Wednesday, March 2, 2011

Appropriate Care for CDs

George Blood Audio and Video uses these machines from Rimage to create
and thermally print labels on CDs and DVDs.

This is what I want to do:  I want to digitize the taped oral history memories of my mother, save them to CD, and then store the CD in a safe and secure place.  Then many decades later, my great-great great grandchildren will find it, pop it into a 22nd century CD player, and hear the voice of their great-great-great-great grandmother telling the stories of her youth.

Chances are it won’t happen quite like that.  But I at least want to start the process following 21st century protocol for best preservation practices.  For advice, I turned to Cassandra Gallegos, Preservation Administrator at George Blood Audio and Video.  An expert in audio preservation, Cassandra knows the weakness inherent in CD technology and has good recommendations for minimizing their impact:

Thermal printing on CD.
“CDs have a number of preservation concerns.  Optical discs consist of various layers. Their metallic reflective layer categorizes them.  This layer can be either gold or aluminum.  If air reaches the base of an aluminum disc through either a deep scratch or a manufacturing defect in the protective lacquer top coat, the metal will oxidize (rust).  This phenomenon is referred to as CD rot. Gold discs do not suffer from CD rot but have higher starting error rates.  These errors are unnoticeable
at first because of the built in error
CD with writing on hub.
correction system; however, by the time errors start becoming a problem, the CD is very close to being over run by errors that can rendered the CD unplayable.

“The way you label a CD is a preservation concern as well.  CDs should never be labeled using a any pen that could scratch or make indentations on the label.  This is because the information within a CD actually sits closer to the label side.  Many people
lay a CD to rest on its label side thinking this will keep scratches from damaging the CD but a scratch on the reflective side of a CD can often be buffed out while a scratch on the label side might destroy the CD.  There are various CD labeling markers that claim to not harm the informational layer.  These pens have not been around long enough to have any evidence that the ink will not damage the disc.  Paper labels can cause a disc to spin unevenly in a drive and are susceptible to water damage.  We use a special thermal process to print ink directly onto a specially coated CD.  If a special CD printer is beyond your price range, you may safely write on the clear inner hub of a CD without fear of losing the information.”

© 2011 Lee Price

No comments:

Post a Comment