On Apr 12, 7:57 pm, "Brent" wrote:
On Apr 12, 1:39 am, wrote:

the problem with SHARPNESS is it is not a good measure of the
effectiveness of a cutting tool....

I have to agree w/ Brent.

Anyway, I thought this info tidbit might be of some interest.

Once upon a time (25 years ago)...
I worked in a Histology lab -a medical laboratory responsible for
preparing surgically removed biopsies for microscopic review and
diagnosis by a pathologist. The specimens were cut into approx 1/4" or
smaller samples and processed, eventually embedding them into a block
of paraffin wax. Three to eight micron thick slices of this embedded
tissue were cut using a microtome and then mounted onto a microscopic
slide for staining and review by the pathologist. Any knife nicks
caused drag marks and compression of the tissue (and cells) making the
sample of no value under the microscope. Some tissues contained bone
and other harder stuff like kidney stones or even teeth (rare).

The microtome consisted of an 8-10 inch knife fixed in position at an
angle of roughly 30 degrees from the verticle, and a mounted block of
tissue (about 1 in sq.) which passed over the knife, one rotation at a
time, producing this thin tissue slice similar to a peeling cut in
woodturning.

The knife was of a fine grained steel... (sorry but I didn't know
anything about steel at the time) and shaped like a wedge, about 30
degrees and 1 1/2 inches deep (8-10 inches long). The edge was
sharpened on a super flat, ectched, thick glass plate using some
watery toothpaste-like slurry. The blade was held at an angle and
passed over the plate in a figure eight pattern, then flipped over to
sharpen the other side. The passes were made mechanically and were
counted and timed. (Keeping the angles even) Each knife had its own
glass plate. Eventually, the glass plates were sent out for
resurfacing; i.e. etchnig and flattening.

And getting back to the point of the story:
In the end, blade sharpness was determined by looking at the cutting
edge under a microscope. Any knicks or voids left on the edge caused
the blade to be resharped until removed. But ultimately, the sharpness
test was how well it cut through the tissue samples. Some knives
lasted for only say 30 slices. Others would last for several tissue
blocks.

Take what you can from this example. I thought it might give some
perspective.

June in Denver