BTW, never
write on a CD with a felt-tip pen or magic marker. The ink
can easily seep through and affect the laser's ability to read the
data. Labels are a bad idea, too, as they will cause the disc to spin
out of balance.
So how are we supposed to label them, buy a 30-micron layer lacquer
machine?
Its a solvent issue, just buy a pen made for labeling CDs. TDK makes one
for less than $2. Personally I use whatever is handy short of a ballpoint.