Pre-consolidation drain
Having deposited solid clay on the mould cavity walls to the required thickness it is necessary to
expel from the mould that slip which remains fluid. The slip run-off valve and mould fill valves
open; the slip manifold valve remains closed, thereby establishing a route for slip to pass from the
mould back to the slip tank. Consolidation air valves open and air is introduced into that part of
the cast ware item containing slip. Under the influence of this pressure, slip is expelled from the
hollow parts of the clay ware item.
Typically, this part of the process cycle is around 60 seconds but will vary depending upon a
number of factors. Among these factors are –
• The volume of slip to be drained.
• The fluidity of the slip.
• The consolidation air pressure.
It is generally undesirable to extend the pre-consolidation drain period by more than a few
seconds beyond the point where the mould is fully drained.