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Shell-Shock molds

Shell-Shock by Smooth-On is one of the best mold-making products on the market. It is ideal for making fast, lightweight, rigid molds for creating silicone appliances and effects (use as a replacement for ‘stone molds').
 Being a Urethane base product, it needs a good mold release.

FuseFX F-201 Pure White is an excellent silicone paint that can be used as a silicone barrier coat / mold release. 
It is highly pigmented and is very flexible under normal use, but when applied as a heavy layer it does become stiffer. It is more of a shore 30A resulting in a perfect medium to create a silicone film coating.

The beauty of the FuseFX F-201 Pure White paint is that it a can be used on oil based AND water based clay, assuming that neither contain sulfur.

Testing the clay for Sulfur or other contaminants:
A quick test is to mix a small batch of paint in a container and apply a little on the clay sculpture and let it cure.
After a couple of hours, the mixed batch in the container should be cured.
Now touch the painted area of the sculpture. If the paint is cured, then the clay is free of contaminants. If the paint is wet and feels sticky, then the clay contains sulfur and cannot be painted with FuseFX.


The technique:
By spraying or airbrushing several coats of F-201 Pure White (3 to 4 coats, or until the piece is a uniform white color), you create a very thin but strong silicone skin over your sculpture. This becomes a barrier between the clay and the Shell-Shock.
Once the Shell-Shock is fully cured, the F-201 Pure White silicone film will make the plastic shell easily removable, creating a perfectly clean mold with every detail intact.
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The piece:
This is a nose prosthesis I sculpted for a cancer patient:
The lifecast was taken with Smooth-On's Body-Double and was cast with NEO plaster.
I used Chavant Y2-Klay for this piece because of its ability to beautifully retain detail.
You will notice a marker line around the clay edge about 1mm away. This is to mark the area where the edge of the clay finishes and will appear through the paint.
Note the soft beige colored clay blocks on the forehead and chin (top and bottom). This will become the area in which you place a screwdriver to pry the mold open.


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The process:
Once the sculpture is complete, it is now ready to be coated with FuseFX F-201 Pure White.

 FuseFX silicone paints can be reduced for spray painting by mixing 1 part paint to 2 parts solvents. Please read the Application Instructions and observe ALL safety precautions.
Spraying Silicone - If you are spraying silicone, try to do your spraying outdoors in an open space. Anyone in the spray area must wear a NIOSH approved respirator, regardless if spraying outdoors or indoors.


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Start by airbrushing or spray painting into hard to reach places and crevices like the nostrils and the cheeks. Let set for several minutes and continue building up the surface. It's always best to apply in layers.
Do not apply too much paint at one time; this may cause it to pool or run.
At this point you have to be careful because the paint surface is still delicate and any marks may transfer into your mold.
You can let the paint cure for several hours or carefully force cure with a hair dryer. Be careful not to overheat your sculpture. You don't want your clay to start melting...!

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Once cured, you can check your plaster cast for areas that have "keys" which the Shell-Shock may get caught on; in this case, the eye socket.
I carefully added a little bit of clay and brushed on a coat of FuseFX F-201 Pure White, then I let it cure.



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Once the FuseFX F-201 Pure White skin is cured, I re-draw the line carefully with a marker. This line will permanently transfer onto your Shell-Shock mold.
The line is used as reference for where your clay sculpture ends. This is very useful when doing intrinsic painting.
Again be careful, the silicone surface may be cured but it's still delicate.


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For this piece I'm using Shell-Shock Slow Set.
Mix your Shell-Shock according  to Smooth-On's instructions. Please follow all safety precautions.
I start by brushing the Shell-Shock over the sculpted area first, being careful not to disturb the surface. I work quickly before the plastic sets, then I keep moving the Shell-Shock upwards till it starts to thicken.



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While the first coat is still setting it becomes very sticky. This is where I stick some bits of foam (Ethafoam or Styrofaom work well). The foam is used to create a hollow, and when covered with extra material, it becomes a tube. The tube gives it strength and also reduces the weight, not to mention save a little material.
I leave the area for the screwdriver insert open (top and bottom) so it can be filled with Shell-Shock. This area should be strong and solid.



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I brush on a few more layers and the job is complete. Let the Shell-Shock cure completely.


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Once completely cured, the Shell-Shock mold is easily removed by simply prying with a screwdriver.
Because the nostrils acted as keys, the clay nose was pulled off while removing the Shell-Shock mold. All the rest of the clay surface stayed intact.

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Close-up of the finished mold and sculpture:
Note the perfect pore detail in the mold. The marker line is permanent and clearly shows where the sculpture ends.
To remove the FuseFX F-201 Pure White, simply rub off with your hands or use an old toothbrush. The Marker line on the plaster positive was removed by using Toluene solvent.



Disclaimer: The suggestions and techniques provided in this web site are given in good faith.
If you try them, it is at your own risk. Guy Louis-XVI SFX and FuseFX take no responsibility and will assume no liability.
User shall determine the suitability of the product for the intended application and assume all risk and liability whatsoever in connection therewith.