Naked Science Forum
General Science => General Science => Topic started by: neilep on 10/09/2007 21:04:27
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Dear Banana Cd Impresarios,
see this Banana ?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv280%2Fwithdrawnmist%2FDsc026t61.jpg&hash=efb951f9cd11d5960faec65e5260cbd0)
It's a little gloomy because it knows it's fate is sealed in curing an ailing scratched cd !!
I saw this video right ?.....(sorry..don't have the link)....but the bloke showed a well scratched CD to the camera....first he took some nana fruit and rubbed it on the cd, then he took some nana skin and (inside skin side) rubbed the skin on the cd..then...he took a cloth and wiped it...finished it off with some glass cleaner and voila !!...ALL the scratches were gone !!
Was this slight-of hand ?...or were nanas invented in 1982 to serve the CD cleaning fraternity...but mostly...how does a nana fill a cd scratch ?
I don't know what to do with nanas now..eat them or stick them in my cd player !!
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LOL.. I don't know either..LOL But I think I will try it! LOL! I have some scratched cds! Cool Post! LOL
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Firstly, I would be somewhat nervous of putting a D coated with banana into my CD player - may fix the CD, and destroy the player.
In any case, the problem with scratches is not the existence of the scratches, but the loss of information - can't see how a banana is going to recover that information.
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Firstly, I would be somewhat nervous of putting a D coated with banana into my CD player - may fix the CD, and destroy the player.
In any case, the problem with scratches is not the existence of the scratches, but the loss of information - can't see how a banana is going to recover that information.
Maybe (but I strongly suspect all the story is nothing than a legend) it fills the scratch with a substance with a similar index of refraction of the policarbonate thick layer. Information is not really lost if the scratch doesn't reach the inner layer (made of a different material and much thinner), where data are actually written. The problem with a normal scratch infact is just that light gets refracted casually from it, so the information read is modified, but the pits and lands in the written layer are not.
Probably there are better substances than banana, however!
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Maybe (but I strongly suspect all the story is nothing than a legend) it fills the scratch with a substance with a similar index of refraction of the policarbonate thick layer. Information is not really lost if the scratch doesn't reach the inner layer (made of a different material and much thinner), where data are actually written. The problem with a normal scratch infact is just that light gets refracted casually from it, so the information read is modified, but the pits and lands in the writed layer are not.
Probably there are better substances than banana, however!
My own suspicion is also that it is a legend. I would also doubt that the transparency of banana is anything like that of polycarbonate - so you won't read very much underneath.
In reality, the problems with CD's are not technically the loss of information (there is so much error correction on CD data that a fair amount of lost data can be tolerated without being noticed - and this is even more the case where we are dealing with analogue data, where a loss of a millisecond of sound would in any case go unnoticed - although it does depend on the direction of the scratch - a scratch perpendicular to the tracks is less problematic than one parallel to it). The bigger problem is that a break in the track can cause the CD to mistrack, and I cannot see that a filler that would allow laser any better ability to follow the track.
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THANK YOU THANK YOU THANK YOU ALL
George, Karen & Alberto
I found the video ..here it is
http://www.metacafe.com/watch/748070/the_banana_cd_scratch_remover/
comments ?
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THANK YOU THANK YOU THANK YOU ALL
George, Karen & Alberto
I found the video ..here it is
http://www.metacafe.com/watch/748070/the_banana_cd_scratch_remover/
comments ?
It does prove how effective bananas and window cleaner can be it making a CD an effecitive shaving mirror.
What it failed to do was either demonstrate that the CD with those scratches was causing any problems when played on a CD player, nor did it demonstrate how the CD played after the treatment.
Hope you like the shaving mirror, but sorry, it has not at all convinced me that I would wish to use a CD in a CD player after doing that to it.
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blimy arnt bananas great, you can eat them as well [:0]
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This reminds me of the days where I was quite active (as a hobby) in B1W photography. I had learned that scratches in film could be covered with glycerin.
The problem with a scratch is that it distorts much more than the actual scratch itself. When you enlarge a negative with a scratch, this scratch will show on the print much wider : because the light is diffracted, the scratch will partly cover the surrounding "information". But what showed as a thick line on the print without the use of glycerin will become a very thin line when the negative has been treated.
I may be the same thing with you CD : irregularities (like scratches) in the protective layer will diffract the laser, which will fail to reach not only the pits beyond the scratch, but also those around it. Filling the scratch with a material with the same refractive index would solve the problem.
There were lots of other products rumored to be the perfect remedy, but banana peel was not among them. And in my limited experience, glycerin gave the best results.
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This reminds me of the days where I was quite active (as a hobby) in B1W photography. I had learned that scratches in film could be covered with glycerin.
Nose grease has also been used to fill the scratches in negatives.
Nose grease can be used to minimize scratches in optical surfaces, for example when cleaning photographic negatives.
http://en.wikipedia.org/wiki/Nose_grease
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This reminds me of the days where I was quite active (as a hobby) in B1W photography. I had learned that scratches in film could be covered with glycerin.
The problem with a scratch is that it distorts much more than the actual scratch itself. When you enlarge a negative with a scratch, this scratch will show on the print much wider : because the light is diffracted, the scratch will partly cover the surrounding "information". But what showed as a thick line on the print without the use of glycerin will become a very thin line when the negative has been treated.
I may be the same thing with you CD : irregularities (like scratches) in the protective layer will diffract the laser, which will fail to reach not only the pits beyond the scratch, but also those around it. Filling the scratch with a material with the same refractive index would solve the problem.
There were lots of other products rumored to be the perfect remedy, but banana peel was not among them. And in my limited experience, glycerin gave the best results.
Don't see that being an issue when you are reading something with a laser beam.
What might be an issue is if the laser beam were to be redirected to an adjacent tract (i.e. if the scratch was deep enough to cause the beam to refract on its angular walls, rather than diffracting, and so believe it had picked up something from somewhere else - this may be worse than picking up nothing).
All of it might be more believable if the demonstration had actually shown that - but the video only showed that an apparently superficial scratch was no longer visible to the naked eye - it certainly did not demonstrate that it had any positive outcome in the use of a CD in a CD player - which is the important matter regarding CDs.
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The video was there to demonstrate the relief of scratches on the CD. I don't think I've made a comment abut the functionality of the Cd afterwards...nor does the video in fact !
However, as a firm believer in empirical study I do have one of the most scratched CD's ever...(of which I have made a copy)..I will in due course follow the instructions in the video and see what happens...and will document it for your wondrous perusals.
THANK YOU ALL AGAIN for your interesting valid comments.
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THANK YOU THANK YOU THANK YOU ALL
George, Karen & Alberto
I found the video ..here it is
http://www.metacafe.com/watch/748070/the_banana_cd_scratch_remover/
comments ?
Thanks for the video, you described the proceedure perfectly! Thanks
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I found this comment from Robert about Bananas really interesting for a thread on cleaning shoes with banana skin! Do You remember Neil, a topic by Hannah!
http://www.thenakedscientists.com/forum/index.php?topic=3165.0
ROBERT
Guest
MessageID: 25304
05/01/2006 17:45:24 ยป
Shoe polish is primarily wax.
Banana leaves contain wax:-
http://asae.frymulti.com/abstract.asp?aid=14121&t=2
so it is possible that banana skin also contains wax,
and could be used as a polish.
http://www.channel4.com/4money/goinggreen/features/save_shine_100604_page2.html
Could this be true of the CD cleaning also??? I would think it basicly the same principal!
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Firstly, I would be somewhat nervous of putting a D coated with banana into my CD player - may fix the CD, and destroy the player.
In any case, the problem with scratches is not the existence of the scratches, but the loss of information - can't see how a banana is going to recover that information.
Maybe (but I strongly suspect all the story is nothing than a legend) it fills the scratch with a substance with a similar index of refraction of the policarbonate thick layer. Information is not really lost if the scratch doesn't reach the inner layer (made of a different material and much thinner), where data are actually written. The problem with a normal scratch infact is just that light gets refracted casually from it, so the information read is modified, but the pits and lands in the writed layer are not.
Probably there are better substances than banana, however!
Hiya Handsome and this is interesting info...
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the laser reflects of the reflective coating on the disk and not the bottom scratched part. If the scratches are so bad, you just need to fill them with something of the same density and transparency. Nitro glycerene works well I have heard. Give that a try.
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I have used metal polish and it worked well enough for me to read and copy the cd.
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the laser reflects of the reflective coating on the disk and not the bottom scratched part. If the scratches are so bad, you just need to fill them with something of the same density and transparency. Nitro glycerene works well I have heard. Give that a try.
You could use C4 explosive as well... [;)]