Steve Winterburn | The Process Behind Bronze Sculptures

Though the foundry at Yorkshire Fine Arts has only been in operation since 2002, the methods used by the Winterburn family take their origins from practices established thousands of years ago. Through research and development, the Winterburns have refined their craft to combine the advantages of modern materials with traditional artisan methods.

All steps of the process are completed by hand on site, and each is unique in its preparation.

This is where the magic truly begins. Steve starts to form his ideas with loose sketches using variations of pencils and strengths of charcoal. Through shading, Steve forms an idea of how to bring his concepts into the three dimensional considering the anatomy and movement of the animal.

If clay is the flesh, then the armature is the skeleton, providing structure to the sculpture. The armature is made using a piece of flexible aluminium connected to a steel base to act as an anchor. Aluminium is a pliable metal, allowing the sculptor the tensile freedom required to find the perfect pose through movement.

Expanding foam helps Steve to form a rough shape, which he then cuts and carves back. After he achieves the basic form, then comes the wax - a more malleable medium than clay to build movement through the piece.

“I’ve become ambidextrous in sculpting over time, and with confidence things start to happen out of your control; you start out with one idea, and it goes in another direction, that’s the beauty of it. You don’t control it, it controls you – if you allow it to”

Once the sculpture is completed it will then be cut into pieces depending upon the size and complexity of the piece. The moulds are typically two parts and can consist of fibre glass, rubber or plaster. Each sculpture is unique, so the number of moulds will vary from one up to twenty. However, these moulds don’t last forever.

They have what’s called ‘mould life,’ which means they only have a finite number of uses before breaking down. The longevity varies from sculpture to sculpture, depending on the complexity. More involvement with the mould means faster wear, which is why Winterburn sculptures are of a small edition size; their rarity serving to add to their prestige.

After the moulds are completed, they are used to create a lost wax pattern. This is done through pouring and manoeuvring boiling hot wax around the inside of the mould; a process that is repeated until the wax is the correct thickness. It is of paramount importance that the wax is free from any air bubbles before being left to cool. It is then removed from the mould and then assembled, worked and prepared for mounting and spruing (which is the process of pouring bronze into a mould via a feed that allows air to escape, ensuring that air pockets do not result from the pour)

Ceramic shelling is completed by covering the lost wax with ceramic powder. The method is repeated multiple times, allowing each layer to dry completely before the next one is applied. It’s a time-consuming process and can take several days to complete. Some pieces can have as many as 10 layers.

When the shelling process is complete, the lost wax is burnt out from the ceramic shell, which entails heating the shells until they are glowing orange. The lost wax melts and is poured out, before the shells are then prepared for the bronze pour.

Here the bronze is heated to temperatures that exceed 1000 degrees. When it reaches a molten level, it is poured into the ceramic shells and left to cool. Once cooled, the shell is knocked away, leaving the bronze which is then ready for finishing.

“The anticipation for a pour, when we’re waiting for the ingots to become molten, is unbelievable. It’s nerve-wracking and exciting. You have seconds to get it in, and it either works or it doesn’t.”

“When you lift the crucible out there’s a moment, where the glow that comes out at 1200 degrees is just like the sun rising.”

This next part of the process involves removing the sprues (the feeds into which the bronze is poured), shot-blasting and chasing the overall detail of the sculpture. It is an important and intricate step; the artist must proceed with extreme care.

More detailed pieces, such as Steve’s looser works, require tools with varying thicknesses that are used to clean the sculpture and remove the ceramic coating. This is all done by hand to uncover the bronze beneath and add in any missing details, while removing impurities and sharp edges that may have formed during the bronze pour. All of these steps add to the uniqueness of each piece, giving them subtle, individual variations.

If a piece has been produced as a smaller section, it must now be welded onto the main body of work, ensuring each section locates correctly. When it’s cooled, all visible welds must be chased out and re-sculpted. This step may take several weeks to complete.

The sculpture is now ready for the final process; the patina. Heat opens the bronze’s pores as the chemicals are added to the surface and adhere to it. Different levels of heat mixed with varying chemicals create singularreactions each time, which is why these pieces are individual and cannot be replicated. There may be subtle variations across an edition, but no two patinas will ever be exactly the same. Finally, a wax is applied to polish and protect the sculpture.