The Creation of a Bronze 

 

Pohutukawa bronze relief 

 

Here is how I created "Pohutukawa":

First the composition for the piece had to be worked out.


Pohutukawa at Wenderholm 75

Wenderholm Regional Park, inspiration for the bronze 


Pencil sketch for Pohutukawa 75

My sketched composition 

 

The drawing was scaled up in the computer to the finished size, then traced onto the prepared working surface.

The sculpting for "Pohutukawa" was done mostly in wax built over a wooden support. This support was in order to keep the overall thickness of bronze to less than 4mm and light enough to fix to the wall.

 

Pohutukawa wax trunk section 75

The work beginning to take shape

 

Pohutukawa wax completed 75

The completed wax sculpture, ready to take to the foundry 

 

When the wax work was complete it was taken over by foundry staff who took it from a wax form to a fully finished bronze.

I had fashioned "Pohutukawa" in two manageable sections. Branch-like solid wax rods, or sprues, were attached to strategic points of both pieces. Once the wax was burnt from the mould, these sprues would provide the tunnels through which the bronze could flow as it was poured in.

The sections were then ready for the mould-making and were dipped into a fine ceramic slurry. This hardened onto the wax like an egg shell, recording every detail. The two moulds were built up through a series of increasingly coarser layers before being placed in a kiln for burning out the wax.

 

Wax being burnt out of mould 75

Burning wax out of ceramic shell sections in a kiln

 

Pohutukawa pouring the bronze 75

The most dramatic and spectacular stage of the whole process - the pour

 

With the ceramic moulds set in sand boxes, expert hands controlled the flow of the 1300 degree molten bronze through the maze of cavities, transforming all the work to date into a durable piece of fine art.

Once the bronze had cooled and hardened, the sections were broken out of their moulds. With the sprues cut off, the sections were fixed together using bronze welding rods and the sculpture was ready for its finishing metal work or fettling.

Finally the patina was applied to the sculpture. Here the bronze was evenly heated with a torch and chemicals sprayed onto the bronze surface, causing a reaction which gave the work the desired colour.

Completed, the newly created bronze was ready for display.

 

Pohutukawa bronze on wall 75