A small layer will not polymerized if I use certain types of plastic
vials.  If your tissue  is not labeled, you can put the the vial under a
UV light to harden up the "gooey" layer on the top.  It should only take
about an hour or so.

Karen Bowden
University of CA, San Diego
Dept. of Orthopedics
La Jolla, CA

"Renton, Lousie, Mrs" wrote:

> Hi there,
> this is a question for all the resin users.
> I have started using polypropylene pill vials (the sort with a snap-on
> lid)  as moulds for my resin blocks (MMA). I have subsequently
> found 2 things happening:
> 1. If the lid is snappped on securely I get the "champagne effect"
> with millions of bubbles frozen for all eternity in the resin.(unusable
> blocks - start again)
> 2. If the lid is left with a little gap or a pin hole or 2 - the resin
> polymerises fantastically without bubbles, but a layer of gooey stuff
> remains at the air/resin interface - up to 0.5cm thick
> Is this normal?
> How do I get the gooey stuff to set? - heat it? cool it? wait for
> another day?
> Do I just scrape it off and pretend it didn't happen?
> BTW - the moulds are left in an incubator overnight at 24 degC
> leaving them o/n at RT results in VERY slow polymerization
> (?airconditioning)
>
> All comments welcome
>
> Louise Renton
> Bone research unit
> MRC
> Johannesburg
> South Africa