and CD-RW discs are written to using magnets but the recording layer has to be heated first by the laser to make them sensitive enough (the intensity of the beam is much lower when it’s in “read” mode) so unless you’re keeping the discs pretty hot a magnetic field shouldn’t cause you any problems.

I suppose a field intense enough to affect a CD-R/RW disc just sitting there would also be enough to cause other problems with your PC, like affecting your hard drive.

As far as “erasing” a CD, the data layer is directly underneath the label - from the bottom up you have clear plastic (the CD), then a thin coating of aluminum (the data layer) and then whatever label the manufacturer has painted directly on top of the aluminum. So if you want to damage a CD you don’t have to break it, microwave it or take a shotgun to it, just grab some sandpaper or a razor and scratch up the LABEL side. Try it on an old CD, then flip it over so you are looking up through the bottom plastic and you’ll see that the reflective surface is hosed.

[Q.E.D]

@Valgard

CD-R and CD-RW discs are written to using magnets…

No, they are not. Here is an in-depth article on the subject of CD-R and CD-RW technology. From this article:

Instead of mechanically pressing a CD with indentations, a CD-R writes data to a disc by using it’s laser to physically burn pits into the organic dye. When heated beyond a critical temperature, the area “burned” becomes opaque (or absorptive) through a chemical reaction to the heat and subsequently reflects less light than areas that have not been heated by the laser. This system is designed to mimic the way light reflects cleanly off a “land” on a normal CD, but is scattered by a “pit”, so a CD-R disc’s data is represented by burned and non-burned areas, in a similar manner to how data on a normal CD is represented by its pits and lands. Consequently, a CD-R disc can generally be used in a normal CD player as if it were a normal CD.

And

However, the technology used in CD-Rewritable does not incorporate any magnetic field like the phase-change technology used with MO technology. The media themselves are generally distinguishable from CD-R discs by their metallic grey colour and have the same basic structure as a CD-R disc but with significant detail differences. A CD-RW disc’s phase-change medium consists of a polycarbonate substrate, moulded with a spiral groove for servo guidance, absolute time information and other data, on to which a stack (usually five layers) is deposited.

You may be confusing CD-R(W) with ZIP disk technology, which was a magneto-optical format.