There are several methods and methods possible for casting bronze. The following attempts to summarize the basic steps. A model is made, usually of wax. but if a rubber mold is made of it, it can also be made of clay, plaster, plastic or even wood or stone. The wax used for this is usually casting wax, paraffin or modeling wax.
With small wax models, the watering can can immediately proceed to the next step. With larger models or with models made of clay or plaster, for example, a hollow wax model must first be made. To this end, the watering can usually makes a rubber mold with a plaster support cap, which ensures that the rubber mold retains its shape.
Various materials can be poured into this rubber mold at a relatively low temperature, such as casting wax or plaster. In this case, a hard wax cast is needed, which is already at the thickness of the final bronze. Above a certain thickness it becomes difficult to cast bronze in solid form, due to uneven shrinkage of thicker and thinner parts. The watering can pours liquid wax into the rubber mold until a layer of wax has set in the mold at the correct thickness. The remainder is poured off, creating a hollow wax cast. This (hollow) casting is provided with wax protrusions that will later serve as pouring channels for the supply of the bronze and venting channels for the removal of the air in the mold. The wax casting, including channels, is covered inside and out with a refractory mass. This can be a mixture of plaster and chamotte or another shrink-resistant and refractory material. Stainless steel core supports ensure that the distance between core and outside remains the same. The finished mold is heated in an oven for a long period of time to melt out the wax and remove all moisture from the mold and, if it is plaster, all chemically bound water. A dry mold has now been created with a cavity in the shape of the model with sprues. Liquid bronze is poured into it. After cooling, the channels are sawn away and the casting is finished: burrs and protrusions are ground away and holes and unwanted cavities are hammered or welded closed. To protect against oxidation and for embellishment, bronze castings, especially sculptures, often have a patina layer applied with chemicals, the so-called patination.
Bronze is an alloy of copper and tin. The tin content can vary from about 10 to 30%. The alloy has a reddish to yellowish color, depending on the tin content. The period in history when mankind made extensive use of objects made of bronze is traditionally called the Bronze Age. Bronze is the first metal (except for a few earlier copper objects from the Neolithic) that was used by man in the Low Countries to replace stone in the Paleolithic. It is a tough and corrosion-resistant material that lends itself well to machining. A bronze surface acquires a green patina after a certain time.