Monday, April 22, 2024

Vacuum forming flexible thermoplastics over foam carving

mark sethi

Hello all,

I have a fabrication question about how to smoothly pull flexible inner
thermoplastics such as Northvane, Duraflex, Pro-Flex with Silicone, &
Striefyflex over digitally carved foam models. I am using the basic
Fillauer foam blanks.

I have tried many technics pulling over a foam model and the inside of the
cup has come out extremely textured. I would like the inside of the cup to
be smooth and would appreciate advice on how to make it happen.

Thus far into my trials I have tried the following:

•Variable temperatures from 350 – 400 F on the variations below

•Silicone mold release sprayed directly on the foam

•Two layers of nylon stockinette coated in silicone mold release

•One layer of nylon stockinette followed by a latex casting balloon

•Latex casting balloon coated in silicone mold release

-Vorums pulling instructions on co-poly, polypro

Any nylon/cotton stockinette method just won’t work so far.

Additionally, I have tried to float plaster with and without vermiculite
over the foam and had limited success with that as well. It is possible for
the plaster to stick to the foam, but for the most part the plaster slurry
beads up and does not spread over it smoothly.

I am stuck where I have to duplicate the foam model in plaster and smooth
it to get the finish I want.

Any advice or direction on how to get a smooth finish on the inside of the
cup on par with direct plaster pulls would be greatly appreciated!

Thanks all!

Mark Sethi CP,CPA,CTP



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