A bronze sculpture can take weeks to make, and most of that time is spent on things you will never see: a figure shaped in wax, a mould of clay, a fire, a few seconds of molten metal. This is lost-wax casting, one of the oldest metalworking techniques in the world, and still the way every UMOJA bronze is made.
Here is how it works, step by step, as it is practised today in the workshop of Issouf Bonkoungou in Ouagadougou, Burkina Faso.
A technique thousands of years old
Lost-wax casting, cire perdue in French, has been used for thousands of years across Egypt, Mesopotamia, China and the African continent. In West Africa, the tradition goes back more than a thousand years: the bronzes of Igbo-Ukwu, in present-day Nigeria, date to around the 10th century, and the Benin Bronzes, cast by the Edo people from the 15th century onwards, are among the most celebrated works of the technique anywhere.
In Burkina Faso, it is a living craft. Issouf learned it as a child, on his father's lap: an art passed down from father to son.
Step 1: the model, shaped in beeswax
Everything begins with beeswax. The artist shapes the figure by hand, from imagination: the posture, the face, the hands. The clothing is formed from melted plastic, which gives the drapes their movement.
Every detail of this wax model, down to the marks of the tools, will appear in the finished bronze.
Step 2: the clay mould
The wax figure is then covered with clay mixed with donkey dung, kneaded and pounded until smooth. The clay goes on in two layers: a fine first layer that takes every detail of the wax, then a thicker second layer that holds the form. Small channels are left open so the wax can run out and the air can escape.
The moulds then dry in the sun, side by side. Each one holds the shape of a single figure.
Step 3: the wax is lost
The mould is heated. The wax melts and runs out through the channels, leaving inside the clay a hollow in the exact shape of the figure. This is where the technique gets its name: the original model is gone. About half of the wax is recovered and used again.
Step 4: the metal
Old bronze and brass are collected, sorted and melted down in the furnace at around 1,300 °C, until the metal glows like liquid gold. Nothing is wasted: the metal gets a second life.
Step 5: the pour
The molten bronze is poured into the hot mould. It flows into every hollow the wax left behind: every fold of fabric, every finger, every line of the face.
Step 6: breaking the mould
Once the metal has cooled, the clay mould is broken by hand to free the bronze. It cannot be used again. This is why a lost-wax bronze is never a copy: the model and the mould are both destroyed, and the sculpture exists only once.
Step 7: finishing and patina
The raw bronze is filed, cleaned and polished by hand. Then comes the patina, which gives the piece its colour:
- Rust and brown tones come from the oxidation of iron.
- Green and turquoise come from the oxidation of copper.
- Blue and red, often on the draped fabric, come from a coloured wax paste applied by hand.
Because every patina is laid by hand, two sculptures of the same subject never share exactly the same colours.
The artists behind UMOJA's bronzes
UMOJA works directly with three bronze artists in Ouagadougou:
- Issouf Bonkoungou learned the craft from his father and runs the workshop, where his apprentices are salaried and take part in decisions.
- Boukary Bonkoungou, his brother, grew up in the workshop and mixes bronze with wood and iron.
- Boureima Ouedraogo trained in drawing, bogolan and indigo before turning to bronze. He received the UEMOA creativity prize at SIAO in 2006.
One mould, one piece
When you buy a lost-wax bronze, you are not buying a product taken from a stock of identical copies. You are buying the result of a model, a mould and a fire that existed only once.
See the workshop in pictures in Inside Our Bronze Workshop in Ouagadougou, or discover the pieces: The Muses, The Dancing Muses, The Ballerinas and The Living Figures.