There are ways to slow done rapid polymerization.  Cold temperatures is
one.  When mixing your embedding mixture, keep it on crushed ice while you
embed,  also put your embedding molds on a block of ice.  JB-4 also had
this problem.  You should be able to adjust the accelerator, add less to
slow down the reaction. This was a way to slow down JB4, particularly very
fresh solutions.  

Also, never mix up a huge batch of what you need for embedding, 25 mls at a
time was optimal for JB4 GMA.  Never use a vacuum to infiltrate with GMA,
exclusion of air promotes polymerization, have had that happen. Infiltrate
in a refrig overnight, to permit good total infiltration.  The tissue
should be transluscent and settle to bottom of the vial.

You can also make up your own GMA mixtures, cheaper, and you can adjust for
hardness, etc.  Patsy Ruegg had a publication on this, did her own mixtures
with great success. Kits tend to be pricey.
  

At 02:41 PM 1/7/02 -0500, you wrote:
>Hi Histonetters,
>
>         We do a lot of plastic work as we're a research Histology Lab.  We 
>used to use Leica's Historesin with great success.  JB-4 did not pick up 
>the stains as well and had a tendency to yellow so Historesin was the resin 
>we used.  Due to new shipping regulations, Leica is no longer importing it 
>into the USA from Germany as the shipping is too costly.  Technovit 7100 is 
>supposed to be virtually identical but we're having problems with it.  It 
>sets too quickly and it doesn't seem like the resin infiltrates 
>properly.  Our blocks are still a little soft, despite repeated baking and 
>there are holes in the tissue.  Is anyone else having problems and have 
>they come up with a solution or a better resin?
>
>Lesley
>
>
>
>Lesley S. Bechtold
>Supervisor, Biological Imaging
>The Jackson Laboratory
>600 Main St.
>Bar Harbor, ME 04609
>207-288-6191
>
>
>
>
Gayle Callis
MT,HT,HTL(ASCP)
Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367
406 994-4303 (FAX)