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Brush-On 40, Plasti-Paste: Working Together
Brush-On
40™, Plasti-Paste™ Combine to Create Perfect Sculpture
Reproduction . . .
Tim Maslyn of Maslyn Studios (Belle Mead, New Jersey) was recently
commissioned by Queensboro College (New York City) to reproduce a
valuable sculpture created by the late Joseph Brown, Professor
Emeritus Of Sculpture at Princeton University. The original was a
36” (1 meter) tall head of a boxer entitled, “The Winner”,
in memory of Brown’s brother, Harry “Kid” Brown and was
sculpted in 1952.
The goal was to reproduce the original and make an exact replica
that captured every last bit of detail. The finished copy should
have a metallic finish (look like real brass) and be lightweight
so that it could easily be transported and minimize on material
costs. Maslyn was also under a time deadline and had to make the
reproduction quickly.
Materials Maslyn chose to make the reproduction included Brush-On
40 mold rubber, Plasti-Paste Mother Mold Material and Smooth-Cast
325 Colormatch liquid plastic mixed with brass powder to make the
finished casting.
Maslyn began by applying Universal Mold Release to the model
surface and letting it dry. Next, he mixed Brush-On 40 and applied
the initial coating which is a thin “detail” coat.
After the rubber becomes “tacky” (30 minutes at room
temperature), a second coat is mixed and applied. This time, color
pigment is mixed with the rubber to distinguish this layer from
the last. This will help to ensure a uniform coating each time and
eliminate “thin spots” in the finished mold.
After the second coat is applied, cut pieces of nylon rope were
encapsulated in fresh rubber. These served as “registration
keys” to align the finished rubber mold and the support shell.
The rubber was built up on subsequent layers, with four coats
total applied to achieve a 3/8-inch mold wall thickness. Again,
every other coat was pigmented to ensure thorough coverage of each
layer.
After the rubber was fully cured, clay shims were applied to form
parting seams. Release agent was thoroughly applied to the clay
shims and rubber surface to release the Plasti-Paste mother mold
material.
The mother mold was applied in three sections for easy release and
to avoid mechanical lock. Maslyn also embedded pieces of
electrical conduit into the Plasti-Paste to create grips for
easier handling and transport of the mold.
To begin the casting process, both halves of the rubber mold were
sprayed liberally with Universal Mold Release.™ Brass powder was
then mixed with Smooth-Cast 325 Colormatch™ fast setting resin.
The SC-325’s neutral color is perfect for the addition of both
colors and metal powders.
The next step was to apply and initial “gel coat” which simply
means that an initial thin layer of the brass powder/resin blend
was brushed into the mold cavity. The two halves of the mold were
then put together and the seams painted with additional
powder/resin blend.
Mold sections were tightly secured with mold straps and the entire
apparatus was inverted (turned upside down) and placed on a rotocast machine foundation. Plasti-Paste was again mixed and packed
around the model base to form a contoured foundation that kept the
entire mold structure level and held it in place during
rotocasting.
A board with a pre-drilled hole served as a cap to contain the
resin as the roto cast machine rotates. SC-320 resin was poured
into the mold through the hole which was then capped. The machine
rotated at at 360° for 10 minutes. The SC-320 coated the inside
of the mold, thereby reinforcing the metal gel coat.
Two additional pours of SC-320 were rotocast to build a suitable
thickness. Following demold, the casting surface is buffed with
steel wool to bring out the metallic highlights. A sealing coat of
clear acrylic spray was then applied. The finished casting is
lightweight and looks like real brass at a fraction of the cost of
casting the piece in real brass.
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Smooth-On