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Subject: Preparing cross-sections

Preparing cross-sections

From: Terry Conners <tconners>
Date: Wednesday, January 21, 2004
The query solicited information about preparing cellulose acetate or
similar sheets as a support medium for fiber cross-sectioning, with
the objective being fiber identification. This is an interesting
problem. Some years ago I worked in a paper microscopy laboratory,
and while we routinely identified various natural fibers from
lateral morphology, occasionally we made cross-sections of fibers or
paper handsheets (etc.) for various reasons. Our method was
quick-and-dirty, but perhaps it might produce acceptable results in
this case with a minimum of effort. Casting cellulose acetate sheets
might not be necessary.

In a nutshell: We froze the fiber specimens with liquid nitrogen,
then we broke them in half with a single-edge razor blade held
vertically in a homemade handle.

There are two components to be fabricated, an insulated box and a
handle for the razor blade. (1) What we did was to take a small
styrofoam box (about 15 cm x 10 cm by 5 cm deep) (used to store
electron microscope filaments, as sold by the vendor) and we cut a
rectangular well into the box. The size isn't important, but don't
cut all the way through the depth. We then placed a rectangular
brass plate into the well. (2) The handle for the razor blade was
made of brass with a rubber-covered handle (think of friction tape
or perhaps laboratory tubing). We cut a slot into the other end with
a hacksaw so that a razor blade would fit into the slot, then we
drilled and tapped a hole in the handle so that the blade could be
secured with a small screw. Voila! To use, add an air-dry sample of
(whatever) to the well, cover with liquid nitrogen and let it steam
and bubble for a couple of minutes. Take a new razor blade, mount it
into the handle and secure it with the screw. Holding it vertically,
press down on your sample against the brass plate in the bottom of
the well; you will hear a sharp "crack" to let you know that you
have cut through the sample.

It's not elegant, but it works. We used it for all sorts of natural
fibers, and I expect it could be used for cross-sectioning
synthetics as well. You have various options for mounting the fibers
for examination, of course.

Terry Conners, Ph.D.
Extension Specialist in Forest Products
Department of Forestry
202 Thomas Poe Cooper Building
University of Kentucky
Lexington, KY 40546-0073
Fax: 859-323-1031

                  Conservation DistList Instance 17:51
                Distributed: Thursday, January 29, 2004
                       Message Id: cdl-17-51-003
Received on Wednesday, 21 January, 2004

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