Dear Linda, Why do you need to soak any FFPE tissue in NAOH? If tissue
is properly fixed and well processed, cut on a decent microtome with a
sharp knife at the right temperature.
If there is calcium, use a surface decal. If there is a large volume of
blood clot try and cut the block warm'ish or soak in water for a few
minutes and then cool. David.

David Taylor
Laboratory Manager
Drs King & Mo