Re: cleaning knives, Prefer unclean

<< Previous Message | Next Message >>
From:Jeff Silverman <>
To:Gayle Callis <>
Date:Wed, 07 Apr 1999 18:09:06 -0400
Content-Type:text/plain; charset=ISO-8859-1

Clean blades?? Never heard of such a thing. My AccuEdge low profile are at
first hypersharp sometimes, causing rolling of the first few sections but
facing something soft or waiting for a few sections gets the ribbons
flowing. Also, gentle hot breath (like fogging a mirror) on the block as
you cut never fails to form a ribbon. Looks dumb but it works. Also, I
never knew of the invincibility of 1% periodic acid. I prefer to stain the
slides dropwise on the counter using fresh periodic and Schiff each time.
Of course, in my dinky little hospital I never have to stain more than five
at once anyway. 
Jeff Silverman 

> From: Gayle Callis <>
> To:
> Subject: cleaning knives, more comments
> Date: Wednesday, April 07, 1999 3:40 PM
> I have found this discussion interesting.  I wonder what the vendors have
> to say about this?  Also, if they give the advice, is it because they
> have direct experience with "knife cleaning" and daily sectioning, or is
> this blanket concrete evidence advice?  
> I find comments about a knife being too sharp, you have to dull it an
> interesting comment.  I have never found a knife too sharp for my
> tastes/usage.  I section routinely at 2 um, with an "unclean" blade, 
> without any problems (Accuedge, high profile, and have used the low and
> a whole array of vendor manufactured blades.  Also, if you clean knives
> paraffin sections and not frozens, why?  If oil is the problem, would
> be a difference?  And if it is a sharpness problem why would you need
> duller blades for paraffin vs the frozens? 
> I always felt (what is often construed as too sharp a blade??) that the
> differences in knife angles, even between lots of knives, was more of 
> a difference, rather than a knife that is too sharp.  If I have problems
> cutting a block, with a brand new knife, it often is a slight tweak of
> holder to fine adjust that takes care of the problem.  Other factors are
> paraffin, tissue, and how it was processed.  I also found that a section
> not forming correctly on a new blade was also linked to a truly square
> edge on the block (un- bless those rounded corners on embedding molds!,
> love the peel away molds, square corners!)  I often reshape rounded 
> corners, and all goes well on a brand unclean blade.
> so if cleaning is of prime importance, it would be to remove oil, and
> the sharper the blade, the better I like it.  After all, I don't dull my
> glass knives before use, and like my disposables to approximate these
> blades as much as possible.  I did go through a time of cleaning
> but overall found it didn't make any difference, and actually preferred
> "unclean"  Could that have been damage to the coating of the edge,
> and whatever else has been used?  That is a good point.  
> I have seen blades with too much oil gunk, wondered about those, but
> never have had a section fall off from oil contamination of slide, 
> Dirty slides - yes or mungey fingerprints on slide surface - sections
> like oily skin.  One study required NO fat carryover from slide to slide,
> that did require cleaning a knife between blocks, and everything else in
> vicinity of blade inside a cryostat.  
> Sorry for the tirade, but have found this whole discussion educational,
> At the risk of being a very "dull" person, I remain in the "unclean"
> Gayle Callis

<< Previous Message | Next Message >>