Problems in Histopathological Technique
IMVS Division of
Woodville, South Australia 5011
DID YOU KNOW
Did you know that a highly polished bevel on a knife is
more important to cutting a good section than sharpness?
When you look at the edge of a sharp microtome knife through a
microscope you can often see a fine burr running along the edge
or a fine crystalline structure running through the metal.
Neither edge is good for cutting fine, thin sections. The edge
needs to lose the burr and the crystalline effect and become
more amorphous and slightly rounded. This can only be achieved
by highly polishing the edge. A high polish effect can only be
produced by stropping.
While on this subject one of the problems with disposable knives
has always been a high failure rate. Many just don’t cut at all
and if you look at the edge of these knives you will often see a
burr or the fine crystalline structure just mentioned. The knife
edge is just not sufficiently polished.
As funny as it might sound, the edge of these knives can often
be recovered, for wont of a better word, if the knife is used to
rough cut a block before fine cutting. Rough cutting tends to
remove the burr and polish the edge sufficiently for good
sections to be obtained or the blade can be stropped before use.
This is a photograph of new blade edge (Feather S35) taken straight
from the cassette and stuck under the microscope at a magnification
of 400x. It is not a good edge and would give trouble to even the
After minimal stropping to remove the burr and slightly round the
edge, this is a photograph of the same blade at the same
magnification. I reckon this edge could be used by any novice to
produce a reasonable section.
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© Roy C. Ellis 2002