I think a Sharpie or other felt-tipped marker is OK as long as you don't press too hard. It's those ballpoint pens that cause the real problems. I was interested to read that labels can damage the CD though. I had always heard that using adhesive labels added an extra layer of protection and was therefore a good practice.

Jeremy Stoller
Senior Graphic Artist
California Science Center
(213) 744-2532
[log in to unmask]
www.CaliforniaScienceCenter.org