# Why do scratched CDs get "stuck"?

**URL:** <https://boards.straightdope.com/t/why-do-scratched-cds-get-stuck/189368>\
**Category:** Factual Questions\
**Created:** [July 18, 2003, 12:02pm UTC](https://boards.straightdope.com/t/why-do-scratched-cds-get-stuck/189368 "2003-07-18T12:02:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\
**Post date:** [July 18, 2003, 12:02pm UTC](https://boards.straightdope.com/t/why-do-scratched-cds-get-stuck/189368/1 "2003-07-18T12:02:46Z")

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Just as the title says, really. The laser beam doesn’t touch the CD, so it’s not like a big scratch on a record that can guide the needle back into the previous groove.

As I remember it, as the CD spins the laser beam moves at a constant rate from the centre of the disc towards the outside, with the spin speed of the disc being adjusted so that the linear scan rate remains constant. So why does a big scratch confuse this process and keep the laser beam reading the same little segment of disc over and o isc over and o isc over and o isc over and o isc over and o…?

Am I missing something? Do CD players tell the laser beam to “back up” a little to re-read an area if they encounter errors or something?

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**Author:** ![Ice\_Wolf](https://avatars.discourse-cdn.com/v4/letter/i/dfb087/32.png) [@Ice\_Wolf](https://boards.straightdope.com/u/Ice_Wolf)\
**Post date:** [July 18, 2003, 1:16pm UTC](https://boards.straightdope.com/t/why-do-scratched-cds-get-stuck/189368/2 "2003-07-18T13:16:04Z")

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Some interesting info on this from a Yahoo Groups board [here.](http://groups.yahoo.com/group/earlyflute/message/52)

> [@](#):
>
> a scratch which runs at an angle to the track usually poses no problem for the tracking mechanism. Indeed a well adjusted CD player should be able to track a disk on which a 1mm strip of black tape has been stuck - providing it is stuck on radially. But if a scratch is approximately tangential or circumferential, it can obscure the track below for enough time that the tracking or error correction cannot cope.

The author suggests using Brasso as a fix-it for CD scratches. Would this do any further damage?

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**Author:** ![Mort\_Furd](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mort\_Furd](https://boards.straightdope.com/u/Mort_Furd)\
**Post date:** [July 18, 2003, 1:29pm UTC](https://boards.straightdope.com/t/why-do-scratched-cds-get-stuck/189368/3 "2003-07-18T13:29:44Z")

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It should not cause problems. Brasso has a very fine polishing grit in it, which is just what you’d need to make a clean repair. Because of the fineness of the grit, however, it could take a very long time.

Be carefull not to scratch the label side of the CD while polishing, and polish radially - from the rim to the center and back, then turn the CD a tad, rim to the center and back, etc.