Figure 20: View of two year old clay store with tractor trailer.
The aged clay is transported from the ageing pile to the production unit each day (about four
trailer loads per day). The factory should have a ramp leading to the clay store so the trailer
can simply dump into the store from above.
CLAY PREPARATION
Once at the production unit the aged clay is watered to bring it up to the correct water
content. The clay should be as stiff as possible while still being workable in the pressr this
generally works out to be between 23 and 27 per cent water by weight. The clay is then
chopped using gardening hoes to provide gross blending of water and clay. The chopped clay
is gathered and loaded into the pugmill. The pugmill outlet head is fitted with stretched
wires which automatically slice the outgoing clay into slabs. When the required length of
clay has been extruded it is sliced off using a wire mounted on a sliding frame. The blocks
of sliced clay are then stacked next to the flywheel press.
PRESSING
Slabs are peeled off the pugged blocks and slapped onto an oiled steel table. This both
lubricates the slab and expels air pockets from the clay. The oil is made up of 50 per cent
coconut oil and 50 per cent lamp kerosene. The oil that remains on the tile also slows the
drying of the tile which avoids cracking and warping.