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I have old CDs/DVDs which have some backups, these backups have some work and personal files. I always had problems when I needed to physically destroy them to make sure no one will reuse them.

Breaking them is dangerous, pieces could fly fast and may cause harm. Scratching them badly is what I always do but it takes long time and I managed to read some of the data in the scratched CDs/DVDs.

What's the way to physically destroy a CD/DVD safely?

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10 Answers 10

up vote 70 down vote accepted

The proper way is to get yourself a shredder that also handles cds - look online for cd shredders. This is the right option if you end up doing this routinely.

I don't do this very often - For small scale destruction I favour a pair of tin snips - they have enough force to cut through a cd, yet are blunt enough to cause small cracks along the sheer line. Kitchen shears with one serrated side work well too. You want to damage the data layer along with shearing along the plastic, and these work magnificently. Do it in a bag, cause this generates sparkly bits.

enter image description here

There's also the fun, and probably dangerous way - find yourself an old microwave, and microwave them. I would suggest doing this in a well ventilated area of course, and not using your mother's good microwave. There's a lot of videos of this on YouTube - such as this (who's done this in a kitchen... and using his mom's microwave). This results in a very much destroyed cd in every respect. If I was an evil hacker mastermind, this is what I'd do. The other options are better for the rest of us.

enter image description here

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While the microwave option would work, I'd recommend against it :) +1 –  Colyn1337 Oct 15 '13 at 15:02
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I'd just note that shredders may not always do a particularly complete job. My shredder has a CD slot, and it just cuts two parallel lines, making three approximately equal thirds. If someone were really determined they could presumably recover some data from those pieces. –  Bob Oct 15 '13 at 15:14
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Put the CD/DVD on a mug of water - gives the µwave something to heat, less likely to burn it out, you still get pretty sparks and arcs. –  Ecnerwal Oct 15 '13 at 15:28
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For the shredder option you do need cross cut as a minimum, but it depends on what level of effort you believe a would-be attacker is able to bring to bear on reconstructing the data. –  James Snell Oct 15 '13 at 19:51
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If you use a microwave, I wouldn't eat food cooked in it afterwards. <_< –  AlbeyAmakiir Oct 15 '13 at 21:36

This website explains 10 creative ways of doing this:

  1. Wraps the discs with food wrap then fold it.

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  2. Shred the discs. There are several CD shredder machines, that operate like common paper shredders.

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  3. Cut the discs. If you don't use a shredder, a heavy pair of scissors can easily cut through a disc. The reflective foil will crack and flake, which can be messy. Be careful, as cutting the disc is tough. If you prefer a clean and safer alternative.

    enter image description here

  4. Break the discs. Wrap the disc in a towel and then break or crack it with a firm kick or heavy hammer. The towel will protect you as CDs tend to shatter into pieces. Dispose of them while wearing safety gloves.

    enter image description here

  5. Microwave the discs. Place the disc into a microwave and set it for 5 seconds, or until you see sparks along the surface of the disk. When you pull it out, it will have a spiderweb pattern of cracks. However, this can be dangerous and destroy your microwave, so it is not recommended.

    enter image description here

  6. Use duct tape to remove the foil lining from the discs. Put several strips of duct tape over the top of the CD. Once the tape is firmly attached, rip it off. The foil lining should come off and you will be left with a transparent CD. This trick works on some CD's only.

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  7. Cut the discs with a knife. Some CDs, especially burned ones, have the data layer unprotected by plastic. In this case, take a table knife to the label and start scraping shiny flakes in the trash.

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  8. Sand the discs. Use a belt sander on the label side. This is quite messy, so do it in an area that is easy to clean.

    enter image description here

  9. Center punch the discs. Using a self-firing center punch or a hammer and a manual punch, strike a couple of dozen deep dimples into the shiny side of the CD or DVD. Anything less than a dozen strikes could allow data to still be extracted.

    enter image description here

  10. Erase the discs with the computer. If you have a DVD or CD drive on your computer, you can erase the data on the disc, which only works on burned, rewritable discs.

    enter image description here

From these 10 ways, I've have chosen my preferred method - this is in bold text, but take it easy, you could break your microwave by doing this(and this could be dangerous for your microwave and for you).

Choose one or more, or even all the 10 ways if you really want to make sure no leak of information could be retrieved from any piece of the disposed CD's foil lining, but I can assure you any of these methods will do the job.

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2  
The microwave method is actually not so much dangerous as it is unpleasant. The smell of overcooked cd will haunt your kitchen for days. –  Marcks Thomas Oct 15 '13 at 21:35
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The method #9 seems to be unsafe since the center part is rather untouched. –  magu_ Oct 16 '13 at 9:29
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#10 you will need to overwrite many times to do this properly. –  tryingToGetProgrammingStraight Oct 16 '13 at 10:57
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How does the plastic wrap one work? –  AJMansfield Oct 16 '13 at 23:24
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The plastic wrap is to contain the flakes you'd get when you fold the cd in 2. It just keeps the psudo-glitter from getting everywhere like it tends to do. –  Journeyman Geek Oct 16 '13 at 23:44

The answer by Journeyman Geek is good enough for almost everything. But oddly, that common phrase "Good enough for government work" does not apply - depending on which part of the government.

It is technically possible to recover data from shredded/broken/etc CDs and DVDs. If you have a microscope handy, put the disc in it and you can see the pits. The disc can be reassembled and the data can be reconstructed — minus the data that was physically destroyed.

So why not just pulverize the disc into dust? Or burn it to a crisp? While technically, that would completely eliminate the data, it leaves no record of the disc having existed. And in some places, like DoD and other secure facilities, the data needs to be destroyed, but the disc needs to exist. If there is a security audit, the disc can be pulled to show it has been destroyed.

So how can a disc exist, yet be destroyed? Well, the most common method is grinding the disc down to destroy the data, yet keep the label surface of the disc intact. Basically, it’s no different than using sandpaper on the writable side, till the data is gone.

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The problem with this is that the data is on the same side of the plastic layer as the label. If you grind it down until the data is gone, what's left will crumble in to dust. If you just scratch up the bottom surface with sandpaper, the damage can easily be filled and polished out. –  ali1234 Oct 15 '13 at 15:37
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the data is beneath the label side, and as such grinding that side makes more sense to me. I was avoiding exotic solutions, otherwise, maybe dumping it in a suitable solvent might work. Someone on chat was jokingly suggesting thermite as well. –  Journeyman Geek Oct 15 '13 at 15:39
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i dont think thermite falls into the "safe" category. But it does faill into the "fun" category. –  Keltari Oct 15 '13 at 15:48
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The DOD approved CD grinder where I'm employed works on the label side, and AIUI destroys the reflective layer leaving a bare plastic disk. Adhesive labels need to be soaked off before it can be used. DVD capable models were much more expensive because the data's stored in the middle, so we don't have one that can do them. –  Dan Neely Oct 15 '13 at 19:18
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youtube.com/watch?feature=player_detailpage&v=5kdMItKb25s I guess you could blend it. –  Journeyman Geek Oct 16 '13 at 5:43

I typically put my old CDROMs in a plastic bag and use oven mits to bend them. This protects my hands from shards and protects the surroundings from flying projectile shards.

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Yep, if you bend it enough (trying to fold it in half), it'll shatter into many many pieces. –  Jon Oct 16 '13 at 15:33

A good standard for media sanitization & destruction methods used to be the NISPOM/DoD 5220-M/DSS Clearing & Sanitization Matrix documents. Finding current versions of these online seems to be tricky - it appears they have been removed from public viewing, at least on first-party websites. However, as the basic principles of optical media haven't really changed much recently, I think the following snippets from a 2007 version of the DSS C&SM might be of interest:

  • Incineration is the most common and recommended method for removing recording surfaces.
  • Applying an abrasive substance to completely remove the recording surface ... Make certain that the entire recording surface has been thoroughly destroyed before disposal. Ensure proper protection from inhaling the abraded dust.
  • Smelting, disintegrating, or pulverizing...
  • Destroying by the use of chemicals ... Chemical destruction is hazardous and should only be done by trained personnel in a proper environment.

The more current and publicly-viewable NIST SP 800-88 has this to say for destruction methods of optical media:

Destroy in order of recommendations:

  1. Removing the information-bearing layers of CD media using a commercial optical disk grinding device. Note that this applies only to CD and not to DVD or BD media.
  2. Incinerate optical disk media (reduce to ash) using a licensed facility.
  3. Use optical disk media shredders or disintegrator devices to reduce to particles that have a nominal edge dimensions of point five millimeters (.5 mm) and surface area of point two five square millimeters (.25 mm2) or smaller.

For that last option, it looks like this should do the trick:

http://youtu.be/0yNAbHKF8pY

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+1 The tip on the quoted "applies only to CD and not to DVD / BD" is important: media that have more than one layer (as DVD and BD) might retain lots of data it you don't grind all the layers. –  woliveirajr Oct 16 '13 at 20:49
    
And here I was thinking the best way would be to take it into my lab at work and soak it in some organic solvent. I figure if it is a blob rather then a disk it should be fine, or better still totally dissolved. –  Canageek Oct 17 '13 at 23:24

I would go with a CD destroyer that does not cut the CD/DVD into several pieces. Cutting a CD into several pieces always leaves sharp edges and tiny metal or plastic particles flying around.

I'm very happy with my Olympia 100DX cd destroyer. (I'm sure there are similar models from other makers!) It destroys the CD/DVD by running it through two metal cylinders with tiny spikes on them.

  • It's very fast (30 CDs per minute),
  • doesn't leave a mess (CDs look like before, just with hundreds of tiny impregnations),
  • if you want to be extra-secure, you can run each CD through it multiple times.

enter image description here

One pass:

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Three passes:

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Although not practical for everyone, here's another way that doesn't leave much of a trace. It should be impossible to recover the data considering it has been vaporized.

Positioned between two high-voltage transformers, the spinning CD has its data violently stripped off in just a matter of seconds. To be fair, the data isn't erased per se, but the metallic substrate on which the data is recorded is flaked off by the aggressive application of electricity.[2]

high voltage

[video]

There is also a DIY at home technique that works on the same principle but isn't as spectacular. http://www.instructables.com/id/How-to-destroy-a-Justin-Bieber-CD/

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1  
Bonus points for mentioning Photonicinduction, but I think this may be a bad answer, and no, not because it's silly and impractical for most people. It's entirely possible that this method does little to destroy the actual grooves in the polycarbonate that hold the information, and that the disc could be remetallized using the same technique as used in manufacturing. –  nitro2k01 Oct 19 '13 at 7:06
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@nitro2k01 OP mentions discs that have backups, which implies that they were blank first, so your point about grooves in the poly-carbonate doesn't apply (or does it?). Correct me if I'm wrong. (grooves in the poly-carbonate will exist only when they are factory-produced, right? A CD/DVD writer will only change the color of the photosensitive dye / crystallize metallic alloy) –  kedar Oct 19 '13 at 11:24

You could always put a cloth over the CD and iron the hell out of it. Pretty effective.

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What setting? and when is the cd properly ironed - it has no wrinkles? –  Journeyman Geek Oct 17 '13 at 7:50
    
@JourneymanGeek: Cotton or higher. Just place the iron on it for about 30 secs... just enough to melt the top layer so that the laser cannot read it properly. It will look, how do you say, smudged? once its done. –  Bobby Alexander Oct 18 '13 at 5:57

Get a metallic can, put some combustible on it, throw the cd / dvd on the top, set fire.

Not very ecological as plastic might release some toxic smoke.

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I've always been a fan of the power drill approach. http://www.youtube.com/watch?v=wFoG_whlwIs

Personally, I don't drop scissors on them like the video, I let them spin up fast, and then send them head off down the driveway into the garage wall. It's truly spectacular.

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Looks fun, with the slight chance of deadly plastic shrapnel. Its all fun and games, until someone gets decapitated with a cd. –  Journeyman Geek Oct 16 '13 at 23:42

protected by nhinkle Oct 16 '13 at 3:18

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