by Katie Tavini, Audio Preservation Engineer, Unlocking Our Sound Heritage
When guests visit the audio digitisation studio at The Keep and we talk about which formats are endangered, a lot of people are surprised when we mention CDs, or more specifically, the CD-R.
In my job role as Audio Preservation Engineer, here at The Keep (which is the South East Hub for the British Library’s Unlocking Our Sound Heritage project), I come across lots of CD-Rs that have audio, images and text files on, from all types of sound collections. Unfortunately, there are some CD-Rs that are beyond saving, which means that unless there is either another copy of the material, the sounds it stored are lost forever.
Remember in the early-mid 2000s when digital cameras really took off. Family occasions, nights out, birthdays, day to day life. Everything was documented because there was finally no real limit on how many photos you could take – other than the storage size of your SD card. And when that storage ran out, you’d probably just dump all your photos onto a CD-R that you’d bought in a multipack at the local supermarket.
You see, at the time, external hard drives were fairly expensive, and not super accessible. However, you could go to pretty much any big shop and buy a 20 pack of CD-Rs that you could use to store whatever digital files you had. I know that I used to make compilation CDs and photo albums to back up my files, and to give to family and friends as gifts.
The shiny plastic discs seemed as though they were made to last forever. However, now might be a really good time to move all your photos and files from CD-R to a different storage medium.
CD-Rs are made up of a few different layers. But the part that actually stores all your stuff, is a layer of dye. When you burn a CD-R, the laser in your computer cuts a path in this dye. But over time, and especially with exposure to light, this dye can fade. When that happens, it makes it harder and harder for your computer to read the CD-R. This means there’s more chance of it failing, and you not being able to retrieve your stuff.
The diagram below shows the different layers of a CD, and a CD-R:
Also some bad news if, like me, you tried to keep your files super organised on CD-Rs – if you glued labels to the top, or used a marker pen to detail the contents (or doodle some fancy artwork), the chemicals in the glue or marker pen could also speed up the rate at which a CD-R degrades.
CDs, the type you typically buy pre-filled with music, are a little more sturdy, and will last longer thanks to the aluminium layer that contains a single spiral of data. The aluminium layer is read in a CD drive pretty much the same way the layer of dye in a CD-R is read, however, the aluminium won’t fade over time, giving it a longer shelf life. Fun fact – the spiral of data on a CD can be as long as 5km in length!
So no need to worry about your commercial music collection on CD, but do make sure you back up your home made CD-R photo albums – don’t lose precious memories to degrading formats!