Been using Sharpie fine points on CE and DVD media for yrs....never caused a problem.
The only possible problem I could see would be on really cheap media that has a thin coating.
lol now that's one thing i haven't done yet but i either use a Sharpie or i use TY printable discs and my Epson R320 on the non-data side.Ditto .....
Once upon a time ,
I was looking through my Burned DVD Back-Ups
and noticed that one of the Discs looked
.... a little more purple than the others .....
As a result of trying to multiTask ;
I had written , With a Sharpie : On the Data side of the Disc
You would think ... that the Disc was toast - as I did
I took some rubbing alcohol and a soft cloth ( old , clean t-shirt )
Rubbed and rubbed until all the Ink was removed
( still ... Coaster - You would think - for sure .....)
... and guess what ...
The TY 02 Played - just as well as it should have
( Also scanned @zero errors via VSOInspector )
The Moral of the Story :
Sharpies are fine to use to Label your Media
( just don't label the data side )