[Histonet] paraffin problem

Gayle Callis gcallis <@t> montana.edu
Thu Dec 7 09:31:00 CST 2006

Stir your paraffin BEFORE you embed, a cheap kitchen spatula works for 
us.   Paraffins contain plastic polymers and other additives that settle 
out when paraffin is melted.  Redistribution of additives will help 
sectioning and get rid of some funky "grit".    We don't use RA paraffins, 
but have noticed this with another brand IF we fail to stir before 
embedding.   Clean your embedding paraffin reservoir regularly.

During processing, the agitation keeps paraffin stirred up.   At 07:46 AM 
12/7/2006, you wrote:
>Lately we are experiencing a problem with our paraffin blocks.  We use
>Richard Allen Type 9 and Type 1.   The tissue doesn't seem to ribbon
>very well and at times the sections have some small striations, almost
>like knife lines.  We have checked the disposable knives and have
>eliminated that variable.  We use a recycled clearing agent but have
>eliminated that also by using fresh chemicals.  We have several tissue
>processors and there is a possibility that the problem could be a
>processor issue however the majority of us think that it is a paraffin
>problem.  We do not see any "grit" in the paraffins.  We are thinking of
>trying a different paraffin and wondered if anyone has switched to one
>of the newer paraffins that work great.  Obviously I can get as many
>samples as I would like but want to see if anyone has any suggestions or
>ideas that would help us eliminate some of the steps of the process.
>Jim Vickroy
>Technical Supervisor - Surgical and Autopsy Pathology
>Memorial Medical Center
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Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367
406 994-4303 (FAX)

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