Due to the complexity of this prop, full instructions with detailed illustrations
are available in the
DC Prop Book,
which is available in the
DC
Prop Shop.
This project is going to describe how to mold and cast your own gargoyles,
but the same information can be used to create a mold for any prop.
My only suggestion is that when you are designing a prop, keep in
mind that the mold itself will only stretch so far before it rips,
so try and keep the deep caverns and undercuts to a minimum.
The use of an armature will significantly reduce the cost and weight
of your prop, as well as give you a basic form for the creation of
your prop. You can also use an armature itself as a prop.
There are many commercial bought armatures that you can purchase,
but I recommend building one for your specific application. You have
a basic idea of what you want the finished product will look like,
so a custom armature is almost always the only way to go.
The first step to building an armature is to mold a basic form out
of chicken wire that is approx. 1 to 2 inches smaller then your finished
product . Once you have the armature constructed, you are ready to
fill it with "Great Stuff" expandable foam. I recommend first placing
the armature on a sheet of polyethylene to avoid the foam, clay, urethane
and fiberglass from sealing itself to the work area. When you purchase
polyethylene, be sure to buy the smooth surfaced type. Once your armature
is on the polyethylene, you are ready to start filling it with foam.
Start from the bottom and work your way up. Use 1 can at a time and
allow the first coat of foam to setup before trying to apply the next
coat. Also if you do not give the foam a significant time to dry,
the applications you add above the first will force the foam to compress
and you will have to use additional foam and run the risk of the bottom
coats not drying.
Once the armature is completely filled with foam and it's fully dried,
you are ready to begin shaping the form. To do so I suggest first
cutting off the large segments of extra foam with a razor blade, then
go in with a small disc grinder or a roto-zip with a course sandpaper
disc. Before you begin to sand the foam be sure to protect yourself.
Use a particle respirator, safety glasses that seal onto your face
and proper clothing to protect your skin from the foam particles.
Now begin grinding your armature down until you achieve the basic
form you need to work with.
Once the form is complete you are now ready to begin applying clay.
I recommend using Monster Makers oil based clay. It is by far the
best clay I have ever worked with. To soften the clay I suggest you
purchase a heating pad with a removable cover. Now remove the cover
and expose the plastic sheet. Lay your strips of clay directly to
this sheet and allow the clay to warm up. This warming process will
make your job a lot easier.
Once you have a good foundation to your armature you are ready to
start sculpting. Keep in mind that the mold you are going to be making
is a 2-part mold, so keep the form as simple as possible, while still
achieving maximum detail.
Once your model is completely finished, it is time to cut off the
parts that will not work with a 2 part mold. In the case of these
gargoyles, I had to cut off the wings, teeth and ears. Once the parts
are removed and you have a simple form you are ready to apply a minimum
of 3 coats of Krylon clear coat. This will seal the porous clay as
well as allow the clay to hold together when you remove it from the
female mold. Once the clear coat is dry, you are now ready to begin
making the mold.
To make the mold you will first need to build a retaining wall that
will serve as the wall between the 2 halves of your mold. To do so,
take pieces of your water based clay and cut them into strips that
are approximately 1" thick by the length and width of the clay (should
be approx. 8" square). Now cut those 8" strips in half and begin using
the strips to build a wall up and over the sides of your model. Now
once your main wall is built, you will need to go over the edge that
is in contact with the model with a small stiff bristled paintbrush
to smooth out the gaps. First dip the brush in water, then slowly
go over every inch of the walls contact point to make sure that you
have a good seal (on the side you are planning on molding first).
Once that is done, you will need to spray the model and the retaining
wall with a couple of coats of Synair's mold release spray and once
that is dry, you are ready to begin applying the S333 urethane rubber.
I strongly recommend that you use a squirrel mixer to mix the 2 parts.
It doesn't seem necessary, but believe me it will be the best $10.00
you have ever spent. The squirrel mixer will hook up to your drill
and take all the work out of mixing the S333.
Now that you are ready to begin applying the urethane mix up an ounce
or two of each part in a polyethylene cup. If you cant find these
types of cups locally, I recommend ordering them from Tap Plastics
website. The cups will hold up to abuse as well as give you exact
measurements and ease of cleanup (nothing sticks to them). Once you
have equal portions of each part of the S333 stir them until you are
sure that both parts are well mixed. Also scrape the bottom and sides
constantly to avoid having any urethane that will not dry. Also when
you are running low, I strongly recommend making another batch instead
of scraping the bottom and sides of the cup.
Once the urethane is well mixed, apply a thin coat (approx. 1/8" to
the side you are working on as well as the retaining wall). Allow
this to dry overnight. hat the first coat is dry, begin cutting strips
of fiberglass cloth to lay between the first and second coat of urethane.
Doing so will greatly improve the strength of the mold and hopefully
prevent you from tearing the mold while removing it from the model
or finished product.
Once you have enough strips to completely cover the mold, you are
ready to mix up another batch of urethane. Once again only make a
small batch. Once the mixture is completely mixed, apply a thin coat
to the first coat, than apply the strips of fiberglass cloth. Press
them lightly into the urethane so then become fully saturated.
Once they are fully saturated, cover them with the rest of your batch
of urethane. As soon as this coat is applied, begin mixing another
batch of urethane. This time you can make as much as you think you
can apply evenly in about 10 minutes (depending on the outside temperature).
Once mixed, apply it to the mold. You may also wish to add more fiberglass
cloth if you wish, especially in areas that you believe will have
a tendency to rip. In the gargoyles case the area around the fingers,
knees and inner elbows. The thickness of the S333 should be about
1/2"-1" thick by the time your finished building it up.
The second you are done applying the urethane, you will want to put
on a pair of latex gloves and spread baby oil onto the outside of
the mold and smooth out the surface. This will allow you to make a
hard fiberglass shell, without having to worry about the fiberglass
sticking to any ridges. Wipe away any excess after your done smoothing
it out, and allow the mold to dry for a minimum of 24 hours.
You should now have half of your mold complete. You will now need
to do the same as above to the second side. First remove the clay
retaining wall, than spray the front of the model with a couple of
coats of mold release. I also highly recommend coating the dried urethane
retaining wall with a thick coat of mold release wax, than spray it
with a couple coats of release spray. You need to be extremely careful
when you are applying urethane to urethane. They really like each
other, so if they come into contact, I assure you that you will not
be able to get them apart.
Once you have applied the wax and the mold release spray, repeat all
of the steps above. Your mold should now be just about complete. Our
last step will be to create a sturdy shell, so the mold will keep
its shape prior to it being filled. To do so you will first need to
cut a bunch of strips of fiberglass cloth. Once those are done, cover
the outside of the mold with a coat of mold release wax. Before you
work with fiberglass resin, take the proper precautions and wear the
proper respirator, glasses, and gloves as well as take special care
when handling the fiberglass cloth. The cloth is made up of fibers
that are very irritating to the skin. Also use fiberglass in a very
well ventilated area, I'd probably be a lot smarter today if I took
my own advice. Once your all suited up and your materials are all
within reach mix up a couple of ounces of fiberglass and begin applying
the fiberglass resin to the mold with a cheap and disposable brush.
Apply the strips of cloth evenly around the mold and saturate each
piece with resin. The cloth will turn almost clear when properly saturated
and will have a much higher tensile strength.
Once the resin is hard, repeat the steps until you have a shell that's
about a 1/8" thick. Also pay a lot of attention to the retaining walls,
since this is where you will be bolting the walls together, but be
sure to keep your fiberglass away from the 2 dividing walls or once
again you'll have a huge mess on your hands. Once the shell is to
your satisfaction let the fiberglass completely dry overnight.
Our mold is now complete, but before you go ripping it apart I suggest
drilling holes through the retaining walls, so that when you bolt
the two sides together, you wont have to worry about lining them up.
Once the holes are drilled, remove the fiberglass shells and carefully
peel the urethane cast away from the model. It should come out pretty
easily and if not you may want to fire compressed air into the tough
spots to break the mold away from the model. Hopefully you are able
to get the 2 halves apart fairly easily and you are happy with how
your female mold looks and works. Now you will cast your first product.
The first thing you will want to do is remove any of the small pieces
of clay that may be still inside the mold. Also look for pieces of
the clear urethane you sprayed on the model since that may have also
stuck to the mold.
Once your mold is clean we are ready to coat the inside with mold
release. I have tried many types of mold release and the ones that
I have had the best luck with were a mixture of mold release paste
wax and a thin coat of silicon mold release spray. To add the mold
release, apply the paste wax to the insides of the cast, then allow
it to dry for about 20 minutes.
Once the paste has set up, spray an even coat of the silicon spray
across the entire mold and across the retaining walls. Avoid saturating
the mold and if puddles form, pour them out before adding your casting
material.
*When purchasing silicon release spray pay attention to how fine the
spray is. Some silicon spray that you purchase from hardware stores
spray extremely thick so if you choose to use these spray them into
a "Preval" sprayer, then spray the Preval mister into the mold halves.
Preval sprayers are a compressed air canister that can be screwed
into the supplied glass jar. They work great for just about any application
and are fairly priced and are carried by most hardware stores.
Now that the 2 halves of the female mold are ready to go, you can
begin mixing the Pour-A-Kast in small amounts. Pour it into one of
the mold halves and swish it around to achieve an even coverage. Repeat
this step on the other half of the mold, then once both halves are
just about done you can bolt the two halves together and apply a final
coat of pour-a-kast to the seam.
If you are planning on mounting lights in the eyes, and having smoke
bellow from the gargoyles mouth, you may want to run a piece of 3/4"
vinyl tubing from the mouth and out the base, as well as a piece of
1" PVC pipe from between the eyes and out the base. This will save
you a lot of time, as well as the hassle of having to dig out the
foam. You should now have a rigid shell for your model, but were not
done yet. Next you will need to fill the mold with the expandable
foam. This will dramatically increase the strength and durability.
To do this you will want to have the mold inverted so the foam will
pour into the deepest parts of the mold and rise upwards. Mix the
foam in small batches and do small pours until the model is completely
filled. You may want to have your sheet of polyethylene ready to stop
the foam from overflowing. Your model is now completely done. Wait
the required amount of drying time then unbolt the 2 halves, remove
the fiberglass shell and carefully peal away the urethane exposing
your finished piece.
You will most likely have to do some minor sanding to remove the line
from the retaining wall, but it usually isn't a big deal. Well unless
you mismatched the molds, but you would have already realized you
had a problem on your hands, when the foam and pour-a-kast started
spilling onto the floor.
Now you are ready to do the mold for each wing, the teeth and each
ear. The teeth and ears are small so I don't recommend using a 2 part
mold unless there are a lot of undercuts and also you can skip the
fiberglass shell on these for the same reason. To make a mold for
the wings, repeat the steps you did for the main mold. After you cast
the teeth, ears and wings you are ready to glue them to the body.
Before any gluing or painting takes place you must first wash the
silicon off of the finished piece. Just as the urethane wouldn't stick
to the silicon, neither will the paint or glue. To date, the best
solution for cleaning these is a solution of mild laundry detergent
and orange hand cleaner, mixed in a bucket of water. Scrub every inch
of these then hose them off and leave them out to dry. Once they are
clean you are ready to glue on the parts. I suggest using 90 second
2 part epoxy so you have a strong bond, but you don't have to sit
there holding the parts for hours while they dry. Now that the glue
is dry, take silicon caulk and seal any gaps or spaces that the glue
missed. You may not have any gaps if your molds fit together perfectly,
but if you do its no big deal, you just have to fill them.
Once the silicon is dry your ready to paint. First apply a couple
of coats of primer, then when that is dry begin painting with the
granite paint. Remember to seal the granite paint with outdoor varathane
to protect it from the elements.
Now that your gargoyles are done, your ready to go display them. I
don't recommend leaving them out overnight though. You may have some
really jealous neighbors.