CD-R Media Lifespan

Will those treasured files be readable in ten years time? Iain Laskey Investigates

So you've just bought a big tub of 50 shiny new CD-R disks and are now busily copying your digital camera pictures to them, safe in the knowledge that in years to come you'll be able to read them back and show your friends just how funny we all looked in the year 2004.

Fast forward ten years. You fire up Windows 2015 XP Media Deluxe Edition for Home and plug in your legacy CD drive. With trembling anticipation you insert the first CD-R. Within seconds the friendly voice of Windows purrs (in 14.1 digital audio, natch) 'I'm sorry, this media is no longer readable. Shall I fill in the online request for ecologically friendly destruction?'. ARGHHH!!!!!!

The Theory

CD-R media has a rated life span. A number that is often bandied about is about 75 years. On the face of it though, the things ought to last forever. After all, what can go wrong? In reality, quite a lot. The chemicals used to coat the surfaces are quite a feat of modern technology and not to be taken for granted. The key is the dye used. The laser in the CD burner heats the dye up rapidly to around 200C causing a change of chemical composition. The burned bits reflect light differently to the non-burned areas and this difference in reflectivity mimics the pits etched in 'normal' CDs.

When played back, the amount of laser light used is quite low so you can play them over and over with no ill effects. However, prolonged exposure to either heat or bright sunlight can start to slowly damage the surface. In time, the CD-R becomes unreadable.

CD-RW disks work in much the same way but employ chemicals that can change back and forth when burned. In this instance though, the chemicals change from a crystalline to a non-crystalline state. The result is the same - a difference in reflectivity. However, some older players have trouble reading CD-RW disks as the difference between the two states is subtler.

The main issue is that not all dyes are equal. Good dyes cost more to make than cheap ones. Branded quality disks tend to use better quality dyes. The bulk cheap CD-Rs you often find at computer fairs or online are sometimes made using poor quality dyes that will record and verify OK but over time will start to breakdown. In extreme cases you may find you can't play them back after only a year or so.

How to Improve CD-R Longevity

As has been noted, storing in a cool dark place is a good start. Another good idea is to use high quality media to begin with. As an example, HiSpace (www.hispace.com) have recently launched a new range of CD-Rs aimed at digital photographers. These disks use 24 caret gold to help add stability to the disks. As a result, they come with a 100 year warranty. For good measure, the disk inlay is laid out with photographers in mind with Date/Theme/Place headings. You may also want to check out HiSpace's completely excellent range of CD-Rs that look like old 45 singles complete with black surface and label in the middle. Mad but fun.

Another good brand to look at is Imation. (www.imation.com) Whilst they do not offer the 100 year warranty of the HiSpace disks, they are a market leader with many years experience in media of all types. They use very stable dyes in their CD-R production and you can be sure they'll not let you down as long as you treat them properly. Imation also do some rather sexy mini CD-Rs in nice neon colours as well as different DVD +/- media.

There are other ways to help preserve your data. Avoid touching the surface of the CD-Rs by holding them by the edges. Otherwise any grease or dirt on your fingers can start to damage them - especially the underside where the recording surface is. Equally, don't put them down on a worktop, keep them in their case or in the CD drive. Minor scratches can easily impair their readability.

If you use labels, make sure you have high quality ones which have been manufactured with adhesive that is safe to use on CD-Rs. This may sound silly but some cheap labelling kits actually employ glue that can damage the CD-Rs over time. If you use a pen to write on the disk, use a proper CD-R pen. Using just any old felt tip pen is a bad idea as the chemicals can damage the protective layer.

If you need to clean a CD-R, use a lint-free cloth. Finally, avoid humid conditions or letting moisture condense on the disk surface.

Conclusion

It's fair to say that taking the 75 year expected life span of a CD-R for granted is a bit optimistic. If your data is important to you then you really need to give it the best chance you can. Only buy good quality media and store/treat it properly.

 

Iain Laskey
See Iain's site at www.pcbookreview.com