cryostat knives, safety and storage of knives to be used

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From:Gayle Callis <>
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Hi Vinnie et al,

I use the cryostat almost exclusively these days, having to put a knife in
and out of the holder is out of the question.  One loses tract of the edge
just used in relationship to the new edge, a real issue with me, not having
that good edge available.      

A handy knife guard, learned this one from Lamar Jones, simple, cheap and
effective, plus totally disposable in a biohazard box, is remove the little
"v" shaped paper spacer from a microscope slide box (supply is always there
and unlimited) that fits perfectly over the edge of a blade without
damaging the edge.  You could put a tidge of double stick tape inside to
attach gently to holder.  This also works over regular microtome knives. 

Little flexible magnetic strips can be modified to create a knife guard
(like the vendors supply us at NSH meetings for magnetic decorations!)

Our unused knives are stored in a freezer always at or around cryostat
cutting temps, so the knife is removed cold, and ready to go, why wait for
it to cool down, lots of foot tapping and gnashing of teeth when that
happens. IF you had to put a used knife in the freezer, it would have to be
in a ziplock baggie, sealed to biohazard carryover contamination, best if
it is left where it is, until used up, in the holder! This works nicely for
C profile knives that have boxed, but disposables can't be put back into
their holders, and cryostats tend to be cramped for space.

Constant removing of a used knife and then replacing it is a pain with more
chance of dinging a lovely sharp edge (expensive), and time lost (time is
money also, patient has to wait some more!)  The biggest danger, in my
estimation, is reorientation of a block face to the edge. Have seen people
never use an available guard to protect their fingers. 

An excellent suggestion on educating safety officer(S) who could be guilty
of being a  a bit "nit picky". Safety can be achieved without removal,
replace, removal, replace, etc etc ad nauseum. I prefer to leave the knife
in holder until the edge is used, have also learned to clean around it
(with knife guard on, using 70% alcohol on guaze held with a longggggggg
straight hemostat and leave my precious edge ALONE!    
Try Lamar's suggestion, recycles and protects!

Hope I got the picture here, just stepped in.

Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303

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