Research
COMBINING THE PLOTTER-CUTTER and THE RAM PRESS
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top of ram pressed plate with plotter-cut stencil. |
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base of ram pressed plate with plotter-cut stencil |
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clay slab placed on top of plotter-cut stencils in the bottom die mould. |
The combining of the plotter-cut stencils and the ram press has become the focus of my research. These mechanised technologies work extremely well together. By multiple pressing of the same piece, plotter cut stencils can be added during the making process. This enables the otherwise identical ram pressed pots to be individual one-offs or of a limited series. Both the top and bottom surfaces can have surface markings, with the thicker stencils giving deeper embossed markings.
The ram press cycle for multiple pressing with stencils or other material is as follows: switch the compressed air hose from the top die to the bottom die and vica versa; place stencil or other material in the bottom die for the base of the pot; place a slab of clay over this taking care not to move the stencil out of place; press the start button; the safety screen comes down followed by the top platten which presses the clay in between the moulds; compressed air is then automatically pumped through the top die mould which releases the clay; the top die mould is then raised up along with the safety screen; the clay remains in the bottom die mould; now switch the compressed air hoses back; place stencil or other material on the upper surface of the clay shape in the bottom die; now press the start button for the second pressing; the safety guard comes down followed by the top die mould which presses into the clay and stencils; compresses air automatically pumps through the bottom die which pushes the clay off the bottom die mould so that it is stuck to the top die mould; the safety screen and the top die mould rises with the clay shape stuck to it; place a ware board under the clay shape stuck to the top die mould; then, by standing on a foot pedal, compressed air is pumped through the top die to push the wet clay shape off the mould onto the ware board to remove the pot from the ram press.The stencils or other material have been pressed into the surface of the clay shape.
Removing the stencil material from the clay.
The stencils can be used as a slip resist, or can be removed leaving plain embossed pattern work. Some of the plastic and rubber stencils however have not removed well from the clay after ram pressing, pulling away some of the clay surface. A light application of silicone spray, as used by upholsterers, applied onto the stencil prior to use has prevented sticking. One unexpected finding is that a more porous surface on the stencil releases from the clay better than a non porous surface. For example, silicone rubber sticks to the clay after ram pressing, whereas expanded foam rubber releases without sticking. One expanded foam rubber I use is called "Plastazote". It is a vulcanised rubber,which means that it has been subjected to heat and sulphur, leaving the rubber surface more porous.
