I work in a research lab and have for 32 years.  We use a 30 minute each
station on our VIP for mouse tissue.  We used to complain on how crunchy
and difficult it was to cut.  Now they are a dream because we use Richard
Allen Flex 100 (diluted to make like 70,80,95 and then 100) and for the
clearant we use Pro-Par from Anatech.  Alcohols and xylenes were not good
at all for animal tissue.  For large tissues, rat to pig and sheep, we use
the same solutions but use a 60 minute time in each bottle.  It is amazing
how easy things got when we got rid of xylene on the processor.
Karen  Dulany HTL (ASCP)
Eppley Institute for Cancer Research
Omaha, NE