- [Instructor] Now that you've got your
accurate mold together, now what?
Well, it depends.
Did your master form leave any dust
or residue inside?
You'll want to clean that mold up.
I sometimes find that using
an inexpensive plastic as my very first pour
tends to grab anything that might've
gotten stuck in the nooks and crannies
For the purpose of this breakdown,
I'll assume a few things.
A, that you're using silicon rubber
as your molding material.
B, that you're using a two-part mold.
And C, that you're using a urethane casting material.
Once you've got a handle on this soft,
pliable mold, and hard plastic casting process,
more layers of steps can be added.
But we have to start at the beginning.
So, with those conditions in mind,
let us begin.
You've got your mold.
It's as clean as you can get it.
And you've let it cure completely.
Step one, prepare your work area.
Cover your work surface with a disposable barrier.
Two, assemble all of your casting material compounds
and unseal them.
Containers can sometimes be sealed shut
with spilled material.
Gather all of your cups, mixing sticks,
measuring cups, and additives, like colorants,
within arm's reach.
Three, if you are using a mold release spray,
spray in a well-ventilated area,
not directly in the space you'll be using
to mix and pour into your mold.
Let the mold release off-gas for a certain
amount of time before using your mold for casting.
The can will have specific instructions
per the mold release.
Four, place your bottom mold piece
into your box for support,
making sure that there's no debris in the mold box,
or trapped air deforming in the silicone.
And then place the upper mold piece on top
of the bottom mold piece,
making sure that any registration blocks
for alignment are lined up properly.
You're going to want to pre-stir
your resin parts with separate,
dedicated mixing sticks in their containers,
making sure to scrape the sides and the bottom.
Materials can sometimes start to separate in storage.
So make sure it's homogenous throughout.
Do not mix up your sticks.
Six, determine how much volume you need
to mix to avoid waste.
If you over-pour the first casting,
note how much material you really needed
to fill that cavity.
A handy tip for measuring amounts.
If you can, using a measuring cup
that has lines along the side helps,
because you can see how much water
the addition of your master form displaces
in the total liquid volume.
If you start out with one liter,
and adding your master form makes the
total volume 1.25 liters, you can then make
a quarter liter of material total,
though I'd mix a little extra, just in case.
Seven, read and comprehend the instructions
on your material packaging.
Measure the specified portion into separate cups.
Take your time doing this,
and double-check that you have the correct
portion amounts in their separate cups.
Eight, once you've determined you have
the right amount of A and B,
pour them into a third cup
and use a third separate mixing stick
to mix them together thoroughly
making sure to scrape the sides and the bottom
of the cup to make sure you're getting
all of the material thoroughly mixed in there.
Larger volumes call for specialty tools.
I'm very fond of my power drill attachment
that turns my drill into a large
bucket material mixer.
Mixing introduces bubbles.
If you have a longer working time on your material,
you can use this to decast the mixture
in a vacuum chamber, pulling the bubbles to
the top of the liquid, and out.
Careful, you could make the container squeeze.
So leave lots of extra room in your cups
for deformation and splash.
Nine, once you've got everything mixed together,
and de-gassed if applicable,
you can begin pouring into your one or more intake ports,
I've illustrated that here with the funnel,
trying to pour a thin stream that will help
release any remaining bubbles through
surface tension into the air
and not remaining into your mold.
Once you're finished pouring your casting material,
it's time to wait.
Ten, once you've waited the specified time
to demold your new cast component,
you can the mold apart to reveal
a solid cast copy of your master part.
You can keep repeating with the same mold
and make multiple copies.
Of note, this little sprue here will need
to be trimmed off of every cast component
because you wanna make sure
you fill it completely.