What's the best way to destroy CDs?
November 27, 2006 5:48 AM   Subscribe

What's the best way to destroy CDs?

This question has been asked before (sort of), but I'm looking for a good, easy way to destroy CDs - on a once-in-a-while basis, not on an industrial scale, like the previous question. Basically, I want to get rid of old backup CDs but I want to be sure that the data on them cannot be accessed. At the moment, I put them in a bag and hit them with a hammer a few times, to break chunks off them. Is there an easier way?
posted by Grinder to Computers & Internet (29 answers total) 4 users marked this as a favorite
Scratch them several times in lines that run from the centre to the outside edge? Perhaps use something like a compass...
posted by samstarling at 5:53 AM on November 27, 2006

Google "CD microwave".
posted by Dr.Pill at 5:54 AM on November 27, 2006

posted by medium format at 6:01 AM on November 27, 2006

Microwave them.
posted by Blazecock Pileon at 6:16 AM on November 27, 2006

Take it outside, put it data-side down on some concrete, and have at it with your foot. Or use a belt sander. Then, for good measure, turn it over and give it a couple of good, deep scratches from one edge to another passing as closely to the blank center as possible (expensive cd destroyers use this technique). Putting it in a microwave works—and quickly too—but may damage your microwave. I always thought that removing the reflective top/middle layers completely ruins a disc, but apparently it leaves the data intact, only unreadable. However if you're unsatisfied after scratching it up but good, take a strip of duct tape and affix it to the top side of the disc. When you pull it off it should take much of the reflective layer with it.

Info gleaned googling "destroy compact disc".
posted by carsonb at 6:21 AM on November 27, 2006

I just use a shredder. Anything that can handle CDs will also eat stacks of paper (12 sheets or so at a time) which is also handy. Spend a little extra for a crosscut shredder; if you go cheap you'll just end up replacing it every year or so anyway, so save yourself the trouble by getting a better one the first time. You'll find it quite handy for removing unwanted junk mail and personal papers as well. Once you send a disc through the thing, there's no way anyone will recover anything useful from it.
posted by caution live frogs at 6:33 AM on November 27, 2006

Regarding "may damage your microwave":

This is similar to the caution against running a microwave empty - the CD just won't absorb enough of the microwave energy and
it will feed back into the magnetron and damage it.


If you put a glass of water in the microwave along with the CD, the water will absorb the microwave energy (just as it does when boiling water for tea) protecting the magnetron, and the CD will fry nicely.
posted by Crosius at 6:35 AM on November 27, 2006

I second the shredder suggestion. It's cheap and fun to do.

To those suggesting microwaving: Have you actually done this yourself? It makes the entire house smell like total ass. Why on earth would you want to subject yourself to that noxious burnt plastic smell?
posted by Rhomboid at 6:47 AM on November 27, 2006

Yes, I have done it. In the garage. With the door open. I pity the fool who does it in the house.
posted by Kirth Gerson at 6:57 AM on November 27, 2006

CD/DVD Shredders
posted by blue_beetle at 6:57 AM on November 27, 2006

Microwaving seems to work but is not recommended by many of the articles that I've seen; "How to Destroy a CD-R", for example:
However, this method is not recommended for the general public, because it may damage the microwave, and it is unknown whether the byproducts of the meltdown may remain in the oven and subsequently contaminate any food cooked in it.
Overall it doesn't seem worth it (though snapping and scratching discs could also potentially be dangerous due to shards and fine particular matter).

Thanks, medium format and blue_beetle, for the links—I've wondered about this but hadn't previously seen fairly inexpensive devices for average users.
posted by yz at 7:00 AM on November 27, 2006

You don't even need a special shredder. Just walk into any Staples of Office Depot store and I guarantee that they will have a regular demo shredder sitting there with a stack of paper and a stack of old CDs that you can feed it. It seems to be a standard feature now.
posted by Rhomboid at 7:09 AM on November 27, 2006

You can cut them up with metal shears or wire cutters or even good scissors that you might already have.
posted by pracowity at 7:13 AM on November 27, 2006

Take a chef's blowtorch to them. Burn all the silver off.
posted by popcassady at 7:29 AM on November 27, 2006

The data layer is on top and so ridiculously thin (arguably a liability and a rip off on some of the cheaper varieties) you can peel it off in flakes with virtually any kind of knife, sandpaper, file, wire brush, ice pick, or the edge of concrete step. I think enough damage can be done by scraping random sections of the data layer to make it sufficiently secure for most purposes. It's not as convenient as a shredder, but with some improvisation, probably free.

DVDs are another story. The data layer is sandwiched between two layers of, as I recall, polycarbonate; which is much more flexible and obviously protects the reflective/dye area much better.
posted by evil holiday magic at 7:40 AM on November 27, 2006

BUT! If you have a microwave oven to spare and a backyard where you can spare it without filling you house with toxic smoke, the backed CD method seems funnier. Just remember to destroy the oven afterwards (which may also issue more fun) in order to avoid poisoning some innocent user down the line (anyone who might find your functioning oven in the garbage or in your backyard and put it to regular use again).
posted by nkyad at 7:55 AM on November 27, 2006

I used to have to destroy cds as part of my job and always found that the microwave got the job done definitively in a matter of seconds and never damaged the microwave. I did notice the unpleasant burnt plastic smell afterward, but that's to be expected. I'm no doctor but I'm pretty sure there's nothing that spectacularly poisonous in CDs. The only place I've seen real critical pieces about this technique is on websites selling CD shredders.
posted by UESMark at 8:35 AM on November 27, 2006

I wrap the CD in a cloth and fold it in half. It usually shatters quite satisfactorily, and you can shake the plastic slivers out into the trash. When you bend it, do so by holding it between your fingers and palm and make sure it bends outwards, away from your palm. Caveat : the shards produced are fairly sharp, and although I have never cut myself the risk is there. I went through about 50 CDs this way, and once you get the rhythm you can do one every five or ten seconds. The bang it makes as the plastic goes from elastic to plastic is also quite satisfactory.
posted by ny_scotsman at 8:50 AM on November 27, 2006

Just hold it over a trash can and fold it in half. If you want to get creative, whip out a shotgun and use them as pigeons.
posted by fvox13 at 9:09 AM on November 27, 2006

I usually just burn part of the underside with a lighter until it's warped.
posted by Captaintripps at 9:36 AM on November 27, 2006

I have a paper and CD shredder, but it doesn't shred the CDs -- CDs go in a separate slot and they basically get sanded. They end up in the basket whole but unreadable.

(Just thought I'd add that data point before you throw a CD into the blades of a regular paper shredder.)
posted by mendel at 10:25 AM on November 27, 2006

Just douse the damn thing in lighter fluid and torch it. If the fire dept shows up, play dumb.
posted by IronLizard at 10:41 AM on November 27, 2006

If it's a CD-R, the data layer is actually on top, not on bottom. It's just a thin layer of foil. Take a box cutter or pair of scissors and just scrap a few lines on the top. The foil will just flake and tear off.

I think DVD-Rs are tougher though.
posted by chairface at 10:42 AM on November 27, 2006

How long do you people leave your CDs in the microwave? Five seconds is all it takes (there's a "pop"). Add the glass of water, a la Crosius, and no damage to the microwave, no smell, just utterly unreadable data.
posted by ontic at 11:09 AM on November 27, 2006

It depends how sure you'd like to be that the data is unrecoverable. If you simply break a CD into a small number of pieces (say, 90% of the CD is in 5-10 of the pieces then most of the data sites are intact and could be recovered by advanced techniques (such as a laser that scans by moving in two dimensions over the broken pieces)

The same goes for methods that destroy just the top or bottom of the media (I suspect that microwaving fits into this category, destroying only top foil). The data on a CD-R is not stored in the top reflective layer or in the bottom polycabonate layer -- it's stored in a layer between. (see the CD-recordable FAQ). There is a diagram of the layers (not to scale) here.

CD-Rs and CD-RWs are written by heating small areas on the disc to change their optical characteristics. this page gives some temperature figures for CD-RW media -- a "blanking" pass heats the material to something like 200C.

Thus, cooking CD-RW media in your oven at 400F will have the effect of destroying all the data, though other layers of the CD-RW media might melt or release nasty chemicals when heated to this temperature, so I don't recommend doing it. I didn't immediately find a temperature figure for CD-R media, but there's a similar heating temperature that will turn all the dye to the "written" state, destroying its information.
posted by jepler at 11:41 AM on November 27, 2006

You want to damage the non-data side first. The film comes off easy. Then damage the data side/microwave/shred/scratch/whatever. No one is going to be able to read those.
posted by damn dirty ape at 2:17 PM on November 27, 2006

Drop 'em in the toaster for a few. They wither. Watch carefully to be sure they don't ignite or something stupid.
posted by Goofyy at 2:03 AM on November 28, 2006

I find that just put them in my car for a while with all my music cd(s) will destroy them. It seems to me somehow music cd(s) get destroyed all by themselves. I would say that sandpaper would work fine or perhaps finger nail polish remover?
posted by scooters.toad at 4:30 AM on November 28, 2006

You can use cap'n trips' method without a lighter if you have a hairdryer. Once there's a good warp in it you don't even need to bend it - it's useless for all but big-money recovery techniques.
posted by phearlez at 2:08 PM on November 28, 2006

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