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1. Sculpting the portrait
The head is modelled life-size in clay over
a four to five day period. Ideally this is done in the home as
a relaxed atmosphere will bring out the true personality and features
of the person. A lacquer is painted over the sculpture when the
clay is leather-hard but not dried out. |
2. Mould making
'Banking up' the original
The first process a sculpture has to go through
is the making of a rubber mould. A master mould enables hollow
wax casts to be made in order to reproduce an edition of bronzes.
A void has to be created around the head. The mould may have to
be made in several sections, depending on the complexity of the
original, to avoid undercuts. |
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3. Mould making
The first clay blanket and keying
The sculpture is covered with a clay blanket
(5mm) the thickness of which will determine the thickness of the
void, later the rubber mould. Air vents and pourers are moulded
at the highest points, with key sausage-like edging and keyholes
in the clay case. |
4. Mould making
The first plaster jacket
A thick reinforced plaster jacket is built
up over this section of the mould and the other sections are then
treated in the same way, making sure the pouring and air vents
are kept clear. When the plaster casing is set, a section is taken
off, the clay blanket removed and the section put back in the
original position. |
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5. Mould making
Pouring the first rubber
Liquid black polysulphide rubber is poured
through the pourer, covering every feature modelled in clay, until
it emerges from the air vents. It will set within 90 minutes.
The procedure is repeated with all the sections. |
6. Opening the mould
A blunt chisel is pushed gently between
the sections to prise them open. The plaster section is lifted
off and the rubber mould gently peeled off the original sculpture
which is then carefully removed. The rubber mould is laid back
into the plaster jacket to hold the shape.
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