Casting Bronze Through The Ages

It has been said that the process of casting bronze has seemingly transformed many cultures and societies throughout all of recorded history. Before it was introduced, people often favored the use of copper in their daily lives. Copper was used for many different functions, such as forging tools and making other items that needed to be rendered using a very hard material. Artistry was another area that benefited greatly from the use of this important material.

Unlike many other forms of metals, bronze is not found in a pure form, because it is an alloy. An alloy simply indicates that the material is composed of more than one type of metallic element. This specific medium is a mixture of copper and tin. Because tin is added to the blend in a small amount, which is less than four percent, it makes the copper much more durable and malleable. This makes the casting of bronze perfect for use in the creation of various types of sculptures.

In order for a work of art to be created, the process must begin with either the traditional hot method or the contemporary cold method. This is done either by pouring molten metals or a liquid and powder mixture into a mold, called a casting. Bronze is then added into the mixture after the initial molds are made, and the subsequent necessary steps in the process are then performed.

Prior to the 21st century, the primary method used to create bronze sculptures was hot casting. Bronze is added to molds that are shaped from a model. In the initial rendering, the model is usually made of a material such as clay. Then, using a mold that creates a hollow area about a quarter of an inch deep, several layers of a ceramic coating and wax are added, which lets the entire piece become rather hard. It is then fired, allowing the wax to melt away. Next, the hot alloy can be added to the mold after it has cooled and becomes hardened once again. The finished piece is then polished, so that all pieces that may have been left behind are removed. Lastly, the appropriate patina is applied, according to the artist’s instructions.

In just the last few decades, another technique has become popular, called cold casting. Bronze powder is mixed with a plastic resin in this particular process. The liquid solution is then poured into the mold, eliminating the need for the many different stages required of the hot process, which in turn makes the process less expensive. The reason for the creation of the cold version is because it adds useful products to a copper and tin mix, which also makes it much less expensive to create. Another benefit is that this method produces results which are nearly identical to the works made with only the initial alloy. The end result is difficult to differentiate from pieces that were created using the traditional method, and for this reason it is becoming the preferred choice.