RE: Wood sectioning with Carbowax

From:"Monson, Frederick C."

	Well, Mercy, you have certainly come to the right place for
consideration, sympathy, and....Oh! What is that M word?

	This all works when you have a SHORT section (like 5-7mm) of the rod
they send you.  If your problem involves adhesion of an impregnated block of
cherry to a non-impregnated block of pine, then the solution is easy.  Get a
block of maple that is 2X larger in cross-section than the pieces of cherry
and cross-hatch it with a saw.  Drill some very small 1/2" deep holes in the
cross-hatched face of the maple block (about 8 that cover the area of the
cherry ought to do it) and cement some pins with the heads removed and the
points exposed about 1/32-1/16th (or whatever length is appropriate) inch
above the surface of the cross-hatching.  Once the cement hardens, you can
mount the miscreant slice of cherry using the pin points to hold the little
bugger against the lateral force of sectioning and some harder PEG
(polyethylene glycol 800 or more) to seal the impregnated cherry to the
cross-hatched maple.  

	To section the piece you have been given without cutting it into
shorter segments, you must use a chuck of some sort that will accept the
majority of the length while you expose a little to the sectioning blade.
The old AO Spencer black-body rotary microtomes had a 2cm (at least) throat
for the specimen at the end of the specimen bar.  There were metal inserts
that could be added to these to accommodate specimen blocks of various
diameters and cross sections.  You may not need to attach the cherry until
you have sectioned quite a way through the plug.  If there is no room for
that on your microtome and you cannot find one that will do, then there is
another costly possibility.

	You cannot hold something that long and expect the knife to pass
across its face evenly without disturbing the orientation of the object.
You would get the same problem with sectioning a piece of bone that stuck
out so far.

	One more piece of advice, if you will.  The sectioning of hard
materials USED to be much easier when the added stability and ANGULAR KNIFE
of a sledge microtome were applied to the problem of taking sections.
Indeed, some of those also had vice mounts. 

	Finally, If you are willing to soften the wood, then how about using
glycol methacrylate for an embedment.  No alcohol, No xylene, Just a graded
series of GMA's until you add a final polymerizing aliquot.  If you can cut
the plug, then even this becomes more plausible.  

Every sectioning problem has a solution and an artist in whose hands that
solution works.  Never seen a failure except when both are absent.
Hope any of this helps,

Fred Monson
> ----------
> From:
> Sent: 	Monday, February 25, 2002 2:19 PM
> To:
> Subject: 	Wood sectioning with Carbowax
> Hello everyone...
> I'm new to this list, but already I have found it very useful!  I have a 
> couple problems that I would like to pose a question to the arena of 
> experts.  I am working with cherry wood sections and infiltrating them
> with 
> Carbowax instead of paraffin.  However, I am having a heck of a time
> trying 
> to get the sections to (1) stick to the wood block....I am so frustrated 
> that I want to just nail it to the block, and (2) trying to get sections 
> that don't crumble.  I think the answer to my 2nd problem is that I need
> to 
> get the carbowax to infiltrate better, but how can I soften the extrememly
> dense, hard wood?  Any helpful hints on getting the sample to stick to the
> block?  They are about <1 cm in diameter, and about 2-3 cm long. 
> Thank you in advance for your help!
> Mercy Olmstead
> Michigan State University

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