> And what are these advertisements I see on the web for 'CD Resurfacing'?
Do
> they actually take your CDs and mill the bottom surface?
Yep. There are CD Resurfacing machines (cheapies start at a grand and go up
to somewhere around 5-7k usually) which do exactly that. You put the CD in,
it removes a layer from the bottom of the disc and then polishes it up. If
there are still scratches (i.e. they were really deep) you just repeat the
process. A typical CD can be resurfaced this way at least five times. After
that you run the risk of the disc becoming too fragile but this differs from
disc to disc as to the actual limit.
The CD Resurfacing machines are usually sold to video and music stores. A
lot of rental places (local stores, not chains) should have them as well as
music stores that deal in used CDs. They usually charge a buck or two to do
the resurfacing.
Unless you have a really messed up CD, I wouldn't bother with the
resurfacing. You can easily remove minor scratches with some baking soda
toothpaste, running water and your fingers. More stubborn scratches can be
removed with EXTREMELY fine sandpaper, running water and your fingers. In
either case the principle is the same. You are not really removing the
scratch, instead you are removing the surrounding plastic.
This is what a typical CD scratch is like. The data layer below the scratch
is still fine, but the sudden jump due to the scratch can cause the laser to
misread.
This -----] [-----
text -----] [-----
is -----] [-----
here -----] [-----
to -----] [-----
keep --------------
This is what a typical CD scratch looks like after it has been repaired with
a home remedy. The sudden jump has been turned into a soft curve so it no
longer disrupts the laser.
the -] [-
filter --] [--
from ---] [---
cutting ----] [----
the -----] [-----
art. --------------
A resurfacing machine will totally remove the scratch, but you will then be
left with a thinner CD. It is the same as slicing a layer off of an onion.
Adam