Traditional Handcrafted Bronze

Article and Photographs Coutesy of Dinsdale Petch
Running Dog Bronze
www.dinsdalepetch.co.uk

Adam Binder and Dinsdale Petch are working together to produce Adam's new Bronze Sculptures and Miniatures. Mr. Petch has provided the information and photographs below to explain how bronze sculptures are made. We thank him for allowing us to share with you the details of this complicated process.

Traditional bronze is an alloy of tin and copper. Both these metals are inherently soft, but when mixed, or alloyed, they become much harder. Nowadays, the same result is achieved by mixing silicon with the copper. This addition creates a very fluid alloy which captures the finest details.

The Original 'Pattern'

The 'pattern' or the original piece to be copied can be of virtually any subject, an artist's original sculpture, a piece of fruit or an old sculpture.

Hand chased bronze master pattern

The Rubber Mould

Using a very high quality silicon polymer, the original pattern is covered. This then forms the master for as many copies as may be needed. Great care is taken to copy the tiniest details.

The Wax Pattern

A pattern is prepared in wax, using the rubber mould. The quality of the wax determines the degree of detail that can be reproduced. Again different grades of wax may be needed even within the same piece.

Hot wax being poured into open rubber mould

The image (above) shows a simple open mould made up of a rubber membrane supported by a composite case. Sculptures like Adam's, that are designed to be viewed from all angles, require rubber moulds made up of interlocking pieces to allow the delicate wax castings, complete with tails and tips of ears, to be removed from the mould without breaking.

Wax plaque on removal from mould

Wax Fettling

Any imperfections within the wax are repaired and any areas where the wax has ‘flashed’ are cleaned.

Wax trees awaiting dipping

Wax Tree

The wax patterns are 'gated', ie provided with a cylinder of wax through which the molten metal will enter the mould. When it is ready the finished object often resembles a tree.

Wax tree being dipped into first coat of ceramic slurry

A Ceramic Shell

The original ceramic coating or shell is now carefully created, built up by dipping and re-dipping the wax tree alternately into a mineral ceramic slurry then into graded ceramic sands and grits. Several layers are built up - each being allowed to dry thoroughly between dips.

Wax tree undergoing first ceramic dip

Raining ceramic grit and sand onto wet slurry on wax tree

Dewaxing

Once it is dry, the ceramic shell is placed in a kiln to melt the wax. The wax is collected and re-used for future wax trees. The ceramic shell is now hollow, the vacant space inside representing the original pattern.

Hot mould being removed from burn out kiln ready to have molten bronze poured into it

Melting the Bronze

The bronze is melted, an alloy of copper and silicon with traces of other metals. The entire crucible needs to be at exactly the right temperature and fluidity when the liquid is poured.

Raw bronze grain before being melted in a crucible in the furnace

Removing crucible from furnace

Lifting large crucible of bronze from furnace at 1100 degrees C

Pouring bronze into a small ceramic mould buried in sand

Pouring spare bronze into ingot moulds for re-use

Removing the Shell

About half an hour after 'the pour', the shell can be removed to reveal the bronze. The bronze itself has contracted slightly, thus detailed areas tend to grip the ceramic shell.

Destructive removal of ceramic mould from fresh cast bronze

Many hours later the final touches remove the slightest imperfections prior to patination

Finishing the Bronze

Where the wax tree had branches, the piece now has bronze branches which need to be removed, the cut faces smoothed and, if necessary, chased to match the surrounding texture.

Patinating the Bronze

The final touches involve polishing or patinating, which can produce a variety of finishes. There are many secret recipes involved to patinate the bronze. The art of the patineur, involves sensitivity to the subject and traditional patineurs would never reveal their recipes. Much
research, involving the most unlikely processes has been carried out to produce the richness of variety available to the contemporary bronze artist. It is important to remember patination is not paint - the rich colors are achieved by the use of many different chemical compounds that bring about 'rapid weathering' of the bronze surface. Once the desired colour has been reached, the surface is sealed with a durable lacquer prior to waxing.

Mrs. Petch said that during the development of Adam's bronze sculptures for his Exhibition, Adam was a regular visitor to the foundry. Both Mr. Petch and Adam experimented with different recipes in the patination stage to get the exciting finishes for his sculptures!

Finished Patinated bronzes (classic brown patina)

Many collectors of Adam's earlier work are familiar with the making of the marble/resin pieces. Mr. Petch summarized the similarities and differences between these two processes: "The rubber moulds used in the wax making stage at the beginning of the bronze process are the same as those used for resin production. Instead of resin, we pour in molten wax which, once set, is removed and dipped repeatedly in the ceramic slurry which, once set, forms a tough ceramic mould capable of receiving molten metal. The wax is melted away and replaced by the molten bronze. Once cool, the ceramic mould itself is destroyed to recover the raw bronze sculpture.
In order to produce each individual bronze, we need one wax and one ceramic mould - both of which are destroyed in processing." - Dinsdale Petch

To see original PDF file, click here.

Dinsdale Petch
Running Dog Bronze
www.dinsdalepetch.co.uk
4 The Square, East Buckland
Barnstaple, North Devon EX32 0TA
Tel: 01598 760558