In article , Dan Espen wrote:

Those Sharpies are pretty cool.
They do a great job writing on CDs too.
Lots of other inks just form drops,
The Sharpie ink dries smoothly and quickly even on glass.

There is a concern that the solvent in Sharpie ink will penetrate to and
ruin the data in a recordable CD because the data layer is so close to
that surface.

However, I have goten away with that so far, even with one recordable CD
where I saw from the data-read side the effect of the ink solvent actually
penetrating into the data layer and visible altering its reflection
characteristics.

- Don Klipstein )