Maureen,
I haven't used this on extremely high heat, but it works on the immuno's I do. I
use a waterbath made up with 90% D.I. water, and 10% Elmer's school glue. (I use
plus charged slides.)  After sectioning, let air-dry for half an hour, then dry
at 60 C for 15 minutes, cool, and proceed to deparaffinize. The glue leaves no
background staining. I hope this works for you.
Lori