[Histonet] Re: Cooling paraffin blocks with ice

joelle weaver joelleweaver <@t> hotmail.com
Sat Sep 29 18:39:49 CDT 2012

I think what you are referring to is a mention about the practical aspect of providing support (from the microcrystalline structure  of the wax)  to the tissue  during sectioning against shearing effects....and I will add the comment that the physical properties and performance of the paraffin media in doing this job  are partially related to temperature, with increasing hardness and support enhanced by cooling. Of course temperature is not the only factor to be considered ( length of the backbone, resins, plastics and other chemical additives come to mind ), but temperature is the one variable that can be manipulated easily by the histotech at the microtome. True there may be some specimens that would need a different set of factors for optimal sections, but in my experience this is a very small number of specimens for paraffin sections, as compared to those types in which the technique of cooling the blocks is beneficial to high quality sections. I would agree that there is a mechanical aspect, as well as certain physics involved in cutting at the microtome, but I think technique and attention to fine details, definately makes a difference in the final slide quality. Just my *opinion* 
Or did I misunderstand  your post? Was it the actual paraffin chemistry you are asking the group to comment about?  Joelle Weaver MAOM, HTL (ASCP) QIHC
 > From: carl.hobbs <@t> kcl.ac.uk
> To: histonet <@t> lists.utsouthwestern.edu
> Date: Sat, 29 Sep 2012 17:23:29 +0000
> Subject: [Histonet] Re: Cooling paraffin blocks with ice 
> Hmmm....
> Nobody has yet mentioned the rationale behind the need to cool Pwax blocks.
> Sure, it makes sectioning easier but....not always.
> Never forget the "huff"!
> Let's get back down to microtomy basics, so newbies have an appreciation that sectioning is a mechanical process, as well as an "art-form"?
> Sure, applies to cryostat, Pwax,vibratome.....
> Curious Carl
> Carl Hobbs
> Histology Manager
> Wolfson CARD
> School of Biomedical Sciences
> Kings College London
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> SE1 1UL
> Tel: 020 78486813
> Fax: 020 78486816
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