Summary of Responses: Polypropylene Sockets

Summary of Responses: Polypropylene Sockets

Nicolas R Vogel

1/27/2000

Here is my original post, followed by the responses. Names have been
withheld, as I neglected to ask for permission to use them in a summary
post.

Thanks to all who contributed! We will try these suggestions.


Nicolas Vogel



Greetings!
>I work at a facility that has experienced occasional problems with
>blister-forming bk polypro sockets.
>The difficulty lies in the use of a nylon over the puff liner over the
>cast before pulling the plastic. Amputalc has been copiously rubbed over
>the nylonned-cast , but the nylon occasionally sticks to parts of the
>polypro and can't be removed. Are there any suggestions or other
methods of using polypro
>over a cast with liner?
>
>Thanks in advance for your input.
>
>Nicolas Vogel






Try filling the socket with muriatic acid it will eat out the nylon over
a
weekend. Be careful of it though, nasty stuff!




Dear Nicolas,

We use the same technique, but also use a high quality silicone spray
made by CRC, this usually results in the nylon stocking coming away from
the socket easily. You can use both spray and talc. Depending on the
density of your liner, this may solve the problem. If not, try using a
pva bag - the ones you use for lamination - between the liner and the
nylon stocking.


You might try using either a PVA bag as a seperator or a latex balloon
which
I beleive is available through Daw Industries and Cascade Orthopedic
Supply
Good Luck


Hello...I had tried for a couple of years and every way I could think of
to
eliminate this problem. the only reliable answer I found was to cast the
soft insert and the form the polypro over a plaster/nylon model. It
takes
more time, materials and effort, but it never failed! Good luck.


You will find that the stocking sticks only on those molds that are bone
dry.
 I had similar experiences many years ago when pulling plastic over
bone-dry
molds. My conclusion (after testing to see if I could reproduce the
phenomenan at will...and I could...) was that trace water vapor from the
mold
acts to not allow the molten plastic to literally melt the nylon threads
into
itself. Whether or not this is accurate in what mechanically happens or
not
(I'm sure some genius will set me straight...), I can tell you that
I've
never had a problem with hosiery sticking to my polypro since. I am an
advocate of drying the mold, however, since excessively wet molds produce

poor pulls as well. Just don't let them get bone-dry.
Good luck!



Place the liner on the model......
Place a pva barrier over the liner, (either stretching a one piece sheet,
or
the use of a ready made bag, and tie off the distal end.)
Blister form or drape the plastic over this setup. The plastic will not
stick, and the inside surface will be smooth.



Hi there,

We have had good success saturating the nylon in silicone oil. Fillauer
has a
good quality silicone oil and so have others.




Make no effort to remove or separate the nylon from the plastic. In fact
heat the plastic well enough to be sure that the entire nylon sticks.
Covering the puff liner with a PVA bag will help assure that the interior
of
the socket is smooth with the nylon in place.




Nicholas
We typically drape mold with a posterior seam for preparatory sockets.
Try quenching the molded polypro in a bucket of water immediately after
molding. This cools the plastic rapidly and minimizes the effects of
heat
on the liner, and also produces a glossy finish. I don't know if there
are
any undesirable effects on the brittleness/toughness characteristics of
the polypro, but to date we have had no problems.
Let me know how it goes.







Nicholas,

Try wrap-casting over the liner then pulling the polyprop over the bare
cast.
The method you are using presents several problems. The first is that
pulling
400 degree plastic over a soft liner that forms at 250 degrees will
ultimately cause shrinkage and compression of the soft interface
resulting in
an excessively tight fit. The wrap cast is an extra step but will result
in
less problems.



I have heard of something called French Talc from Blatchford/Endolite
North
America but I have never used it. It is supposed to solve that problem.
Also I have heard some folks use water. That is they soak the nylons
before
forming over them. But, again I have never tried this method either.
Too
Chicken I guess.






Try silicone spray or liquid over the nylon. Our you overheating you
plastic?

 Good Luck



Nicholas, at our facilities we typically pull a poly ethylne liner over
our
pelite or MD liner then pull poly pro over that. We have very few
incidents
of nylons sticking to the poly pro. In those cases where I don't use a
poly
eth liner I blow air over the inner surface of the plastic until I can
see it
glaze over. Once it's glazed over the nylon won't stick. Also, we dip
the
entire nylon in cornstarch prior to putting it on the model. The down
side
to glazing is it makes it more difficult to get a consistant thickness.
If
you have any more questions let me know.



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