Vote on knives - I'm for variety

From:Gayle Callis

Low profiles - Accuedge, Edge Rite (Richard Allan) and DuraEdge - not taken
the time yea or nay Shandon's, although these sit in a drawer waiting for
testing. The first three have good long lasting edges, same for their high

High profile (preferred by this lab for all routine paraffin use, even for
decalcified bone) - EdgeRite, DuraEdge, and AccuEdge.  Just tried Sturkey's
new Extremus blade, but need to extend evaluation time - it worked well for
two sample blades tried and about to be added to the list and should be

For frozen sections, we have returned to AccuEdge high profiles (first
choice), low profiles (second choice) time and time again and well worth
this pricey blade for quality frozens. Stability is critical in cryostat,
high is choice. EVERYONE in this research lab uses the same blade in
cryostats to minimize tweaky fingers on settings.   

I find no difference in sharpness of low versus high profile blades, even
different name brand L and H, but they ARE different for overall stability
during sectioning with thicker, wider highs giving additional stability for
chatter free sectioning.         

As for steel knives, we used these exclusively for very large, dense
decalcified bones - on a gigantic motorized sliding microtome.  I had the
pleasure of sectioning perfectly processed human femur head slabs with LOW
profile blades on a Leica 2035 (actually sold me on this microtome many
years ago!) The bones were prepared by highly skilled bone people (Linda
Jenkins et al) who took the time to have optimally prepared samples. Time
is money and maintaining steel blades in a one horse, whoops, one person
lab - for routine use is no longer cost effective even with a beloved
Shandon sharpener. 

One thing many people fail to do it use both high and low profile blades in
their labs, a convenience thing to use just one type - generally low
profiles.  Lows (narrower, low height) are not always ideal for cutting
dense tissue. Our lab changes blades according to tissue/project demands
from low to high or vice versa.  Unfortunately, some microtome
manufacturers are making it difficult to go from one blade holder to
another QUICKLY - sad but true!  Blade holder designs sometimes lock labs
into using one type of blade all of the time - not convienent, very
frustrating.  Microtomy was not designed as the science of being stuck in a
rut of rotten sectioning with just one blade type even on the latest,
marvelous microtomes available.  That is why there are both highs and lows
- to provide skilled choices for the BEST section at any given time on any
given tissue during a daily routine.  25 cents worth, folks!      

Variety rules here and higher price is never considered if a knife edge
lasts longer with flat uncompressed sections from every block.  Two cheap
blades without long lasting edges add up to one expensive, superior blade. 

Probable confusion for Vinnie (forget cost, go with what gives QUALITY!)
and a too longggggg lecture - 


Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
S. 19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)


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