Hard GMA plastic Re: [Histonet] Plastic sections

[Gayle Callis]

Elizabeth,

Don't adjust the catalyst i.e Benzoyl peroxide - you need to keep that 
concentration the same.  You need to add MORE plasticizer - the nn dimethyl 
aniline - that should soften the plastic or make it more pliable for 
sectioning.  Soaking a GMA block is not recommended, as the fumes or 
getting any of the wetted plastic on you is a toxic problem.  Using a hot 
water bath to flatten sections also causes fume release.  I have several 
colleagues who are totally sensitized to GMA plastic and cannot be in a 
room where GMA fumes exist.   I also suggest wearing safety glasses when 
sectioning any GMA, to prevent a section from flying into the eye on a 
static filled day - a problem one lady encountered.

You could also put your blocks in a moist atmosphere to let them humidify a 
bit and soften the plastic.  This may be easier than trying to adjust the 
plasticizer component.

An alternative to GMA is use Technovits 7100 - another GMA kit which many 
really like.  Histonet archives will have discussion on these kits, and 
also more on softening the polymerized blocks.

Good luck

   At 10:27 AM 4/9/2007, you wrote:
>Hello Histonetters,
>We are having trouble with the JB-4 embedding medium.  No matter how
>carefully we follow instructors provided by the vendor, EMS, our blocks turn
>out to be too hard to section with sharp glass knives.  Should we cut back
>on the catalyst, soak the blocks or switch to a different embedding medium
>altogether?
>Any help you can give me will be much appreciated.
>Liz
>
>Elizabeth Wurdak, PhD
>Biology Department
>Saint John¹s University
>Collegeville, MN 56321
>Tel: (320) 363-3177
>
>
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Gayle Callis HTL, HT, MT(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717