Can I repair a scratched CD with sandpaper?

April 20, 2004 8:59 AM

Unorthodox CD scratch repair. 600 wet/dry sandpaper. Has anyone out there had success with this or other bizarre and aggressive methods? ( more inside )
posted by troutfishing to (13 comments total)

Not that I've tried, but I should think some polishing compound would work better than sandpaper.

And as mentioned in a thread about plexiglass (car dash), there are specialized plastic-polishing kits. They work like a charm on plexi, so I imagine they'd be fine with a CD.
posted by five fresh fish at 9:18 AM on April 20, 2004

Repair the top side where the label is,; gluing foil over scratches. Also you can try cleaning the cds with furniture polish with Pledge. Notice the better the cd player the better they'll read a scratch cd.
posted by thomcatspike at 9:23 AM on April 20, 2004

One of my OS install CD's got badly scratched, while I was loading my new OS, when I bumped my computer tower - jarring a CD reader with a CD inside spinning 52k can be bad news. From the sound of it, I thought the CD had broke into a thousand pieces ; when I removed it from the CD tray it was in one piece but with some deep concentric scratches.

But my CD then wouldn't install the OS - it would out halfway through the process with a "reading error" message. So I tried a Memorex $10 "scratch repair" system which came with a little bottle of aluminum oxide polishing compound. I threw the cheap Memorex plastic CD polishing gadget mechanism away and resorted to polishing by hand with the polishing compound and a lens cloth - this worked far better than the plastic gadget had.

I polished and polished and polished some more, until my fingers fell off and my arms turned into gnarled stumps. to no avail. I accomplished a mirrorlike sheen, like new, on my precious CD disc, but the grooves in the CD were still there and the CD install process still cut out at exactly the same spot. the stubbornly persistent concentric grooves were, apparently, causing refractory distortion - but polishing just wouldn't make them go away!

In despair, I pulled out a small piece of 600 grit wet/dry sandpaper and - with a little spit as a lubricant, sanded the CD disc in concentric circles and back and forth across it's surface for about 2 minutes. the sanding obliterated the CD's glossy sheen - then I re-polished the CD with the Memorex/aluminum oxide goo and my lens polishing cloth. - not even to a mirrorlike gloss, but it;s sheen did mostly come back, though I could still see a lot of fine scratches on the surface.

When I popped the CD back in and ran the install process, LO! Like a charm - good as new.
posted by troutfishing at 9:24 AM on April 20, 2004

Actually, you don't want to do concentric circles when polishing a cd, you want to polish radially.
posted by substrate at 9:31 AM on April 20, 2004

I've had great success with tooth paste (not gel) on audio CDs that have had scratches affect playback. Rub from the center out. Works just like a rubbing compound.
posted by dirtylittlemonkey at 9:32 AM on April 20, 2004

> when I removed it from the CD tray it was in one piece but with some deep concentric scratches.

Concentric scratches and scratches perpendicular to the line from the center of the cd to the edge (yikes, a picture really is worth a thousand words eh?) are much much worse than radial scratches. They pull the reading laser "out of it's groove" sort of.

This is why you should always wipe a cd from the center out to the edge, not in circles.
posted by Capn at 10:52 AM on April 20, 2004

Also note that on some cheapie CDs that the foil is all that protects the write surface. Scratch the foil side and it's game over, man. Better CDs have better protection of the dye layer.
posted by bonehead at 11:25 AM on April 20, 2004

I've had great results with a two-step process that uses toothpaste for the first step, and brasso metal polish for the second. I heard about it here.
posted by vorfeed at 12:57 PM on April 20, 2004

Great thread...having spent an evening with 2 very fustrated ladies who were trying to watch a very scratched DVD of Sense & Sensibility, I will be trying toothpaste & vaseline. Feel free to add the punchline of your choice...
posted by i_cola at 3:00 PM on April 20, 2004

I should have clarified : the initial scratches were on the plastic side, not on the foil/medium side (the side with the print label).

substrate - the concentric scratches are real data/laser tracking killers, I know. I resorted to the sandpaper, finally, to cut the surface level down enough to wipe those damn radial scratches. Polishing just wouldn't do it. The job required an aggressive surface cut. I initially sanded my CD (with the 600 wet/dry) with radial motion ( little circles, really ) and then I polished it up with concentric motion. This seemed to work best.

The radial sanding takes down the CD surface quickly - it removes enough plastic to bring the surface level down to the troughs of the scratches. Concentric sanding might work almost as well, but it seemed definitely to be superior during the polishing stage. It would be at this point that you would use the toothpaste polishing compound (cut, maybe, with vaseline), and then to Brasso for the final buffing.


So :

Stage one : 1200 wet/dry sandpaper. My 600 paper was worn - it might now be equivalent to 1200 wet/dry. Be conservative - if the 1200 doesn't take the plastic down fast or radically enough, you can always go to a courser grade. Use a lubricant - water, vaseline, soap - anything will do as long as you don't use solvents which could melt the CD plastic and/or your fingers.

Use a radial sanding motion - little circles really.

Stage two : Polish with lens cloth, using toothpaste and lubricant. Mixed radial and concentric polishing.

Stage Three : Final buff with lens cloth (wash out residue from stage two first) and Brasso.

Stage Four : wash CD with soap and water. Pat dry with kleen, soft towl.

Enjoy!

P.S. - Make sure sandpaper, lubricant, lens cloth - everything with will be intimately in contact with the CD surface - is grit free. A small bit of sand in the works could really chew up up an already damaged CD which, then, would be truly farpotchket.

i_cola - sounds like an evening in hell.
posted by troutfishing at 9:11 PM on April 20, 2004

Oh, and - toothpaste and vaseline always bring prompt relief to a long evening's frustruations.
posted by troutfishing at 9:14 PM on April 20, 2004

Use a lubricant - water, vaseline, soap - anything will do as long as you don't use solvents which could melt the CD plastic and/or your fingers.

The polycarbonate used in CDs is water-permeable.
posted by five fresh fish at 9:22 AM on April 21, 2004

FFF - Well, they're not very permeable then : I got bored whilst fruitlessly polishing my damaged CD. So I took a bath while polishing some more, and would clean off the polishing compound residue by dunking the CD in the tub.

The polishing method was ultimately useless, but I haven't noticed any water damage (discoloration, I guess?), nor did the CD become flopy or soggy in the slightest.

Of course, submerging a CD in water for hours or days might be a very different matter! Maybe it's possible to reduce one by boiling it? I'll have to try that - just to test the parameters of their permeability.

But a brief dunk doesn't seem to faze 'em at all. They're tough little buggers really. That's my final conclusion.
posted by troutfishing at 1:28 PM on April 21, 2004