Fiberglass / Mold release advice requested

[Mark Zivley]

Note: remove the second "hot" in my "reply to" to email directly

I'm working on a project to fabricate a fairing to cover a small
protrusion. I've made a mold (external) that I now want to cover with a
mold release agent and then put fiberglass on top of. Ideally I'd like
to be able to remove the fiberglass from the mold without destroying the
mold. The mold is somewhat delicate in that it is foam covered with a
thin layer of plaster of paris that I sanded smooth. I painted it with
a glossy spray paint to get a smooth surface finish to try to help the
mold release agent be successful. However if the mold release has too
much adhesion I'm concerned that the foam/plaster of paris will come off
with the finished fiberglass piece.

Basically the mold looks like a teardrop shape (cut in 1/2) and I want
to put the glass on top of this, yet get it off the mold once the resin
cures.

Ok, I bought some stuff from Aircraft Spruce called "plastilease 512b"
and I've played around with it just a bit. It seems slippery enough
when it's still damp, but once it dries it appears to stick pretty good.
Masking tape adheres well to the dried plastilease. If the
plastilease came with instructions, I have lost them.

http://www.aircraftspruce.com/catalog/cmpages/mold.php

1. do you put glass/resin on while the plastilease is still wet or is
it intended to dry first?

2. is there a better mold release agent that I can use?

Any additional suggestions welcome.

Thank you,

Mark

[Richard Lamb]

Mark Zivley wrote:
>
> Note: remove the second "hot" in my "reply to" to email directly
>
> I'm working on a project to fabricate a fairing to cover a small
> protrusion. I've made a mold (external) that I now want to cover with a
> mold release agent and then put fiberglass on top of. Ideally I'd like
> to be able to remove the fiberglass from the mold without destroying the
> mold. The mold is somewhat delicate in that it is foam covered with a
> thin layer of plaster of paris that I sanded smooth. I painted it with
> a glossy spray paint to get a smooth surface finish to try to help the
> mold release agent be successful. However if the mold release has too
> much adhesion I'm concerned that the foam/plaster of paris will come off
> with the finished fiberglass piece.
>
> Basically the mold looks like a teardrop shape (cut in 1/2) and I want
> to put the glass on top of this, yet get it off the mold once the resin
> cures.
>
> Ok, I bought some stuff from Aircraft Spruce called "plastilease 512b"
> and I've played around with it just a bit. It seems slippery enough
> when it's still damp, but once it dries it appears to stick pretty good.
> Masking tape adheres well to the dried plastilease. If the
> plastilease came with instructions, I have lost them.
>
> http://www.aircraftspruce.com/catalog/cmpages/mold.php
>
> 1. do you put glass/resin on while the plastilease is still wet or is
> it intended to dry first?
>
> 2. is there a better mold release agent that I can use?
>
> Any additional suggestions welcome.
>
> Thank you,
>
> Mark

Hi Mark,

Sorry, never played with the stuff you are asking about.

But, in general, Elmers glue and/or duct tape make excellent mold
release agents for small parts.

[plasticguy]

> Mark Zivley wrote:
> > Any additional suggestions welcome.
> >
> > Thank you,
> >
> > Mark


Mark.
if you used spray paint to seal the surface, all you
really need to do to get it to release is use many coats of
automoblie paste wax. Put it on, let it dry, buff it by hand with a
rag. Put on about 6 coats, and you'll be fine. The problem with
spray paint is that it is pourous and will absorb was. Thats why you
put on so many coats.

Scott.

[Corky Scott]

On Thu, 1 Apr 2004 08:14:14 -0600, "plasticguy"
> wrote:

>
>> Mark Zivley wrote:
>> > Any additional suggestions welcome.
>> >
>> > Thank you,
>> >
>> > Mark
>
>
>Mark.
>if you used spray paint to seal the surface, all you
>really need to do to get it to release is use many coats of
>automoblie paste wax. Put it on, let it dry, buff it by hand with a
>rag. Put on about 6 coats, and you'll be fine. The problem with
>spray paint is that it is pourous and will absorb was. Thats why you
>put on so many coats.
>
>Scott.

Scott, I was told that too, and applied three layers of a special
paste wax designed for mold release and polished them just like the
directions said.

When it came time to pull the wingtip off the mold (male mold) I
nearly destroyed the mold as the fiberglass had bonded quite nicely to
the waxed surface.

Actually I guess you could say that I DID destroy the mold because it
took another week of filling and sanding and varnishing to get it back
to a ready to use state again.

The next time I tried, I used the wax AND a release agent. The
release agent worked very well although it was a little troublesome to
get on the surface.

Corky Scott

[Nolaminar]

With permission of wife, use her "Pam".
GA

[jls]

"Nolaminar" > wrote in message
...
> With permission of wife, use her "Pam".
> GA

Excellent. I've used it but it's a mess to clean up. Also I've used poly
vinyl alcohol which I think may be the ingredient in Rainex, the stuff which
makes the water bead up and roll off your windshield when it's raining.

[x]

Guys, it's simple. Cast your form out of Jello, lay up your fiberglass over
that, then just eat the Jello.

" jls" > wrote in message
...
>
> "Nolaminar" > wrote in message
> ...
> > With permission of wife, use her "Pam".
> > GA
>
> Excellent. I've used it but it's a mess to clean up. Also I've used
poly
> vinyl alcohol which I think may be the ingredient in Rainex, the stuff
which
> makes the water bead up and roll off your windshield when it's raining.
>
>

[Leon McAtee]

Mark Zivley > wrote in message >...
> Note: remove the second "hot" in my "reply to" to email directly
>
> I'm working on a project to fabricate a fairing to cover a small
> protrusion.
> 2. is there a better mold release agent that I can use?
>
> Any additional suggestions welcome.
>
> Thank you,
>
> Mark

If this is not going to be an item that you will need to bond onto the
plane securely try your choice of silicone spray, WD-40, or Vaseline
mixed with a bit of Naptha. They all work well. I've never had good
luck with PVA - which is probably what you got from AS+S. Next time
skip the paint and use "green soap" on the plaster.
===================
Leon McAtee

[B Lacovara]

Mark,

Lot's of advice so far... and all of it bad. From someone in the composites
industry, there are serious drawbacks with each homebrew "mold release"
material mentioned, except PVA. Find the local FRP materials supplier and get a
can of basic mold release paste wax. It makes no sense to invest all the time
and effort in your project and then try to save $7 by using some doubtful
concoction for mold release.

Bob

[Fred Stewart]

I have been making molds an fiberglass parts for nearly 30 years and have
never had a part stick in the mold. I use a good paste wax to wax up the
mold. After that I use a product called Partall wax. Partall can be found on
the internet or at your local supplier. I live in St. Louis so it is not a
problem. I usually put 2 coats of the partall wax, let dry, and buff off.
Lastly I use Partall #10 which is a liquid spray on application using the
cheapest spray gun you have. Usually 2 coats sometimes 3 will do. It is
cleaned up with warm water. After the partall dries you can apply you
gelcoat and fiberglass. After the part has cured use compressed air if your
part is in tight. But I have never had the fiberglass stick to the mold. I
have made some mighty tight molds but the parts always come out with a
little air and patience. In some recent fenders I drilled 2 holes in the
center of the mold then repaired the holes with modeling clay. The resin
will not stick to the clay. After the part is done I use compressed air to
blow the clay out and loosen the part. The partall can be washed out with
warm water as it disolves easily. I am no means an expert but this is what I
do.

Sincerely

Fred Stewart
http://www.phatfreddies.com
http://www.mini500.com


"B Lacovara" > wrote in message
...
> Mark,
>
> Lot's of advice so far... and all of it bad. From someone in the
composites
> industry, there are serious drawbacks with each homebrew "mold release"
> material mentioned, except PVA. Find the local FRP materials supplier and
get a
> can of basic mold release paste wax. It makes no sense to invest all the
time
> and effort in your project and then try to save $7 by using some doubtful
> concoction for mold release.
>
> Bob

[Evan Carew]

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Ok, I've seen quite a few responses to this posting & have been
wondering about some techniques I saw in the Dayton, OH weak signals
show I went to last year. While there, I saw a demo of mold use where
fiberglass cloth was applied to foam with a vaccuume system & a mold
where a sacrificial membrane was used against the mold in order to
provide a ready to show released part. The demonstrator even went so far
as to spray paint the sacrificial membraine prior to applying the
fiberglass & core material. When the part was extracted, not only did it
look good, BUT IT WAS ALREADY PAINTED!

Does anyone know if this is in use today for larger parts?

Evan Carew
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