CD-R Lifespan - Is It The Label?

sysadmn writes "Slashdot has discussed archival lifespan of CD-R media before. Fred Langa revisits the issue with a new twist: Are glue-on labels causing premature failure? Much more common than rain forest fungus! From Fred's informative LangaList newsletter."

Comments

I used to label my cds...

[Jarlsberg]

...but I've stopped doing that. For one thing, humidity causes the clue to come off, leaving you with a bubbly cd that doesn't fit in many slot cd players (esp. car players). Dragging the label off at this point will damage the cd.

How about normal CDs?

[Dancin_Santa]

What kind of protection do normal music CDs have to avoid this kind of rapid degradation? Is there any?

I haven't personally had any CD-Rs go bad on me, but I know a few people who have old CD-Rs that are unreadable in current devices. We chalked that up to a difference in formats, but it may have been this problem.

What is an acceptable digital archival media?

Re:How about normal CDs?

[temojen]

What kind of protection do normal music CDs have to avoid this kind of rapid degradation? Is there any?

Commercial manufacturers silkscreen their CDs, they don't use adhesive labels.

What is an acceptable digital archival media?

All media degrades. The trick is to use redundant data, and re-copy it before the media is expected to fail.

Re:How about normal CDs?

[Casshan-Robot Hunter]

Actually, for longevity, I would have to go with... stone. It can't hold as much data, but it seems to last millennia, especially if it is stored properly. Not the best for portability either, but longevity was the key concept here.

Re:How about normal CDs?

[Anonymous Coward]

"...and take care that UV light is kept to a minimum (i.e. fluorescent lighting is usually better than incandescent lighting)"

I think you will find that a fluorescent tube puts out more UV than an incandescent globe (halogens the exceptions).

A flourescent tube produces only UV light internally, which strikes a phosphor which fluoreses (hence the name), giving off visible light. Not all the UV output of the tube is converted; many places ban exposed fluorescent tubes for this reason, and require diffusive covers to be installed (when did you last see an office space with exposed fluoros? Now you know why: depending on where you are, it could be a building-code violation). Tubes without phosphor produce so much UV they are used to sterilize medical equipment (or erase EPROMS if you remember back that far).

An incandescent globe creates light from heat, which is the infra-red part of the spectrum. In fact, over 70% of the power used in an incandescent light is wasted as heat. Very little of the output is UV. Halogens are the exception, but the explaination is a bit too complex for a quick post; they do produce more UV than a tungsten filament globe, however.

I would suggest visiting http://www.sylvania.com/forum/ for more information, including spectral data.

Other than that, what you write is spot-on. Although, I have some additional suggestions.

Choose a brand of CD-R that has the data layer sandwiched between two pieces of plastic. Some types have the data layer directly under the printed label (certain TDKs, Laser brand for example), which can be scraped off with a thumbnail, or corroded by a single drop of moisture on the label. The outside rim of the CD should also have a line of laquer visible. If there is no line, don't use it for critical backups.

Buy the lowest speed CD drive you can find, put it in a sealed box on a shelf and only use it when you need to restore from backup. A relatively unused drive can frequently extract data that a more used but faster drive can miss (I suspect the laser loses output over time, like most light emitting diodes).

If it is that important, a fire-proof safe is an ideal storage container. Air and water tight, large thermal mass to reduce temperature variations, and best of all, nobody can walk off with your backups (short of a circus strong-man).

But most importantly: NEVER, EVER BACKUP TO CD-RW. Nuff said.

Re:How about normal CDs?

[QuackQuack]

Don't buy from stores that have humid, warm warehouses.

How are you supposed to know the conditions for the warehouse for a given store? I doubt even the employees of the store would know the answer to this.

Different Technology

[Maddog Batty]

Large batch produced CDs (such as music CDs, AOL CDs etc) are manufactured by stamping the CD pits into a thin layer of aluminium. This is then covered in plastic to protect it on the bottom and a layer of ink on the top. There is no dye layer to degrade with time.

CDRs have a blank die layer into which the CD writer burns the pits. This dye layer is what is causing the problems for long lifetime.