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Molding Organics


#1

Hi,

for those of you that have molded organic materials, could anyone
recommend a process? Im looking to mold some buds off of a plant but
i would like to retain there current form (before they dry out) so
im looking for a liquid silicone molding material, that doesn’t need
to be vibrated on a table ( i don’t have one ) or any suggestion in
general. I just seems like a lot more of a hassle to just send
everything to my casting co. if i could just get some waxes from
what i have then i could send them something decent. :wink:

mackenize


#2

Hi Heather

I do quite a bit of this sort of thing, and I’ve found that painting
on the first layer or two of rubber lets me avoid air bubbles,
without having to use vacuum or vibration. The two-part silicone is
thin enough that it doesn’t easily allow bubbles to form as it drips
off the model, leaving a thin skin. I typically set a small piece up
on a wax sprue attached to a piece of plywood. Once I’ve got the
surface covered and it has set up (allow 24 hours for this) I
surround the piece with a piece of tubing waxed down to the board, a
clay dam, or whatever is handy, and pour in renough rubber to fill
the volume surrounding the piece. When that sets up I cut it out
with a zig-zag stroke to avoid seam misalignment. For hollow waxes
or single-sided ones, I pour microcrystaline wax in, let it set a
while, and pour it out.

There are lots of different formulations of silicone rubber
available; I usually use a tin-soap catalyzed type (#1621) which is
available from my local sculpture-materials supplier Douglas and
Sturgess (www.artstuf.com). The important things to remember about
it are to weigh it carefully (you need to insure that the catalyst is
10% or 5% by weight, depending on the one you’re using); to mix it
thoroughly; and to transfer the mixed product into a separate clean
container and mix again, to avoid leaving incompletely catalyzed
portions which will remain sticky. There’s more about
rubber molding on my site, and more suppliers listed, under
alt.sculpture FAQs.

Andrew Werby
www.unitedartworks.com