Reviving scuffed DVDs Featured

Toothpaste has a very fine grit.

What do they use on windscreen chip fillers? Sadly there are some DVDs and CDs which resist even the best very fine Perspex polishing systems. My theory is that the actual material is flexible enough to be slightly hairy when polished creating enough scattering to make the reflection to noise pretty unworkable. DVDs are worse if they are of the multi level type of course which requires very precise focussing. Another problem you can get is that a dig on the label side will destroy the seal and oxidisation of the layer will start. On cds you find this causes the surface to first turn a bit brown then white. Brian

Toothpaste is finer than T-cut.

And there are metal polishes as well

Brasso?

Tim

Good sugestion, but l already tried it. I also tried toothpaste and another car paint cutting polish called G3 made by Farecla. I don't think the fine scratches are the issue so much as the 'bloom' - the slight fogginess. Perhaps I should try some isopropyl alcohol and see if that shifts it.... :-/

I could find one article that claimed there was a vapor phase technique for this. But Polycarbonate isn't exactly the most cooperative plastic.

Reading a DVD or CD, requires that the optical drive "lock" to the groove signal. Ordinary optical media has a spiral pattern in it. The groove signal follows the spiral. The head positioner uses the groove signal, to track the groove as the disc rotates.

If the groove circuit does not lock up, then no data can be recovered.

As soon as the groove locks up, Reed Solomon error correcting codes (multi dimensional) aid in error correcting the hard to read data.

When a disk has become unreadable, it is usually not the fault of Reed Solomon, but rather that the groove detector has lost lock and cannot match up to the spiral pattern.

DVD-RAM discs, have concentric circles scribed on them rather than a spiral groove. And there, acquisition of the groove isn't quite as non-intuitive. If you move the head radially, you'll eventually pass over top of a concentric groove, and the optics will see it. Whereas if the head is just sitting static over top of spiral media, the spiral intersects the head only once in a while. They must try to "match speed" to find the spiral or something. I've not seen that part explained.

Paul

I'm guessing that's why they say you should only polish out scratches

No and whereas a 45rpm single would survive a person sitting on it a dvd or cd will crack from the middle and then its ruined forever. Brian

CD data as you say is just circular tracks, but there is also a central part which when written to can make the disc finalised for no more writing.

Apparently there are some very expensive decks driven by bespoke software that is supposed to allow recovery of cds and dvds, but it can be a very long and tedious process apparently. For me I just get annoyed that a cd written at only 12 times from a master can fail to play completely in a dvd or cd player even though it said there were no errors, and this with a write once disc. Some of the older CD only writers are far less finicky here. Brian

Have you thought of actually coating it with a very shiny transparent film? I did attend a product that was supposed to work this way for CDs, but I doubt a dvd would work with it. I've not heard of it since, so maybe it only lasted while you retrieved your data and rewrote it. Who remembers those cds with holes in them that you could not hear? Brian

Duraglit as we are being silly. Brian

No, but I tried the next best thing: silicon wax polish. Still didn't work, though.

Nearest thing I could find was Brasso, which also comes as a wadding polish. Not sure if there's any difference in the fineness of the grit between the two. Brasso does seem to be very mild indeed - pongs remarkably like T-Cut - but leaves a foggy residue behind.