[HN Gopher] Documentary heritage: fungal deterioration in Compac...
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Documentary heritage: fungal deterioration in Compact Discs
Author : Hooke
Score : 45 points
Date : 2022-12-26 18:03 UTC (1 days ago)
(HTM) web link (heritagesciencejournal.springeropen.com)
(TXT) w3m dump (heritagesciencejournal.springeropen.com)
| shiftpgdn wrote:
| I think if you vacuum sealed the disks it would help prevent the
| issue.
| tristor wrote:
| You would think this, but I don't think it's true. Effectively
| sealed optical discs still get fungal growths. I think the
| fungal spores are already on or in the disc
| foobarbecue wrote:
| I have a DVD bought off of ebay. It's probably 20 years old, but
| never opened. It was a soccer-teaching video for kids that my
| girlfriend bought because she starred in it as a kid.
|
| When we opened the package, we found that there are ~100 raised
| white spots on the surface of the disc, about 1mm diameter. They
| don't wipe off easily. We haven't been able to get the disc to
| play. I would love to know of a good way to clean these, and also
| what they are -- fungus hadn't occurred to me before but seems
| possible.
| twawaaay wrote:
| For what is worth I have successfully dealt with scratched CDs
| by applying a cream that I found to be almost the same
| refractive index as the plastic of the CD.
| WalterBright wrote:
| Sometimes helmet grease works, too.
| nvrspyx wrote:
| When I was young, I had a few scratched PS2 games that
| wouldn't play. Some advice on the internet was to put
| toothpaste on the CD, gently rub it in small circular motions
| around the CD with a paper towel, then rinse it off. Perhaps
| I'm misremembering, but I remember being surprised it worked
| for most of them.
|
| It might've been specific to PS2 games and whatever material
| they were made of and/or how they were pressed, so I wouldn't
| recommend it as general advice. This thread just reminded me
| of it.
| rzzzt wrote:
| Toothpaste is a mild abrasive, if the scratches weren't
| deep it removed them entirely.
| twawaaay wrote:
| I still feel that a fluid that can fill the scratches and
| cause them to basically disappear is much better.
|
| If the CD is damaged the goal should really be to read
| the data once, then throw it away. So I think it is fine
| that the filling/oil/grease is one time only because I
| don't need it to work more than once.
|
| With toothpaste there are risks. There is the risk that
| the scratches are deeper. Not only you will not be able
| to polish it out, you can get toothpaste particles in
| there permanently.
|
| In any case, applying oil is just so much easier -- you
| only need to wipe the CD with it and then wipe the excess
| thoroughly.
| rzzzt wrote:
| I've heard the same advice for treating light damage on
| an LCD screen. The deciding factor between using either
| method should indeed be the depth of the scratch (and how
| well you can estimate it).
| rasz wrote:
| Article is about CD-Rs, afaik those used organic dye. DVD you
| bought sounds like pressed one = no organic materials. Whats
| more DVDs are build in a way where the data surface is
| sandwiched between two sealed polycarbonate platters.
| codetrotter wrote:
| Try using a piece of cloth, some water, and a little bit of
| dish washing soap
| Springtime wrote:
| Yeah, from what I've read from optical disc enthusiasts[1]
| isopropyl or plain dish soap with a cloth rag is suitable for
| cleaning. Anything that can cause abrasion like paper towels
| are best avoided.
|
| [1] http://www.digitalfaq.com/forum/media/12002-maintenance-
| opti...
| neilv wrote:
| Be careful with isopropyl. I've seen 70% or 91% poured over
| the print side of a movie DVD, causing it causing the
| printing to slough right off.
| foobarbecue wrote:
| Update: rubbed a bit harder with some IPA and they came right
| off. Now I just have to find a working dvd drive. Edit: I did,
| and the disc works fine! Imaged and ripped it.
| IIAOPSW wrote:
| It might help a lot if you could post a picture of it.
| SoftTalker wrote:
| I have never liked the CD/DVD media. As much as its durability is
| alleged, I have not experienced it. They are very sensitive to
| scratching and must be spotlessly clean to work. In the hands of
| children, I always had better luck with VHS tapes.
| tgv wrote:
| They don't have to be spotless. Audio CDs at least also play
| when scratched and dirty-ish. I don't recommend it, because the
| dirt can fall off and accumulate inside the player, but I've
| had very few problems. I got my first in '84 or '85, and all
| but two of 500+ still can be played back. I've never had a
| problem with a DVD, but they are considerably newer.
| layer8 wrote:
| Audio CDs are still able to play back with significant bit
| errors (CD players just interpolate over the unreadable
| parts). It's different for CD-ROMs and data CD-Rs.
| account-5 wrote:
| I can't be the only one amazed that fungi is biodegrading these
| materials. Fungus really is an amazing organism we don't know
| enough about
| jacquesm wrote:
| Aluminum based CD-R are a bad choice for this, if you want to
| have CDs that last long (or DVDs for that matter) you should use
| gold based ones, they last a lot longer than the aluminum ones.
| They are also quite a bit more expensive.
|
| Look for 'Archival Grade' or something similar in the product
| name.
| brazzy wrote:
| AFAIK, there are no aluminum based CD-Rs, the silver-looking
| ones actually have silver or silver alloy reflective layer.
| lmmgc wrote:
| [Account created by mistake]
| brazzy wrote:
| Gold doesn't oxydize. AFAIK that is a problem that
| _sometimes_ affects aluminium based discs, when the
| polycarbonate seal is defective.
|
| If you want to be really sure of maximal shelf life, you'd
| use glass instead of polycarbonate as well - the
| manufacturing technology exists:
| https://www.theabsolutesound.com/articles/the-2000-cd-
| made-f...
|
| But all of that is really not relevant at all for backups
| because the CD-R dyes will degrade long before the reflective
| layer. The shelf life of the reflective layer is an issue
| when talking about pressed discs.
| hguant wrote:
| Because gold is incredibly non-reactive?
| docandrew wrote:
| CD-Rs always smelled vaguely like celery to me, I wonder if this
| has something to do with it?
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