Hi Alison,

This may not help, but what I believe you are describing, in the most
non-technical manner, is that when the blade is freshly sharpened, the angle
of the blade in the microtome chuck is incorrect.  

For setting such angles, I long ago, created a series of guides that permit
me to adjust the blade angle to fixed angles of choice without guessing.  By
this method, I get the kind of repeatability that extends beyond blade age
or imprecise chuck-angle marks.  That is, I can fix the blade at an angle
that works through many resharpenings, then change that angle with some
precision as the behavior of the blade changes over time.  

When I clean my cryotome, I remove it from the chamber, dismantle (NOT
disassemble) it and rinse the parts with (NOT in!) HOT deionized/distilled
water.  I do the same thing with my ancient AO Spencer rotary microtome.
While I do not recommend disassembly of a microtome unless there is a
serious operational reason to do so, these methods of periodic cleaning have
worked for me for over 25 years.  Follow-up with warm air drying or forced
air drying and lubrication works wonders for such devices.

If the blade has been resharpened many times, the angle of the bevel
progressively increases.  Such old blades can be reshaped to restore the
original wedge angles, BUT in the absence of information concerning the
resharpening process applied to your blades, this is mere conjecture.

By your description, it might appear that I have the problem in reverse, but
in fact, you are describing a process by which you have the blade sharpened,
and when it is returned, you provide a 'final' honing with the microtome,
using ice.

All of this explains why I, long ago, changed to disposable blades for the
cryotome.  The initial expense for the holder can be close to $500 and there
is a continuous cost for blades.  The upside is consistent behavior of the
blade in the chuck.

Finally, I can't think of a circumstance in which a 'dulled' blade has ever
worked better - for ME.

Regards,

Fred Monson

Frederick C. Monson, PhD
Center for Advanced Scientific Imaging
West Chester University
West Chester, Pennsylvania, USA, 19383
610-738-0437
fmonson@wcupa.edu


> ----------
> From: 	alison james
> Sent: 	Thursday, January 10, 2002 11:30 AM
> To: 	histonet@pathology.swmed.edu
> Subject: 	sharp blade??
> 
> i use a cryostat to section my embryos and every so often the blade gets 
> sent out to be sharpened.  when we get the blade back it is SO sharp that 
> the tissue immediately curls before we can get it on a slide.  we do use
> an 
> anti-roll plate.  recently we have been using old embryos or straight
> frozen 
> cryo matrix to dull the blade enough to stop the curling.  this however, 
> takes a while.  does anyone have any suggestions on how to dull the blade 
> once it's freshly sharpened?
> -alison-
> 
> 
> 
> 
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