Hacker designed a dry ice bucket to lower the temps on knife.  You could
try placing a piece of solid dry ice on blade and also icing the block
face, one way is to let the dry ice sit above the block, permitting the
very cold C02 (at this point, the dry ice converts to gas) to sink down over
the block face.  Have heard this works with paraffin, for very thin
paraffin sections on kidney biopsies. This may be a way to achieve the
extreme cold for fat in synovium, be sure to lower cryostat temp if you
try this. Putting dry ice directly on block could potentially crack
the OCT, maybe not.

We prefer to use the Instrumedics, which cut mink skin (containing 
an unbelivable fat content and consistency!) and held the skin components
together. 

Gayle Callis