How to restore scratched disc with the help of improvised means
Issue of the day: Scratched Disc
If you have ever dealt with scratched disc, then you probably know scratches
inflict sizeable damages on the disc contents. And how scratches appear? There
are various reasons of it as follow:
- Frequent use of the disc (at that CD-Rom itself can scratch the disc);
Careless treatment of the disc (for example, the disc is kept without its
- Casual falls on the floor;
- Other influences.
The result of scratches is such
sectors on a disc that laser can not read. Why that takes place? Because scratches
bend the laser path. As a consequence a laser can not reach information under
those scratches though that information is safe itself. In such a way scratches
close access to information on a disc, and make use of a disc uncomfortable
or even impracticable. For example, if there is a movie on a disc, then some
picture areas can "jump" or even stop because of scratches. All
those worries are able to mar your pleasure, of course. And, finally, it
is undoubtedly that there is no need in scratched areas in a disc with important
text documents! What is to be done?
Is data extraction from scratched disc a solvable problem?
As we learned on the Internet the data extraction is a subject of controversy.
Some people consider data extraction from scratched disc is quite
possible problem. Another people disagree to it. Someone else is in
doubt. Is there
the right answer generally? We did not found firsthand information about any
specific experiments. The sources existent either are low-quality or suspect.
To remove all doubts we decided to realize own independent experiment.
Methods of extraction
We know that there may be two approaches to the data extraction from damaged
disc namely program
method and mechanical
method. Program method lies in recovery of unreadable sectors
with the help of special programs (like the "Durable Copy" and the like).
It can read damaged files due to the fact that it lets pass all damaged
areas in them. Mechanical method lies in mechanical polishing
of the disc surface. This method can raise accessibility to data reading.
We would like to investigate the second method of scratched discs
recovery founded on the principle of polish. Because we want to recover
those data which may seem lost. We also use the program "Durable Copy" because
current standard tools for copying do not allow to extract data from a file
which is damaged even a little (in this case current standard tool usually
repotes of an error, and stops its work). And we want to recover every possible
Assume that polishing
of scratched disc surface allows effacing scratches entirely and/or making
them less deep. Then the problem of bend the laser path can be removed entirely
or partially, and information will be extracted from a disc. Let it be our
hypothesis. Being based on this hypothesis we have conducted independent experiment.
And now we illustrate this procedure process step-by-step, and show results
received. We hope it will be interesting for you to learn this information.
We hope you will find something useful for you.
We put the following questions as objects for experiment:
- Is data extraction from scratched disc a solvable problem?
- What gives the polishing method itself?
- Is it real data restoration because
of raising accessibility to a laser or not?
Restoration of scratched disc with the
help of improvised means
Stages of independent experiment:
There are 7 stages of this experiment:
1. We took absolutely new disc without any scratches and made testing of its ability to read with the help of the program for discs reading "Durable Copy".
2. We sizably scratched this new disc by means of sea shell with sharp edges, and a piece of granite.
3. Then we made testing of scratched disc ability to read with the help of the program for discs reading "Durable Copy". Also, we made a comparison with the original undamaged copy with the help of special program for searching differed files the "Sync Last Files Professional".
4. We took the disc and were polishing it for 30 minutes using usual toothpaste as an abrasive. At that we were polishing it for 10 minutes using medium rigidity tooth-brush, and then we were doing that for 20 minutes with a rag, toothpaste, and water.
5. And then we made testing of polished disc ability to read with the help of the program for discs reading "Durable Copy". And, again, we made a comparison with the original undamaged copy with the help of special program for searching differed files the "Sync Last Files Professional".
6. Further we were polishing the disc for 60 minutes more with a rag, toothpaste, and water.
7. And then we accomplish final testing of polished disc ability to read with
the help of the program for discs reading "Durable Copy". And, of
course, we made a comparison with the original undamaged copy with the help
of special program for searching differed files the "Sync Last Files Professional".
And at the end of this experiment you can read results received (summary).
Stage 1. Testing of undamaged disc ability to read.
Picture 1 and 2. We took absolutely undamaged disc without any scratches.
Picture 3. We put this disc into the disk drive, and run the "Durable Copy" to get original copy of the disc.
Screenshot 1. Here you can see we are ready to copy. We wish to copy the disc and use it as original copy in the future.
As the disc fails we will be comparing it with our original copy in order to understand whether we could restore data. You can see that there is disc data at the right column, and free catalogue for keeping original copy at the left column.
Screenshot 2. Disc analysis is in progress.
Screenshot 3. Copying process is going on.
Screenshot 4. All files were copied with success. No notice of errors appeared.
Stage 2. We are scratching good disc.
Picture 4. We prepared tools to inflict damages to the disc surface namely sea shell with sharp edges, and a piece of granite.
Picture 5. Doing damages to the disc. To complicate the issue of restore we intentionally did scratches of different thickness and form. Because transversal and longitudinal lines and zigzags are more dangerous to data.
Picture 6. We have scratched the disc sizably. At that all scratches were deep however not so much to damage informational layer, i.e., we did not scratch through the disc itself.
Stage 3. The testing of ability to read for damaged disc is going on.
Picture 7. We put scratched disc into the disk drive, and run the "Durable
Copy". We are interested in this program ability to extract data and to
check quantity of safe files.
Screenshot 5. The "Durable Copy" is trying to read our scratched disc. It is clear that some files are can not be read entirely, and another files can be read only partially.
Screenshot 6. Scratched disc has been copied. As the table indicates, there were copied 142 files with success (5%). There were read partially 2560 files. And 8 files can not be read entirely.
The fact of the matter is success in copy does not mean the files are safe. So we do byte comparison of data with the original copy, and use for it special program the "Sync Last Files Professional".
Screenshot 7. The "Sync Last Files Professional" indicates the result of comparison.
Screenshot 8. The result of comparison with close-up. There were revealed 2568 different files.
As the table indicates, there is difference in the total amount of elements which were shown by the "Sync Last Files Professional" and the "Durable Copy". There are several reasons for it:
The "Sync Last Files Professional" counts both
files and catalogues. For example, our disc has 469 catalogues.
The "Sync Last Files Professional" excludes from
results those files and catalogues which are the same because the program
is designed for different files and catalogues synchronization.
The "Sync Last Files Professional" will determine
to do synchronization when one catalogue has a file, and another catalogue
has not got a file.
From this it follows that the "Sync Last Files Professional" had to find 2568 files. There were revealed 2562 different files that is less than it was expected. Why? That might be because a part of copied files had empty data (e.g. damaged areas in empty place of large picture of BMP format). But the main fact that there are no more damaged files than the "Durable Copy" consideres.
Stage 4. Polish of damaged disc (the first time).
Picture 8. We prepared the following tools to polish damaged disc: a tooth-brush
of middle rigidity, and a toothpaste as an abrasive.
Picture 9. We applied a quantity of a toothpaste over a tooth-brush, and
began to polish the disc.
Picture 10. The polishing process was going on for 10 minutes
only, and then we took a rag.
Picture 11. We rejected a tooth-brush because of its unexpected scratch property,
and took a rag instead of it. We applied a quantity of a toothpaste over a
disc, and were polishing it for 20 minutes with a force and using some water.
Picture 12. After that we washed the disc. As you can see the disc surface
is not shining anymore. It became lustreless because of polishing. Scratches
appear through lustreless surface, and they are not so deep as before.
Stage 5. Test of ability to read for polished disc.
Picture 13. We dried the disc, put it into the disk drive, and start the program
for discs reading "Durable Copy".
Screenshot 9. There were copied 694 files with success (26%), and 2016 files were copied partially. There were not copied 0 files.
Screenshot 10. The result of comparison with the help of the "Sync Last Files Professional".
Screenshot 11. The result of comparison with close-up.
Byte comparison of copy received with the original copy which had been made with the help of the "Sync Last Files Professional" showed the positive dynamics. The "Sync Last Files Professional" has revealed the same quantity of different files (2016 files) as it were copied partially. The program has revealed all partially copied files. That means we improved ability to read. And that means data were really
safe under the scratched disc surface.
Stage 6. Polish of damaged disc (the second time).
Picture 14. Being inspired with our first success we applied a quantity of
a toothpaste over a rag again, and continued to polish the disc with a force.
From time to time we were moistening the disc with water, and then were polishing
again. This process was last for 60 minutes.
Picture 15. After that we carefully washed the disc with a warm water.
Picture 16. We wiped down the disc and saw the final result of our efforts. The scratches became less deep though did not disappear. Nevertheless we saw a progress in polishing process.
We put the disc into the disk drive, and run the "Durable Copy".
Stage 7. Final testing of polished disc ability to read with
the help of the program for discs reading "Durable Copy".
Screenshot 12. The program is copying data from polished disc.
Screenshot 13. There were copied 1099 files with success (41%). There were partially copied 1606 files. There were not copied 5 files.
Screenshot 14. Using the byte comparison, the "Sync Last Files Professional" has discovered 1582 different files.
Screenshot 15. The result of comparison with the help of the "Sync Last Files Professional" with close-up.
Once again we can see the positive dynamics. After long polishing we could read 405 files additionally, whereas we could read 552 files additionally after the first iteration. At general positive dynamics yet we can see the beginning of files progressive destruction because of long polish. We could not read 0 files after the first polishing, and we could not read 5 files already after the second polishing.
1). Extraction information from scratched disc with the help of improvised
means is a solvable problem.
2). The polishing method is real data restoration because of raising
accessibility to a laser.
3). At 1,5 hours of polishing we could extract 967 files (38%) from 2568 initially
damaged files. That was affirmed with byte comparison with the original copy.
4). Moderate polish improves data accessibility for a laser. Long polish
can lead to the data loss.
5). Polishing is good for small scratches but not good for deep ones.
6). Manual polish is laborious and time-taking process.
. All rights reserved.
No part of this document may be reproduced in any manner whatsoever without written permission
except in the case of brief quotations embodied in critical articles and reviews.
In the case of quotations link to source is strictly required.