Responces to pulling plastic over foam blocks

Responces to pulling plastic over foam blocks

jason friedman

10/4/2002

Thanks to everybody who responded!

Here are the copies of the e-mails that I have received.

Thanks again!

Jason Friedman, C.P.O.
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If you would like, please call our technical expert Paul Spencer, and he'll be happy to provide you with all the information. It's too long to explain via email.

Thanks,

Arica Finnieston
Biosculptor Corporation
T 305-823-8300
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If you are pulling Vivak or similar over a cad/cam
foam block, just pull a PVA bag over it. First pull a
nylon vacuum hose on. The trick is to puncture the
PVA bag with a new/sharp sewing needle. You don't need
too many holes. Space them about 2" away from each
other. I also spray the PVA bag with a light coating
of silicone spray just prior to pulling the vivak. It
works very well as you can push any air bubbles that
form to an area where there is a hole.
After the foam has been scooped out and the bag
removed you will find some very small bumps where the
Vivak pulled into your holes. Just tick these off with
a Ticro cone. Use a propane torch to clean up the
fogging on the vivak caused by the Ticro wheel. You
then get a nice clear check socket.

Hope this helps!

                Scott Madsen
     API Central Fabrication/Paso Robles, CA
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From Tom Whitehurst,CPO

Before you pull the plastic, put one nylon stockinette over the
block, dip the block in water, then pull the plastic. You will not
get any sticking.

Tom
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First of all your foam block should be of good quality (no bubbles enclosed). If there are any bubbles (even under the surface - please check well) fill them up with plaster. Otherwise your vacuum will pull the plastic into the soft spots or concavities.

We do typically apply a stockinette (sewed distally) or a nylon sock.
Over that we apply a PVA sleeve (welded round at the distal end).
Typically this leads to the desired result.
If you work with clear plastics you may see some tiny ridges or lines in the socket wall. Treating them with a torch (carefully - do not overheat) will clean out any of them.

Hope this helps

Wieland Kaphingst CP
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Try using a large latex balloon with a nylon hose under it and one over it sprayed with silicone. We have used this before and it worked well for us. You might try sealing your foam with some kind of sealer.
Robert Carlile, RTPO
Prosthetics Lab Supervisor
Texas Scottish Rite Hospital
Dallas, Tx 75219
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Jason, I put a nylon over it and do it one of two ways...either pva bag it
with a couple holes punched OR wet it completely with just the nylon on it
both work well for me.
craig
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We have found out that the most effective method is to white wash
(very watery mix of plaster) the mold prior to pulling the plastic. Our
findings were that the foam (no matter what the density) gives some what
when the plastic is put onto the mold under vacuum. This in return will
cause the plastic to nonot only stick to the mold but will also cause
the nylon hosiery to stick as well (even if the nylon is treated).

One other method was, after the nylon hosiery is applied to the mold;
spray the mold with armour-all just prior to pulling the plastic.

Good luck
Steve
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Jayson, I have had some luck using a wet nylon hose over the foam mold with PE,
HPP or co-poly. With the clear fitting socket material I didn't have any
problem with forming. I haven't used the foam for forming afo,s or tlso,s but
would think the dame should hold true.
John Stewart, LP, CP
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Yes, we have been on Cad for 3 years in our central fab. use your nylon then
rub silicone oil on it and the check sockets will be crystal clear
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Try pulling a PVA bag over the foam model, we also use latex cones or
casting balloons. Both need perforating with a small needle to allow a bit
of vacuum through.

Steve Hockey
La Trobe University, Australia
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Dear Jason;
Pull a pva bag over the foam carving. Do not cap the distal end as it
facilitate suction. Ever since I tried this method, I had no trouble.
Aman Raj BS.,CPO
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Use several layers of stockinett when a liner is incorporated. If no liner, coat the plug w/ a white wash mixture of plaster and water (paint it on).

Jason Tamalunas, CO
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Jason, on our check sockets I skim coat with plaster and then wet sand to get a smooth finish. This usually prevents plastic from sticking to the foam blank. Take wet, runny, plaster and wipe over the mold with your hand and then use fine grit cloth to smooth after the plaster semidries.I've heard other people pull a pva sheet over the mold and then pull plastic but I've had terrible luck eith bubbles, lumps, etc.
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Try 2-3 Layers of nylon hose & silicon spray.

Rick E. Sevier
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If you want to pull plastic over polyurethane foam without the plastic sticking to the foam or nylon sock put a coating of plaster over the foam. You can use a paint brush and paint a coat of watery plaster over the foam mold.
Buck
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Try using shrink wrap material like used on the covers of video tapes.

-Mike Kogan, CP
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Plaster wash it. No problem
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What type of plastic are you pulling?With some using a vacuum nylon
works great(I like ones that are sold in bulk thru Jim Smith
Sales)however some plastics will pick up an imprint and in some cases
not release vacuum wicks. The Armor All trick John spoke of works well
you can also use Silicone sprays and in some cases baby powder.Another
that I have used in past is to use PVA as a seperator,but again it
depends on the plastic you are using.
Thanks for writing,
Vince
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hey jason, i found that pulling a stockenette(panty-hose) over the
model and then spraying it with a healthy dose of armor-all works
great. i have no problems with it. also, a new trick i found works, if
the model is the right shape for pulling off the mold, i use one of
those dog in-ground screw leash holders. it looks like a big screw. i
screw it into the model, clamp it in the vise, and pull the #%@# out
of it. good luck! franz
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