LOST-WAX CASTING

We welcome you on the journey through the different stages of creating an art work with the lost-wax casting process. It is a photographic journey to experience the places where we have been merging procedures, skills and techniques for over a hundred years. The distinctive features of the works at Cubro Artistic Foundry are the authentic symbiosis between the sculptor’s artistic and intuitive expression and the professional ability of our workers.

No work has ever been and will be the same as another. The matter is a living substance and every human intervention is exclusive and original.

Cast and Mold

The creative need is thousands of years old and since then, in terms of fusion, it is concretized first of all in a model. The sculptor, the designer or, more generally, the artist creates the model and it is in this phase that we can see it.

It can be made of plaster, wood, clay or plasticine, marble or any other material more suitable to express the idea. The model, which can also be created in 3D, becomes a form and prelude to the immortal beauty that bronze casting, or more generally metal casting, is able to communicate.

Model and Mold

It all starts when a silicone rubber mold is attached to the model; using a brush all the shapes are covered with an extremely thin first layer that envelops it completely. Once dried, other silicone rubber will be applied manually to give solidity to the mold structure.

In this phase, the craftsman will use all the knowledge that experience has provided him, paying attention to every detail, even the slightest, which will allow him to obtain a faithful reproduction of the project. Accuracy and extreme attention are the keywords.

Cords and textiles will support the plaster structure; the model will be completely covered, almost losing its nature.

On the work benches the silicone casts will be placed inside the plaster structures.

Cords and textiles will support the plaster structure; the model will be completely covered, almost losing its nature. Later we will have the exact negative of the orginal model.

On the work benches the silicone mold will be placed inside the plaster structures.

Wax Reproduction

A new phase begins. The smelter is ready to reproduce the wax work. With precise and continuous gestures, in empathy with the artist and his work, the craftsman will brush the entire silicone mold with molten wax.

Each gestures, in this phase, will determine the wax suface characteristics which, in turn, will be transferred to bronze.

It is time to close dowels and wax-coated silicone rubber with iron clips, thus rebuilding the mould.

The latter is now filled with other liquid wax, called Greek pitch, which will be poured and spilled several times depending on the thickness of the bronze which will be obtained. In the following step the final work suggests the craftsman’s sensitivity the way forward.

The wax thickness, in fact, with its peculiar details, will correspond to the metal thickness; the wax of this phase will become metal in the next one.

It is time to close the wax-coated silicone rubber with metal pins, thus rebuilding the mold. Molten wax, called Greek pitch, is poured into it and swished around until an even coating covers the inner mold surface. This is repeated until the desired thickness is reached. In the following step the final work suggests the craftsman’s sensitivity the way forward. The wax thickness, with its peculiar details, will correspond to the metal thickness; the wax of this phase will become metal in the next one.

The next step is fundamental. The smelter gives a soul to the hollow shape, determining the casting quality.

A mixture of red refractory material, “scagliola” and water will form a liquid mixture which will be poured into the mold to fill it. By solidifying, the soul of the model comes to life.

Adjustment

Once freed from the anchors and the mould, the wax sculpture reveals itself and it is ready for adjustments and possible modifications.

Special tools, boxwood sticks and rasps, but above all the hands of the artist and the craftsman under his indications, will deliver a perfect wax sculpture ready for the next phase: the preparation of the sprues.

Finishing

Once removed the mold, the wax sculpture reveals itself and it is ready to receive the finishing touches.

Special tools like boxwood sticks and rasps, but above all the hands of the artist and the craftsman under his indications, will deliver a perfect wax sculpture ready for the next phase: the sprues preparation.

Sprues

How does the liquid metal flow inside the form, how does it reach every hidden space, every minute detail? Thanks to the use of the so-called sprues that, applied and arranged together along the entire surface of the sculpture, do not leave any uncovered point.

Form and cooking

The sculpture is now ready to be hidden under an external covering of refractory material, which incorporates it and prepares it to receive the molten metal. At first with a brush and then, as refractory material solidifies, with its own hands, the smelter covers everything completely, including the sprues. The form is ready to go into the oven at a temperature that gradually reaches 600 degrees in about ten days. The refractory material cooks and the wax “gets lost” leaving an empty space that will be filled with the metal. That is the reason why the process is called investment casting.

Form and Burnout

The sculpture is now ready to be hidden under an external covering of refractory material, which incorporates it and prepares it to receive the molten metal. At first with a brush and then, as refractory material solidifies, with its own hands, the smelter covers everything completely, including the sprues. The form is ready to go into the furnace at a temperature that gradually reaches 1112°F in about ten days. The refractory material cooks and the wax model is “lost” leaving a cavity in the investment that will be filled with the metal. That is the reason why the process is called lost-wax casting.

Casting process

Bronze bars are already in the burnout oven, inserted little by little according to the quantity that will be needed. They melt at a heat that reaches 2372°F, revealing their fluid and incredibly liquid nature.

When the bronze is poured from the oven to the properly heated ladle, the metal shows its nature and energy.

Now the metal flows, poured suddenly to avoid oxidation and solidification. It fills the sprues and every void left available by the wax. It flows defining itself in a new form. The sculpture is now saturated, still imprisoned, but now solid and perfectly reproduced in the metal.

The metal flows, poured suddenly to avoid oxidation and solidification. It fills the sprues and every void left available by the wax. It flows defining itself in a new form. The sculpture is now saturated, still imprisoned, but now solid and perfectly reproduced in the metal.

Cleaning

In this phase the outer plaster of the form and the core are removed. The sculpture is free of any residue and shows its beauty. The inspiration of the artist, the far-sighted vision combined with the unceasing and skilled work of the artisans, now shows its immortal side.

Chisel and patina

The sculpture will be finished and chiseled. It’s time for the finishing touches, the sculptor or the chiseler will be able to intervene for the last time and for the last details or for the signature. The sculpture is ready for the patina, hot or cold, which through specific chemical reactions, define the artist’s intent and project.

Chisel and patina

The sculpture will be finished and chiseled. It’s time for the finishing touches, the sculptor or the chiseler will be able to intervene for the last time and for the last details or for the signature. The sculpture is ready for the hot or cold patina which, through specific chemical reactions, define the artist’s intent and project.