This
is
Step Six:
Slip
casting
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Step One:
armature
Step
Two:
modelling
Step
Three:
intermediate
mould-making
Step
Four:
the rubber
model
Step
Five:
plaster
production
mould
Step
Seven:
fettling and finishing
Back to
the
Introduction
Removing the mould from the slip-cast model, Page Two of Three.
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The first mould part to be taken off is the last one that went on. On the top right of the starboard big side can be seen the filling hole, which is shared between the two big sides and the outer back legs segment. The waste created by the filling hole can be seen on the matching top left of the horse in the mould. A small sliver of slip has crept between the starboard side and the under segments. This is cleaned off - gently - with a short bristled paint brush. |
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This shows the port big side off, and the starboard and port face parts on the bench. Behind them is the smallest part which goes between the ears. Each part must be taken off with a straight draw otherwise small sections of soft clay will be ripped off by the hard plaster. That is why designing the mould to eliminate all undercuts must begin right from the initial modelling stage. The cast is still very soft. It might be rested at this stage in the warmth of the studio to harden a little more. The clay shrinks as it dries. This means it comes away from the plaster mould a little easier, as well as being firm enough to handle. However, too dry and the legs will shrink so much that they crack where they are held firm at the hoofs. |
The next page is removing the internal segments.