Hello Bonnie,

You mentioned that you "sub" the slides with Biobond, which is a
treatment, though not really subbing (like with gelatin-chrom alum). 
Biobond is a silanizing treatment (mixed with acetone, right?) and that
changes the glass surface to become positively charged so that the
negatively charged groups in the tissue "stick."  Gelatin won't stick to
it.  I suggest you really sub your slides with gelatin-chrom alum.  It
isn't any more or less complicated than doing biobond, and your gelatin
should probably stick to it.  I am not sure if the extensive
cross-linking from putting it in formaldehyde will alter its ability to
stick, essentially, to itself.  This is the way it used to be done, so I
assume it must have worked.

Good Luck,

Stephanie Moore