The process of lost wax casting has been followed since ancient times, and the proof that such process existed dates back to as early as 5,000 years ago. The techniques followed for lost wax castings in general has evolved over the years and different tools, equipment and materials are used today, and the process in itself continues to change and evolve still date. However, the basics of the process of lost wax castings remains the same, and even though the process is heavily time consuming, challenging and tiring, it is still followed because of its accuracy and replicating each and every detail minutely.
The process of lost wax castings can be detailed as below, step by step –
- The process starts with artist creating model, mostly in wood, ceramic or clay, or any other such material.
- This model that the artist creates is then put in a very soft and shapable material, which is held tight by the outer layer of hard covering, which remains intact. The model after being allowed to settle in properly is then removed, which leaves its impression back.
- Then fireproof clay or a similar fireproof material is put into the same mould, which then is allowed to settle. It takes the exact impression of the model designed. The shape it takes is highly accurate and no details are missed in the process.
- This fireproof clay model is then scrapped on its surface to make it a size or two smaller in dimension than the actual size meant. When this model is again put into the model after being scrapped, there is a very thin space left, which is where the bronze or the other metal desired is poured. The thickness of the bronze or metal mould that comes out would be of the size of the scrapping done, which can be calculated as desired.
- The gap between the mold and the mould is then filled by pouring in hot wax. This results in getting the clay model that has a layer of wax on it. It is then polished and processed to perfection manually.
- Then the pipes namely gates and sprues are attached to the above model.
- Then the ceramic that is finely granulated is applied all over the wax model as well as the network of pipes till thick, and then it is heated. This helps the wax to melt away. The wax is lost in the process, and hence, the name.
- Except on the top, the mold is layered with protective metal coating. The mold, also known as investment mold is heated to over 1,000 degree Fahrenheit.
- Molten bronze is then allowed to pass in investment mold, which acquires the empty space. When cold, mold and cladding is broken carefully. The highly intricate bronze sculpture appears.
- The networks of pipes are carefully removed, and the bronze surface that remains is polished and chiselled. It is cleaned further to give a neat look.
This is the process of lost wax casting. It does take a bit of more time than other processes known, but the results are amazing and it has an aesthetic cultural value attached to it as well, and the process is industrially followed as well these days to manufacture intricate manufacturing metal parts.