automatic coverslipper/dirty slides inquiry

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From:Gayle Callis <>
Date:Thu, 29 Jul 1999 11:32:11 -0600

The message I posted the other day was incomplete and was an inquiry sent
to me by another person with coverglass problems.  I forwarded all 
answers to her, prior today, but have received some calls thinking I was the
one (my fault for not adding more to message!) with clean coverslip 
problems. These are her comments, I, personally, do not have problems
with anyones coverglass, but also do not have her special applications. 

Here is the message again, and please send your replies directly to her 
at (Donna Simmons).  I do not believe she is on Histonet,
but would like the input.  Thanks

Gayle Callis

Message from
	After trying numerous supposedly-precleaned brands of coverglass, I
have been using Richard-Allan coverglass for many years with
satisfactory results.
However, recently [24x50 rec'd in January, 24x60 rec'd in March shipments
of coverglass have been quite dusty-dirty in a peculiar way:
there is a fine, almost powdery dust that doesn't show very clearly
to the naked eye or on Brightfield microscopic illumination, but looks
like a "starry night" on darkfield illumination!  This is a terrible
problem for us, since 80% of our data analysis is done with darkfield
Unlike dust I've encountered in the past, this cannot be removed
with an airjet [or even cleaning with lens paper] while coverslipping.  A
vigorous post cleaning of the dried slides decreases, but doesn't eliminate
the problem on the surface, but the side of the coverglass sealed under
the mountant still shows bright specks on darkfield, even after
thorough drying.   I suspect that the problem could be from glass or silica
dust produced in the 'sand blast technique' used to make some kinds of
frosted end slides.  However, since I have yet to talk with anyone who
actually knows the details of the manufacturing, that's just my best guess
based on past experience.

Richard-Allan admits that they have been having some problems with
coverglass quality recently, even with their 'Signature' highest
quality coverglass used for coverslipping machines.   In fact, the
replacement glass we received this week was the worst of all - some boxes show
much dustiness to the naked eye.  They told me that the original
Richard-Allan was bought out by Sybron [Cybron?] some years ago, and that they
have not been manufacturing their own coverglass for 2-3 years.  Apparently,
Erie Scientific who now makes Richard-Allan coverglass is the almost
exclusive coverglass supplier to all brands sold in America.  One of our
Brazilian postdocs suggests ordering the German coverglass [Kinittel Glaser
brand] she used in her old lab, but her advisor says even that brand is
only adequate, not great.
So, before going on an all-out worldwide search for the perfect
clean coverglass, I thought I'd tap the shared knowledge of the VIR
newsgroup...Any words of wisdom, advice, sources of a better coverglass, etc.
would be gratefully received!   I hope the problem can be solved from the
manufacturer end without a great deal of time and effort on our
part.  But, if Richard-Allan or other American coverglass doesn't improve soon,
we'll be dead in the water on our most important research technique.  I
know you can remove a lot of artefact in Photoshop for publication... but
this too much.

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