Techniques

The sculptures are first modelled in clay - a clay which contains "grog" - particles of fired clay that give support to large structures.  Unless very small, the sculpture is built on a support of wood and metal.  When the modelling is complete, the clay is left to dry to a leather-hard state.  Then the sculpture is cut in half and the halves removed from the internal support; this enables excess clay to be removed from the interior - it's a heart-stopping process as the sculpture is very fragile at this stage.

The two halves are joined together and the clay sculpture left to dry slowly over several weeks to ensure all moisture has evaporated.  It is then fired in a kiln over a 24-hour period -  the temperature gradually increasing until it reaches 1200°C.  This is called stoneware.  Stoneware is a very strong substance and should withstand frost - but there is always a possibility it could crack if left outside in really severe weather.  Stoneware can be patinated and coloured in many ways, and is often shown with a bronze effect - it is best waxed if kept outside.

Sculptures can be reproduced in bronze and then several copies can be cast from a mould.  The bronze can be patinated with oxides to obtain a variety of finishes.  Bronze is almost unbreakable.  The converting of the stoneware sculptures into bronzes has been done by Powderhall Bronze in Edinburgh.  Firstly, a latex mould is made of the sculpture.  This is then used to make an identical shape of wax; the wax is then coated with slip clay material then baked to "lose the wax" and convert the clay into a ceramic mould.  This mould is capable of taking the temperatures associated with molten bronze and is used to cast an identical replica of the original.  The process is very similar to that deployed by sculptors thousands of years ago and is extremely sensitive to fine detail.

Next the bronze is patinated; a choice of chemicals is available to give the required colours.  These are applied to the surface of the bronze and then baked in, using intense heat.  Finally the artist/owner can add highlights by simply polishing or continually stroking certain areas and further personalising the sculpture.

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