[Histonet] Re: Alternative to Histobath

[Robert Richmond]

Replacement for the Histobath rapid freezing unit, apparently no
longer in manufacture:

Alan Bright, at Bright Instrument Co. in England, notes that >>we
manufacture the Clini-RF Rapid Freezer which goes down to -80 degs.
(See our Web site) C. We also fit as an option a Quick Freezer into
our OTF5000 Cryostat.<<

Histobath consisted of a container of liquid cooled to a low
temperature by a freezer. The open pot was filled with acetone (or
2-methylbutane), and I thought it was an explosion hazard even at the
very low temperature the liquid was held at. At brightinstrument.com I
read that the liquid used in it was hexane, also a fire hazard in an
open container.

I understood that some people were using a hydrofluoroether in the
Histobath. Can this be used in the Clini-RF unit? The information I
had about this stuff was:

3M™ Novec™ Engineered Fluid HFE-7100
This product belongs to a class of fluorocarbons called
"segregated hydrofluoroethers (HFE's)"
According to various MSDS, HFE-7100 is
methyl nonafluoroisobutyl ether
C4F9-O-CH3
It melts and freezes at -135 C, so that it would remain liquid in the
Histobath. (It would freeze solid in liquid nitrogen, however.)
It boils at 60 C., and is listed as non-flammable.
It cost around $230 a gallon a few years ago.

Bob Richmond
Samurai Pathologist
Knoxville TN