CDs Are Not Forever: The Truth About CD/DVD Longevity, “Mold” & “Rot”

DVD Stack   CDs Are Not Forever: The Truth About CD/DVD Longevity, Mold & RotThe digital age has revolutionized the way we handle information. Never before could humankind record and store so much information and in such diversity. While the amount of data has increased exponentially, the predicted life span of the storage media hardly exceeds the lifetime of a human. For humans who love to collect and leave a legacy to their descendants, as well as human kind who so much depends on information, this poses a huge challenge.

Optical discs have been commercially available since the 1980s. After merely 30 years, a solid amount of information has been collected on what causes CDs and DVDs to break and much progress has been made in the development of material that will last longer. While estimations predict a life time of up to 200 years for optical discs, we can never be sure when they are really going to break. However, by being aware of what determines the life span of optical discs and what causes them to break, you can make choices and significantly increase the survival time of your stored data.

Let’s examine this case in detail…

What Determines The Life Span Of Different Optical Discs?

To understand what limits the life span of optical discs, let’s look at how they are built-up. What all optical discs have in common is the presence of three key layers:

  • coating layer that protects the reflective layer.
  • shiny layer that reflects the laser.
  • polycarbonate disc layer that stores the data.

In addition, a label is applied above the coating layer and re-writable discs contain a dye layer between the reflective and protective layers.

Disc Layers   CDs Are Not Forever: The Truth About CD/DVD Longevity, Mold & Rot

One factor that determines the maximum life span of an optical disc is the type of reflective layer. Other factors include the overall quality of the raw material and manufacturing and most importantly the way the medium is treated by the user. The handling of an optical disc probably has the most significant impact on its longevity, hence we will re-visit this theme in a moment.

It is hard to predict exactly how long an optical disc will last since it depends on so many different factors. Nevertheless, estimations are floating around that predict a life span of up to 200 years for recorded CD-Rs and Blu-Ray discs. The shortest life span with 5-10 years is predicted for unrecorded CD-Rs and CD-RWs, followed by recorded DVD-RWs with up to 30 years. Recorded CD-RWs and DVD-Rs have a predicted lifetime of 20-100 years. In other words, you should not rely on any of these media for lifelong storage of your precious data, as they are likely to fail sooner rather than later.

How Do CDs or DVDs Rot?

As mentioned above, different types of optical discs contain different layers and particularly the reflective layer is subsceptible to damage. Standard compact discs typically have a reflective layer made from aluminum. When exposed to air, aluminum oxidizes, which naturally happens around the edges of the CD. However, degradation of the reflective layer is not the only cause of disc rot.

The causes of disc rot are manifold and can include one of the following:

  • oxidation or corrosion of reflective layer
  • physical damage to disc surfaces or edges
  • galvanic reaction between layers and coatings
  • chemical reactions with contaminants
  • ultra-violet light damage
  • breaking down of disc materials, e.g. de-bonding of adhesives between layers

Interestingly, while most types of disc rot are caused by inappropriate use and/or storage, there is one in particular, i.e. CD bronzing, which is caused by a fault in manufacturing.

How Can I Check Whether My Optical Discs Are OK?

You can do a simple visual check. If you see light shining through tiny little holes when you hold a disc against light, then the reflective layer has started to disintegrate. Also check your CDs for discoloring, especially around the edges. See whether the different layers are still tightly together or have started to de-laminate. Finally, you can try to copy the optical discs to a hard drive or scan them for data integrity using different software, e.g. CDCheck or dvddisaster.

Blue CD   CDs Are Not Forever: The Truth About CD/DVD Longevity, Mold & Rot

How Can I Increase The Lifetime Of My CDs & DVDs?

There are many ways you can increase the likelihood that your CDs and DVDs will last you a long time. Here is a selection of the most important ones:

  • Choose a high quality medium from a good brand.
  • If you want to maximize CD longevity, go for gold as a reflective layer.
  • Treat your CDs and DVDs with care, i.e. hold them by the outer edges or the hole in the center, don’t touch the surface, avoid scratches, and keep dirt from the disc.
  • Keep them in a dry, dark, and cool place since humidity, sunlight, high temperatures, and pollutants can damage the different layers.
  • Store them in jewel cases rather than paper slips.
  • Use non solvent-based felt-tip permanent markers, suitable for writing on CD or DVD labels.
  • Rewrite your rewritable discs as little as possible.
  • Choose slow writing speeds to reduce errors and increase quality.

What Can I Do When My Disc Won’t Read?

A disc that can no longer be read by your player or shows errors is not necessarily a lost case. Here area few tips for what you can do to:

  • Make sure you didn’t accidentally insert the CD or DVD upside down.
  • Carefully clean the bottom layer with alcohol to remove grease from fingerprints and dust.
  • Try to read the CD or DVD in a different player. Chances are that the laser in your player is faulty or that a different player can still read your CD or DVD.

Conclusion

Always have a backup of your data and check all our backups regularly to make sure none of the copies have broken in the meantime, regardless of whether you store your data on a CD, DVD, or hard drive.

What kind of data do you store on optical discs and how do you back up software, music, or movies you buy on a physical disc?

Image credits: DVD Stack via Shutterstock, CD Layers via Wikipedia, Blue CD via Shutterstock

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91 Comments -

Justin Winokur

This is one of the reasons that CDs really do not make sense for any type of backup. You are so much better off with an external drive. Or, even better, an online service. Let them take care of checking the integrity of the data. I use Backblaze since they let you backup your external drive as well, but there are other good services as well.

Even if the disks lasted forever, ~5gb is not very much. It isn’t worth the effort.

Tina

Very true, Justin. 5GB doesn’t hold a whole lot of anything.

Truth

5GB definitely holds a lot. Thousands of music, all your high school/unversity work, all your photos, etc. It’s huge man!

Daniel

5GB only holds a thousand MP3 320kbps and that’s low quality. CD quality files can be 10 times the size (100 songs) of a 320kbps MP3 file. 5GB is enough to hold 1 DVD. Optical media is good for 1 thing alone – distribution. Though, with 100Mb connections only twice the price of 10Mb connection and 250Mb to 1.5Gb+ connections being on trial for a long time from various providers; I cannot see optical discs being a standard distribution format for much longer.

Dave

320kbps MP3 is CD quality, idiot.

Enn Ellandi

Tanks Justin just checing out Backblaze

abhijeet

well,this was another great article from you tina! before,i never really thought
about this issue of longetivity.your site truly is heaven for geeks!
the knowledge and information on this site is amazing!personally, i store music,
videos,e-books and all the useful geeky information on the optical disks.
i recommend readers to use the online cloud storage as well.

Tina

Glad you enjoy our articles, Abhijeet!

Truth

The article is good indeed, however, for this, and all others that think the ‘cloud’ is a good solution. Haha! Right now, it seems good, but, it won’t be in the future. Why? b/c 1st, you’ll be ruled by these companies that hold all your important things. Once they start charging you for it, they’ll monetize every single penny you’ve got. 2nd, don’t depend on others to hold your precious data. Every day, a new type of virus is release and you’re at risk of losing the internet by some hacker in China altogether. External hard drive I think is the best bet right now.

Tina

Good point regarding the risk of losing access to the internet.

Ben

The only time I use CDs/DVDs is when I deliver software to clients (and this is very occasionally). External HDDs are the way to go.

PS: You can’t leave a legacy to your ancestor! They have already left. Its your ancestor who leaves you a legacy.

Tina

Thanks Ben! Occasionally, I do reveal that I’m not a native speaker. :)

AriesWarlock

100 years is plenty to store your data. Anyway, I think I remember some sort of spray for discs to re-strengthen the coating. I forgot it’s name.

daddydave

The only company that ever claimed (and even then I am taking the word of the resellers because I don’t speak Japanese) 100 year lifetime of data on their premium disks was Taiyo Yuden, now owned by JVC.

Even then, all it takes is one scratch on the DVD and at least part of it is unreadable. That can happen in the first year.

Tina

Taiyo Yuden acquired the JVC optical media storage branch to use their name, which is far more popular in Europe and North America than Taiyo Yuden itself. JVC has since been exclusively supplied with optical storage media by Taiyo Yuden.

Greg

Very good read for someone who has dozens of Linux DVDs (me :D)

Davin Peterson

I’ve found that you can only write to a CD-RW/DVD-RW so many times before it goes bad or files get corrupted. So, I don’t burn CDs/DVDs much anymore.

I’ve also heard, that is better to keep the CD/DVD standing up rather than laying down, to keep it lasting longer

Truth

David, I’m sorry, but you are wrong. With a high quality CD/DVD-RW disc, it doesn’t matter how many times you re-write, the disc will remain the same. It’s just like your hard drive. You can delete and download new stuff all day, it doesn’t change anything. Over a long enough period of time, the motor on the needle may malfunction (b/c it’s a mechanic moving part) out, but the disc is still fine.

You “heard” that standing your discs upright is better; well, you heard wrong my friend. It doesn’t make a difference.

Ann Fennell

If the disc is in a jewel case, it doesn’t matter if the jewel case is horizontal or vertical, since the only part of the disc that is touched is the edge of the center hole – the rest of the disc is suspended in air.

Richard Steven Hack

I’m sorry, but the estimates of life spans are just that – estimates. No CD or DVD has been around long enough to make statements about a hundred years and I absolutely do not trust “guesstimates” the industry makes about longevity of anything.

The reality is that I’ve found CDs and DVDs written just a year or so ago and stored in a untouched CD case to have gone bad. Not entirely, of course, but at least one file will not be restorable and usually multiple files.

As for prerecorded movies DVDs, I’ve had several of my movies start to go bad after just half a dozen plays, necessitating me to rip them before they go completely bad.

This is why I NEVER use data compression on file backups being put on a CD or DVD. Because if you lose one byte of a compressed backup, you lose it all (unless you can use some sort of archive repair utility to recover the rest.)

Backing up to an external USB drive is also iffy – because those drives have a horrible reliability record, especially if they’re moved around much. Many of them die within a year or so of being used. I have a Western Digital MyBook Essential which has held up for the past year or so – because I almost never touch it.

The best backup targets are hard drives sitting in a computer, followed by a second copy in an offsite location – either a cloud drive or another hard drive sitting in another computer somewhere.

Never trust what the industry tells you about anything having to do with reliability – they’re usually either wrong or outright lying.

Laga Mahesa

Ever had a DVD go completely transparent after 4 months stored in a box in a closet? That was a laugh and a half.

Ann Fennell

what brand was that?

Tina

I second that. It’s been just about 30 years that CDs hit the mass market and only about 50 years since the technology was invented. The estimations are based on lab conditions and predictions. In reality, the average cheap medium will not last as long as predicted.

musicphann

I’ve had DVD’s and CD’s go bad in the 4-6 year range. And those plastic storage sleeves are awful. Even at normal room temperatures I’ve had them create sticky plastic imprints on discs that have rendered them unreadable.

Shane La Horie

I have been looking for something like this for a while now. Thanks.

And then there was Quo

My 1989 Status Quo CD is still working right now – and that’s been very well used, so I’m happy!

Tina

Fingers crossed!

Sudesh

Humidity and high temperature also damage the CDs. Cheap writable CDs use cheap dye which oxidizes quickly in hot and humid conditions. You can actually see tiny holes through the shiny reflective layer when that happens.

Laga Mahesa

Just to warn people who read this, the issues Tina listed are amplified if you’re in a warm/tropical climate.

The dye used in writable media does NOT like humidity.

Tina

That’s absolutely right. Since humidity and temperature contribute to the ageing of CDs and DVDs (and Blu-rays, too), a warm of tropical climate will make them break down faster than a colder and dryer climate.

Oron

Spot on. I have plenty of anecdotal evidence that in tropical zones, optical discs develop problems *very* quickly. What is more, even in Scotland (which is wet, but where our discs were well protected), I’ve seen some discs develop faults over as little as two years.
Optical discs are still a good means of transporting data, and even for making certain types of backups, but can’t be relied on for Archiving. Hard discs, while much more long-lived, should also be refreshed every few years.
Two other problems that affect the longevity of data are the drive connectivity
and data format. When was the last time you tried to read a 5 1/4″ floppy? What would you do if you had one and wanted to read it? This will be the case with IDE drives in about 10 years! Likewise, it is already difficult to read Word 97 documents (because MS have disabled the converters by default), or AppleWorks documents. In five years time, attempting to read either will be a major headache, involving searches for old systems to read them on…

In short, anyone who is serious about their data should transfer their backup to new media every few years, and convert it to a current (preferably open) format.

Tina

As always, great advice, Oron!

Nick Bruce

I never did understand why people insist on having CD backups. They made more sense when external hard drives were expensive, but in the day of the $70 2TB drive, it doesn’t make an logical or financial sense to use CDs.

Humza

Pardon me for reading all the content above and then asking…what about Blu-ray? Well i’m sure it hasn’t got the mass production and popularity level of CD/DVDs, but do Blu-rays rot and disintegrate over time as well?

Tina

Blu-Rays are essentially built the same way as CDs and DVDs. The difference lies in the laser and how densely the data can be written on the disc. So yes, they will also disintegrate over time.

Robert P

Is there and physical difference between the 3 disc formats(DVD,CD,Blu-Ray) at all? Because they certainly like to charge more for the DVD than the CD and even more for the Blu-Ray.

I’m pretty sure their just screwing us over royally.

Tina

I’m pretty sure there is, but I’m afraid I don’t know the details. They all use different lasers. Blu-ray lasers have the shortest wavelengths. The laser is in the blue spectrum, hence blu-ray. I’m sure this also requires different material to be imprinted.

Ahmed Khattab

and what are the trusted brands of DVDs in the market ?
how to distinguish the original from the fake ?
what is the ideal writing speed ?

Tina

1: JVC Advanced Media, i.e. Taiyo Yuden.
2: Common sense?
3: Not sure, slow to medium speed, probably 4x or 8x max.

Rob O’Neill

I bought my first music CD’s in 1985 and they are still going strong. Data CD’s may be different, especially rewritables. Any thoughts on the copyright issues of ripping all my CD’s to a new terrabyte hard drive? Do i own the music on the CD’s? Also, video tapes. Most of mine have turned to mush. Can I rip them without going to jail??

Tina

Rob,

copying ‘copy right protected’ CDs, DVDs, and video tapes remains a grey area. It really depends on what jurisdiction you fall under. Generally, you can make a backup copy for personal use. As long as you don’t sell either the original or the copy, you should be safe.

Gotit

How about using Millenniata’s M-disc (http://millenniata.com/m-disc/) for long term storage. Seems to have stood up to some intense testing at China Lake.

Tina

Sounds convincing.

Pressed CDs and DVDs are actually made in a similar way. The data are pressed into the polycarbonate (plastic). They last longer than burned CDs or DVDs, but still they disintegrate because the reflective layer (typically aluminium) oxidizes. So theoretically, replacing that layer could restore the data. Dyes are used for rewritable or burned CDs and DVDs.

LCW

The U.S. DOD did extensive tests on the Millenniata m-disc and ultimately gave it a milspec clearance as the most durable optical storage media currently available. If it’s so durable I’m stumped by the lack of m-disc capable drives on the market. I’ve contacted the company and they say more manufacturers will be forthcoming. Gotit – have you used an m-disc drive?

Tina

I haven’t used M-discs and doubt that I have ever owned a drive compatible with them.

Anthony

Very informative. However the more important thing to consider is how will we read these discs? If history is any indicator of the future we will eventually be hard pressed to find something to read these discs.

Tina

Absolutely right.

Robert P

That “shouldn’t” be as much of a concern as it was in the past since we now recognize this phenomenon and can take steps to prevent it. Since old technology is far from obsolete when the new tech comes out. We usually have several years to recopy to the new format/media before it becomes impossible.

Of course, I said “shouldn’t” because well humans may be the most intelligent species to ever exist on this rock, but we’re really not the brightest. :-/

Kirk Bubul

This is a good article. I’ve read a number of articles talking about the shelf and service lives or CD/DVD, both burned and blanks. Patrick McFarland’s (http://adterrasperaspera.com/blog/2006/10/30/how-to-choose-cddvd-archival-media) I found really instructive. For my “keeper” discs, like recovery disc sets and backup copies of application software, I use higher quality Taiyo Yuden discs bought from SuperMediaStore.com which guarantees that their TY discs are genuine. (I am *only* a happy customer. I have no link to them.)

While I use external HDDs for my periodic backups, I find good use for CD/DVD blanks.

Tina

Thanks for the recommendation! Taiyo Yuden seems to be the best manufacturer. In Europe and North America Taiyo Yuden media are sold under the brand name JVC.

Robert P

Something I was just thinking about for long term storage of a disc.
Since light, moisture, heat and oxidation are the main culprits in the degradation of the disc itself. Might be a good idea to slip them into a food vacuum sealer bag with an oxygen absorber and a desiccant pack. Kept in a cool, dark location.

With the moisture and oxygen removed the materials shouldn’t be able to oxidize. With no light, the cloudiness that occurs and several other things should be stopped as well.

Too bad testing is pointless since by the time we “really” know they will be obsolete. Oh well. Maybe something to try as soon as the new tech comes out in a big way.

Tina

Yes, this way of storing CDs should definitely increase their lifetime. There are also big vacuum sealer bags for fabrics, which could come in handy for storing a CD collection.

REM

One of the recommendations was to “go for gold as a reflective layer”, so far, the only DVD I own to go bad was a gold layered one.

Ann Fennell

I had the same experience. I bought a box of gold-layered CDs and found that the DVD/CD writer on my new computer would neither read nor write them. And that box, when I bought it was nearly $50.

Hoku Sarroca

guess i will have to back up everything on my external drive, I’ve stored a lot of old pics on the discs. and I will make sure I keep them in the dark area . Thanks for the great info!

Tina

Most welcome. Hope your files on the CDs and DVDs are all fine.

Manide

CDs were good for my CD audio player…
CDs/DVDs were good for data backup – personal projects, photos, music… (I’ve tried several burning apps; ImgBurn and BurnAware were my favorites).
Now they are indispensable when I need to create an Acronis rescue media or an “whatever antivirus” rescue disk.

Pete

If cds and dvd’s aren’t forever what happens with vhs tapes mine from 1999 are still playing,ever think it may be just simply a ploy by the industry to generate more revenue.Oh and I do use discs and again going back to the early 2000s.Simply scaremongering,storage up to a point is important with tapes apart from that discs are just that…Discs scratch em overheat them,like tapes get buckled or knotted in a old machine,worse case scenario…Pete

Scott Maurin

those tapes will start oxidizing sooner or later. I lost a bunch of cassette tapes that were boxed, inside in a closet. External drives can fail too, so best to have a couple of options.

Colorbars

Yeh, Scott is right, soon your tapes will start get molds too and even if you preserve thr tapes, time will come that your vhs machine’s will nor function normally and spare parts are no longer available. Better transfer them into new format.

Andrew Ray

Question: What is the lifetime for a external hard drive if you fill it up, unplug it and store in a cool dry place?

Tina

Andrew,

The lifetime of an external hard drive is just as hard to predict as that of a CD or DVD. Generally I would say 3-5 years when used regularly. Maybe up to 10 years when stored as you say. The difference is that it’s usually the mechanics that fail on a hard drive. So even if it does fail, you can most likely recover the data from the platter. When a CD or DVD fails, however, the data are gone.

Peter Kennedy

In regards to accessing files like pictures 50 years from now, consider, how many of you still have a 5 1/4 inch floppy drive, a 3 1/2 inch floppy drive, a parrellel printer port on your brand new computer? Who is to say that the harware to read CDs and DVDs will, even exist 50 years from now? Will USB ports still exist or be long superceded by some newer, faster interface? I have paper based photos from my parent & grandparents that are more than 70 years old and still in excellent condition. While the digital revolution provides us with marvelous advances I wouldn’t wish to give up, it is quite possible that planned obsolesence and technoological advances will prevent us from leaving similar legacies to our descendants that are easily available and affordable. Our CDs and DVDs are very likely to go the way of 78 records – dumped because the technology to play them is rare and/or expensive.

Tina

You are making an excellent point, Peter. Hence it’s important to always port backups to the latest and most affordable and secure storage medium. Currently that would be external USB/SATA hard drives.

Golf girl

The best long-term solution for preserving family photos, videos etc for 100+ years is purchasing an archive from Gen-Ark. Check out their website for more information. http://Www.gen-ark.com

Chris

I must be paranoid :)
I have a full online back-up (sugarsynch) plus I use a local NAS + other usb hard drives (1 per machine) and my precious stuff also gets burned to archive quality DVD.

paleolith

Chris,

You are not paranoid; you are wise and intelligent to duplicate backups.

Tina

I second that.

Chris Lloyd

Thanks :)
@ Peter K I agree that paper is a great way but it too can be destroyed – look at the recent storms in US and the fires in Victoria, Australia!
I am a keen genealogist and a relative of mine had all their photos and documents ‘safe’ at home with no duplicates – the house was destroyed by a fire started by a faulty heater!
I keep my precious original docs in a 3 hour rated fire-proof safe, but even that won’t guarantee that they don’t get damaged or destroyed so there a electronic duplicates!

Gotit

Remember the rule, “1 is a copy, 2 is a backup!”

David Kupy

From your article:
“Use non solvent-based felt-tip permanent markers, suitable for writing on CD or DVD labels”
Is a Sharpie, which probably everyone uses, solvent-based or not? If it is what specifically should we use?

Gotit

Sharpie actually makes a version of their pen specifically for writing on CD/DMD media.

KRC1023

Umm… Off topic but just wondering… What exactly is a “DMD”?

Gotit

That would be a typo. Should read “CD/DVD”.

Tina

As Gotit says, Sharpie makes pens specifically for writing on digital discs. Regular permanent markers are solvent-based. If they are not, they usually advertise as CD/DVD/Blu-ray compatible pens.

Ray

Nice article. I also use either Taiyo yuden media or Verbatim (the ones made by the Mitsubishi Kagaku factory) and try to burn them at low to medium speed. There is no need to hurry else you’ll just end up with a coaster.

I also read that it is best to store dvds/cds upright rather than flat to avoid them getting deformed. Another suggestion would be to always have a proper backup strategy and keep multiple copies in different media and test the data on each regularly to see if it works.

I personally have an external hard drive which I use for most backups and also transfer important files to DVDs as well. Though HDDs are cheaper, they are not reliable and they will fail someday. There is a lesser likelihood of failure with DVDs and though they may fail one day, they work for me as a secondary backup.

Frank

Taiyo Yuden is being censored and excluded in the Netherlands! Now I have to order them in Germany, because I want the best for my archived data. I’ve seldom had a problem with a Taiyo Yuden disk (about 3 failed disks out of 1000)! All other brands deliver poor quality disks; so custormers in the Netherlands need to (buy new disks and) reburn their data every 10 years.

Tina

Frank,

Thanks for the information. Do you happen to know why Taiyo Yuden is not available in the Netherlands? Does this mean JVC is being censored and excluded?

Frank

Luckily JVC is available in online shops!

In the mid 90s It was Philips which did a test (with many brands of CDs) among the folks on gathering.tweakers.net and 95% choose for Taiyo Yuden!!!

From that time on Taiyo Yuden was excluded and later censored in the Netherlands. This said, TY was still available, though not identifiable any more, because the major brands (Sony, Fuji and Philips) were selling them periodically.

Beezy

I have burned CD’s that are over 20 years old and work fine. I trust CD’s and DVD’s for backup more than flash drives and external HDD’s. I’ve lost countless files from hard drive failures and corrupted flash drive files.

Now that storage space is so cheap I try to backup all my important stuff in multiple places, because as my instructors used to say in school, if you don’t have copies of your files in at least 3 places, it doesn’t exist.

Tina

Beezy,

Backing up in as many places as possible and using different media is definitely the best you can do. Great advice from your instructors.

Ann Fennell

It was helpful, but would have been much MORE helpful if you had suggested several brands of quality CDs/DVDs, along with the strong and weak points of each.

I don’t use paper sleeves, but I do use non-woven fiber sleeves that are in small CD-sized “notebooks” and these weren’t addressed. Is there something wrong with storing them this way? It is of course, a darker space for the CD/DVD than a jewel case would be, but in a jewel case, nothing actually touches the disc except for the center hole.

Thanks for the article,
Ann

Tina

Ann,

You make excellent points and I have addressed some of them in previous comments.

Each article has a time and a word limit and thus the amount of detail I could go into was limited. I decided to list the most important points regarding storage. I also decided not to go into verifying which brand is the most reliable, since this is easily found when searching Google: Taiyo Yuden aka JVC.

Brad S

Great article. So the 200 year number you came up with for CD’s. where did you find this? Also is the the lifespan for recordable cd’s? What is the estimate for pressed music cd’s? Should I expect the same lifespan for a store bought Beatles cd for example?

Tina

Brad,

The numbers are from OSTA.org (source) and are based on estimations from manufacturers for CD-Rs. How exactly they ended up with this estimation I don’t know.

Generally, professionally pressed music CDs are predicted to have a longer lifespan than self-recorded CDs. That’s because they do not rely on an extra layer necessary to write data to the CD.

The life-limiting layer of pressed CDs is the reflective layer. Since that layer can oxidize and degrade, I would say expecting a lifespan of more then 30-50 years is being optimistic.

Brad S

But 30-50 years is less than the CD-R’s 200 years. I thought you said professional cd’s would have a longer lifespan?

Tina

I said that, but I didn’t say that I believe the manufacturer’s estimation of 200 years. I don’t.

James Grimes Jr

This is why I do not even use optical media anymore. I use flash drivers to install an OS, carry install files, or more data. However, for some of these tasks, using online storage seems to be a better option.

Susan Sinclair

Hi,
Some of my blu-ray discs have a transparent appearance. Have you any idea why this is? Have they been damaged by the alcohol a colleague might have used to clean them?

Tina

Susan,

Are these discs still playing alright?

And what exactly do you mean with transparent appearance?

Ethanol alcohol should not have damaged the discs. Different types of alcohol, however, can potentially damaged the plastic, which may cause a milky appearance. But you said transparent, so I’m guessing that’s not it.

homa

hi justin! Im master student in iran univercity for biotechnology. do you have any information about some molds that remove data from disketts and data storage device?
i would be lucky if you answer me.