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Re[6]: [AV Media Matters] Polishing of CDs

Hi Joe

Joe> Point one -- The polishing with the Fix-a-Disc equipment was done
Joe> by the owner of a used audio CD store.

Fine - I accept this as a fair a test as any.  It was reasonable for
you to assume this guy had the necessary experience and would know
whether or not his machine was set-up correctly, etc.

Joe> If there was a problem with his technique then that is fair game
Joe> and it is a result that should be noted.

I am very concerned about the disc which remained on the machine for
several hours with no improvement.  To my mind, this should have
resulted in no disc :-).  To me, this indicates that all the other
tested items should be taken with a pinch of salt.

Joe> Obviously, my testing has indicated some potential problems.

Yes - I agree.  In fact, even more so now you have explained the
circumstances under which your test was made.

Joe> Point two -- I have not "publicly damned" any product


Therefore, from this small study it is evident that polishing
appears to be hit or miss. It may improve scratched discs to some
degree but may also make discs worse. This was especially evident in
the unscratched CD-R that was put through the process (as a control).


Well, that sounded pretty much like a damnation to me, particularly
since I was under the impression, at the time, that these tests had
been carried out under laboratory conditions - but I accept I may have
read more into it than you intended.

I *do* agree with your general conclusions, but only to a certain
level.  This is mainly because I have serious doubts if the gentleman
doing the work was really on top of his job.

Joe> The original post simply wanted to know if any such measurements
Joe> have been made.

I do know that Digital Innovations (manufacturers of the 'Doctor'
range) have graphs available showing the reduction in errors that may
be achieved using their devices. I have no idea how these were
produced, or what measurement criteria were used.

We have used one of these graphs for display and advertisement
purposes, but I'm sure you will appreciate that, as a mere importer of
the things, we rely on our principals to provide us with this sort of
information.  We can't go rushing off at a tangent (even if it was

I *will* ask the question of them - maybe I shall be able to let the
group know a little more about their findings.  Granted, as
'manufacturers information' they will only release that which shows
the product in a good light (we have to be realistic here) but we also
have the experience of many end-users of the product as well. While
this may be subjective in nature, that is no reason to discount it

As far as the Fix-A-Disc is concerned, I honestly do not know if any
truly scientific tests have been undertaken with this machine - but
again, I shall ask the question.  In the meantime, there is a slew of
subjective support.

Joe> I would welcome some testing of discs that you have polished
Joe> using the process that you use.  I had no vested interested
Joe> either way. Please e-mail me and we can discuss.

For the moment, I think it would be more interesting to others if we
stayed in the public forum.  I suspect there are others interested in
this subject.

I could send you discs, but it might be easier for all concerned if
you were to deal with our principals - CD Repairman - it is, after
all, their neck  which is on the block.

Actually - and don't hold me to this statement - I think it likely
they would welcome some independent testing of the results they can
achieve.  I will talk to them and ask if they would be willing to
submit items for testing in this way.

Joe> "Sloppy science". I never indicated a thorough many year 100 disc
Joe> study. I did indicate a small study indicating some problems.

True, although you did (inadvertently, I accept) give me the
impression that the test was a lot more controlled than it actually
was.  On the other hand, although a small sample, it did show that
there probably many other factors which impacted the result.

In fact, knowing what you do about the tests, added to knowing what I
do (about the machine itself) I would seriously suggest that the
results you obtained be discounted, since I honestly believe the
machine and/or operator was not really working at its optimum.

Joe> What is sloppy science is evaluating a treatment without concrete
Joe> data. Yes, end result -- how does it sound? -- is important, but
Joe> this is very subjective. Data eliminates any bias. We need both
Joe> factors to establish the effectiveness of a process.

Well... it's probably true to say that those here are certainly
interested in data.  But in the commercial world. data doesn't really
count for all that much - particularly when you consider the general
lack of knowledge about the subject for the 'man in the street' (see
my remarks in a previous post).  For this person, subjective criteria
are actually *more* important, if only because it is a judgement he
can make for himself.

Joe> I was surprised that no such data was available for the many
Joe> processes out there.

Well, in truth, there are not really that many processes :-).

1. There is disc grinding and polishing - which, if we leave out one
method which employs a bench press drill, boils down to three
manufacturers who are actually in production - plus a couple of others
who have yet to produce anything on a commercial basis.

2. There are a number of 'repair kits' which seek to replace material
(lost through a scratch) with something with a similar refractive
co-efficient as the polycarbonate.  This is usually some form of wax,
either in suspension or dissolved in a carrier fluid.  After
application, the latter evaporates off and leaves the scratch filled
with whatever.  Generally this is not very effective as the 'filling'
falls out (probably due to thermal cycling and mechanical shock) and
needs to be re-applied - of course, it usually falls out while the
disc is being played.  In truth, these should not really be regarded
as 'repair' at all, more 'patch-up and get you home'.

3. The third group comprises materials intended merely to clean the
play side of a disc of general grime and crud.  These latter hardly
fall into the same class, as they are not sold as 'CD repair'
materials.  However, they may well have some interest to archivists.

Joe> If you are pushing a product or process you should have concrete
Joe> data to support it.

I am not entirely disagreeing with you about this either.  But you
have to understand that people in my position are *highly* reliant on
our principals.  All we can practically do is to ask the questions and
hope we are given some useful answers.

Just as a side issue, I can think of two devices, one of which is
widely used in archival circles and the other, which might be, if it
were not so expensive - neither of which has much in the way of
'concrete data' to support them.

One is the Monks record cleaning machine - many thousands of which are
used in record archives and libraries all over the world (in fact,
most of them are in such organisations, as they are far too expensive
for the average private individual).  I have the literature for this
machine in front of me and there is a lot of wonderful stuff about the
'improved transparency' and all the other guff which 'hi-fi' reviewers
introduce into their reports - but no solid data to back this up.
However, I doubt there are many archivists who wouldn't agree it is
useful and effective device.

The other is the (somewhat mythical) ELP turntable.  The pros and cons
of this device are not germane to this discussion, but I seriously
considered the purchase of one of these machines at one time. Although
I was in direct contact with the president of the company and received
all sorts of stuff about its mode of operation, plus audio tapes
purporting to show how it improved the sound - again there was no data
published.  Even so, in spite of this fact - and its undoubted high
price - there are certainly some people out there who would give their
right arm for one :-)

Graeme Jaye


Audio Restoration and CD Repair

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