All, The discussion of blades and their properties is a favorite and quite
an old subject of discussion. Robert Hooke 1665, in Micrographia, first
described "the cutting edge" and he made an image of the edge.  He also did
the first free hand sections of cork and described the cells that were
revealed. For almost 200 years after that description microtomists continued
to use the "straight razor" cutting edge to prepare thin sections. " the
blade " has not only its utility to divide objects into thin sections but
also political and religeous symbolism. "war and peace". A proper blade must
have the blessing of a "high priest" figure ( in our time ISO 9000 Q.C. ) I
could go on and on....Check the edge to be free of nicks and swipe it free
of oil, Teflon, or wax. Adjust the cutting angle for the correct clearance
of the bevel. Lock the blade in place. Set your tissue block firmly in a
CLEAN and firm microtome clamp. Be certain that the tissue block is cooled
to the optimum temperature for its cuting quality ( each is somewhat
different ) say a prayer to St. Robert Hooke ( the father of the tissue
cutting edge )  and most certainly you will succeed (most of the time). Good
Cutting...J.B.mcCormick M.D.
-----Original Message-----
From: MTitford@aol.com [mailto:MTitford@aol.com]
Sent: Wednesday, June 20, 2001 2:53 PM
To: Histonet@pathology.swmed.edu
Subject: SEM of disposable microtome blades


I have enjoyed the discussion of microtome blades and Dr McCormick's and
Nancy Klemme's comments.

A few months ago I thought I would do an SEM study of disposable microtome
blades. I especially wanted to compare some 20 year old American Optical
blades which were the best I have ever come across, with modern blades, some
boxes of which appear defective on arrival.
Also examined were blades which had become scored through use, cutting
through small calcium deposits etc.

Suprisingly, there was not a lot of difference between these blades on the
SEM. Very good blades and "so, so" blades looked similier. Only blades with
obvious defects looked markedly different

There must be some other factors involved in how sharp a microtome blade is,
besides the appearance of the edge.



Mike Titford
USA Pathology
Mobile AL USA