page describes the process of forming a six piece mold from the
plug which was constructed earlier.
planning the seams as follows.
Part 1 will be mouth area.
Part 2 will be the chest and programming area.
Part 3 will be the top dome.
Part 4 will be the bottom dome.
Parts 5&6 will be the left and right tube sections.
The first step is to prepare the plug to allow release of our mold.
First apply and polished 3 separate coats of release wax.
Then after waiting 6-8 hours apply and polish two more coats.
shot of the polished plug
how the pole allows access to all sides of the torso without touching
waxing we apply a coat of PVA release agent. This stuff is
best sprayed on in three thin coats. It forms a very thin
sheet that separates the plug from the mold. Once the plug
is released from the mold the PVA can be washed off. Let the
PVA dry between coats.
The Mold Seams
We must create seam lines so that each separate mold piece can be
pulled. I will align my seams on the raised trim areas, this
will allow any flashing on the final piece to be easily sanded off.
I will start with the moutharea. Then the chest and programming
area. Domes and finally the two tube sections.
We use clay to create a "dam" around the area to be done.
Once done the clay is removed and release agent is again applied.
We will make "keys" or small indentations in the clay
dam. These will ensure good alignment of the separate mold
sections when we reassemble it.
by Step For The Mouth Area
I'll show step by step how to do the first portion, the other portions
will be similar.
I created a dam around the mouth portion using clay. Note
the small "key" holes in the clay. The clay has
been given a coating of PVA release agent.
step is too apply the tooling gel coat. This should give our
mold a smooth, hard and durable surface. The tooling coat
will be 20-25 mils thick. The first mat layer should be added
with 1.5 - 5 hours to stabilize the tooling gel coat. After
that cools, we'll build up using 8-10 layers of 1.5oz mat.
the black tooling gelcoat has been applied. Also note that
a fillet of resin, cabosil (thickener) and 1/4" chop strand
has been used to round out the sharp corners. This will allow
use to lay up mat without trapping air bubbles in the corners.
we can lay-up the mat. I'll do only two layers for now.
After all sections have two layers I'll go back and add more.
the clay and we're ready to start the next portion.
Note how this area will mate up against the first area. We
continue this process until all the areas are done (two layers of
a shot of chest area dam
we've covered all areas except the bottom dome
a shot of the finished mold, plug still in it
we've covered all portions of the mold. Next we use 8-10 layers
to build up the mold thickness to ~3/8 - 1/2 inch thick. This
makes a very strong mold.
we drill holes for the bolts that will hold the portions together
when we are ready to cast a torso. Finally we trim the edges.
for the moment of truth, will the mold come off the plug? It does!
I am amazed how easily. The mold surface is a high gloss too!
If you look close at the following pictures you can see the very
thin mold release film. (It's on the dull looking areas.)
are the parts as they come off the plug
release agent washes right off. Here the mold family sit and
watch their favorite Lost In Space episode, "Wreck of the Robot".
a shot of all the pieces reassembled, except for the bottom
mold is finished! Next step is to give this baby about six
coats of wax, then it'll finally be time to cast our torso!