Finally had to get into the mix about marking pens.  We have been using the
pens from TBS (Triangle Biomedical Sciences, sold to us through Fisher), #
H-MP-B.  We have found them to be great on all cassettes and slides.  They
do not, however, write very well on baggies, a Magic Marker is better
there.  The Sakura Pigma pens write well on slides, but don't last on
cassettes.
	If you are writing with a #2 pencil or the black magic marker from
tissue
tek, if you will dip the lead into formalin and then write the writing will
be much darker and does not come off very well (on cassettes you will have
to use xylene to get the lettering off).  Hope this helps.  Cheryl