Plaster bats can be used to aid in modeling accuracy, but they must be checked for symmetry. Distorting plaster bats using balloons allows them to perfectly follow complex shapes like cisterns. Distorted plaster can also be useful for creating smooth mould seams when making blocks. Modifying mould seams by allowing plaster more room to distort and using clamps can help tighten seams and improve seals.

1. Plaster Template bats and distortion
to aid Modelling accuracy
• Most new designs today are modifications of existing items in an effort to save time and
occasionally the number of new cases required. Using pre drawn and shaped plaster bats are
a common aid to Modelling. However are the Plasters bats symmetrical? The following sketch
Fig 1 is a useful method
• The drawing in Fig 2 shows how plaster distortion can be used to the modeller and block
makers advantage

2. When the plaster bat has been drawn and shaped a cut is made along the dotted line. One half is
placed on top of the other using line X as a temporary centre line. The additional line X is
approximately 15mm both sides of the centre line. Symmetry can then be accurately checked.
Fig 1

3. A Cistern body clay thickness can be accurately achieved using pre shaped and measured flat plaster bats.
Balloons lightly inflated will apply pressure to the flat bats and they will distort to follow perfectly the cistern
shell shape. Plaster distortion can be used to advantage creating smooth and accurate mould seams during
block making. Particularly useful to create the bow on a Basin front.
Fig 2
Cistern block body.

4. If the Block was cased with an overlooked distortion or part of the case moved during one of the processes then reducing Not
increasing the seam thickness should yield a seam seal improvement. At least if the mould continues to leak then the residue will
fall away from the critical mould seam. Keeping the mould seam clean will be easier for the operative. An even better result will
be obtained if view 2 is also applied to the top core. View 4 depicts this.
View 1 View 2

5. A new wet mould can be modified by hand using a router machine or by hand for a trial. The actual seam will
now be visible and its possible the use clamps to close the gap even tighter as the plaster has room to distort .
Closing the gap on a 50 or 60 mm mould seam is not always possible.
View 3
View 4
Top core Modified top core
Mould
side Modified
side