Benzoyl peroxide must be 99% free of water, I bought it this way from
Aldrich, and stored it in refrigerator. 

You did not say what protocol you were using, more specifics and how you
are doing it would help. 

Lots of reasons for nonpolymerization, high humidity is also a problem.    

Mixtures should not be old, usually make up embedding mixture the day
before use, stirring it overnight. Any mixture should be no more than a
week old so change them faithfully 

If polymerizing at room temperature, it takes a bit of time to get the
polymerization started. Prepolymerized layers help or seem to aid getting
it all started. ALWAYS cover your container, use flat bottomed specimen
containers, Histoplex from Fisher are great.  Evaporation of monomers can
occur BEFORE polymerization, and that is incorrect. 

I never had problems with my mixtures polymerizing (didn't I send some to
you???) By adding prepolymerized PMMA powder (Aldrich High Molecular
Weight) to the infiltration and embedding mixtures, you get excellent
polymerization, and this seems to get things started, having powder added,
plus it avoids the messy monomer washing.  Everything MUST be at room temp,
if you take a solution out of the refrig, warm to room temp before OPENING
a container, that means stock solutions id powdered benzoyl peroxide, or
containers with bone infiltration mixtures, with or without bone in these.
Any kind of water will prevent polymerization also, poor dehydration,
clearing (use xylene in first clearing, then Propar or Clearite 3) the
latter are sensitive to water, and water is the enemy. 

Fisher Monomer, it is excellent, formerly Kodak.  If your bones are small,
you can polymerize in a waterbath 37C, no hotter or bubbles occur, and
NEVER use an oven, instant bubbles, messy, terrible and toxic fumes.   



At 03:59 PM 10/23/01 -0400, you wrote:
>Hello Everyone,
>
>A question about MMA embedding.  Do you need to dessicate the benzoyl
>peroxide before mixing it in with MMA/softener solution?  I'm having trouble
>getting the embedding solution to set up and plasticize, not hardening at
>all,  no reaction taking place.  Could anyone share their procedure with me?
>
>Thanks
>
>Nancy Weber
>Research Associate
>Veterinary Clinical Sciences
>Ohio State University
>
>
>
>
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)