Re: [Histonet] carbowax

From:"Bryan Hewlett"


Why does the lab director think you need a higher melting point wax?
If a higher melting point is really necessary, buy a paraffin wax with one.
Substitution of Carbowax for this purpose only, will lead to nothing but 
endless frustration and heartbreak for the techs!
Yes, it is water soluble!!!  Blocks will have to be stored desiccated or 
coated with paraffin wax.
Sectioning in conditions of high humidity can be a real challenge.
Floating out can be a total beast, don't use water since the violent 
diffusion currents will disrupt the sections.
Addition of soap or up to 20% PEG 900 can minimize this, but trust me it's 
still a beast!

Carbowax has a few special uses, it avoids the use of dehydration and 
clearing solvents and results in less shrinkage.
It is definitely not intended for routine use.


----- Original Message ----- 
From: "Erin Wrona" 
Sent: Tuesday, January 10, 2006 7:52 PM
Subject: [Histonet] carbowax

> Hi all,
>  Our lab director wants us to try using carbowax polyethylene glycol as an 
> embedding medium because it has a slightly higher melting point than our 
> paraffin. I have never used it other than in formulations for frozen 
> sections, in which case it is water soluble.  One of the other techs here 
> thinks that it is always water soluble.  Does anyone know for sure?
>  The specifics are:  ems product #19770, PEG 8000 flakes, melting point 
> 60-63 degrees.
>  Thanks in advance,
>  Erin Wrona
>  San Francisco, CA
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