Bronze Explicacion De Como Sacar Pieza.docx

Bronze: Bronze, the Metal: Contrary to the familiar image of Greek sculpture as white marble statues, about half of all sculpture produced during antiquity was composed of bronze. The metal is a relatively strong alloy of two other metals, tin and copper. Bronze was also first and foremost the medium of ancient weapons used by the Greeks and most other cultures of their time. The metals characteristics of durability and strength coupled with a somewhat simple method of forging, made it superior for battle compared to the possible alternatives of stone, wood, tin, copper, or lead weapons. These facts made bronze a valuable metal needed by leaders and city states to create armies. None-the-less, bronze had many other facets of use to which it was applied. But whenever there was a war, the subsequent need for bronze caused anything, include the art of statues, made of the metal to be melted down into swords, shields, spears, and other weapons of war. The lack of modern bronze statues today is the result of this past wartime meltdown process. As a medium, bronze proved more versatile than marble and actually contributed to the transition of Greek sculpture into the Classical Period. The ability of bronze to hold its shape - no matter how complex - allowed sculptors to more easily experiment with less rigid poses. During the Archaic period, sculpture was restricted to the Eastern influenced stringency of pose, seen in the kore and kouros figures, partly by the tendency for their medium of either marble or terra cotta clay to crack if say an arm was extended or fall over if the body was turned in some angle. Not only was bronze a stronger lighter and medium, but leaden weights could easily be placed inside the hollow feet, enabling any number of sculptural poses that would otherwise cause the sculpture to topple over (or crack from internal stress if the statue was bolted to a base) if it was made of marble. The construction of life sized bronze statues involved many complications and required a special technique that took generations to develop. Creating solid bronzes that are life size required immense quantities of the valuable metal which distorted if dried as a large thick mass, so the trick was casting hollow sculptures. This type of casting was first mastered in ancient Mesopotamia, but around 550 BCE, it is

believed that the Greeks developed the technique independently or that they may have possibly acquired it from the Egyptians at that time.

Bronze, the Method of Sculpting: To understand the process of sculpting in bronze it aids us to look at the how the Greek method evolved. In the eighth century (900 BCE), before hollow casting in bronze was understood by the ancient sculptors, smaller solid statuettes had been made. These statuettes, typically handheld personal works, had been carved out of stone thousands of years prior to the eighth century BCE and their bronze construction was no great innovation, but it does signify a step along the path towards hollow casting. Larger, monumental sculpture in stone had been accomplished by the eighth century and it was only a matter of time before monumental sculpture in bronze would appear. The easiest method to create hollow bronze sculpture is not to cast them in one piece, but several, say seven or so. At first, these pieces were simply sheets of bronze hammered, as bronze is rather malleable or re-formable by smooching and flattening, and then welded together to create a closed hollow sculpture sometimes having a wooden frame. The technique the Greek sculptors used after 550 BCE to cast full size bronze sculptures is a bit more complex, for it does not rely on the welding of metal sheets but the on the making of a single piece formed directly from a mold.

Beginning with a clay or plaster full size model replete with all the details of the final work, a mold would be

created. The model, as it was made of a weaker material than either marble or bronze, was often made by covering a wooden frame, with head, arms, body, and legs, with a few layers of clay. The mold is created by covering the clay original with a half inch thick layer of wax and then a much thinker layer of clay. Before the mold (the mold consists of the outer covering of clay) has dried, several large nails were inserted though the clay and wax and tightly fit into the inner clay model. The reason for the nails is they act to brace the model in place, so it does not move once the wax in melted away (exiting though a small hole or two drilled in the mold but latter filled back up with clay), as is done when the entire mold and model are heated in the next step.

At this point, with the wax gone (a step where the clay mold and clay model hardened from the firing) and with the supporting function of the nails, there would exist a half inch thick air space, between the mold and model. This space is then filled with molten bronze poured down in a small hole or two in the mold. When the bronze has solidified and cooled, the clay mold is removed, revealing a hollow bronze statue. Well, it is not really hollow since the clay model has yet to be removed, but this is easily performed by scraping out the model from a small opening on the bottom. That entire process provided the easiest method to produce hollow bronze sculptures, but whether it or another, similar though more complicated, method was used by the first Greek casters cannot be determined. The

other method relied on a mold and a core (in the last method the model served as the core, but the core in this method is not the original model) but the major difference is instead of the mold being one piece it is made out of several. The first step of this process is the creation of these mold pieces. Exactly the same steps are followed as before in covering the clay model with wax and clay, but now the mold is removed (without melting away the wax, for this time the wax merely acted to prevent the clay from adhering to the model) in pieces: like one piece for the chest one for the back, two for the sides, and so on. The sculptor also had the option of applying the clay (composing the mold) directly onto the clay model (without the wax); this captured all the details of the original model but it involved shaving half an inch off the mold such that bronze could later fill this created space between the mold and core. Adding another twist to this method, all the pieces of the mold would be reconstructed, this time without the model inside, in effect making a hollow clay mold. Next, an adhesive material would be poured inside filling the hollow mold, and after the material dried into a solid form, all the pieces would once again be removed. The result of these steps is the creation of a core, which is essentially a carbon copy of the original clay model. This is actually an important step that makes this method revolutionary as it preserves the original model allowing the sculptors assistants to reproduce the same sculpture any number of times by simply taking more mold pieces from the model and then making additional core pieces. The wax is then removed from the mold pieces and the fine details of the final sculpture are easily carved into the soft clay interior of the mold parts. The details are carved into the inside of the mold because that surface will eventually be in contact will the molten bronze. Wax is then put back into the interior of the mold pieces over the details just added. After the core is complete and the mold finished and re-waxed this method actually branches with two different choices to move on from. The limitations of working with molten bronze encountered by the first casters probably made the choice of casting seven or so pieces from the various mold pieces and the core. This choice is easier to implement as each bronze piece cast dealt with a small portion of the entire sculpture like a leg or head, for example (again nails would support the mold over the core and the wax would be melted away prior to addition of the liquid metal). Once enough smaller bronze pieces were cast they would all be welded

together into the form of the finished sculpture, just like the hammered bronze sheets were connected by the more primitive sculptors. The other choice, requisite of a higher degree of experience in working with larger quantities of molten bronze, was the casting of one single bronze piece. This choice involved a complete reconstruction of the mold over the core, the insertion of supportive nails, the draining of the waxen inner lining, and then the filling of the empty space (left behind when the wax melted away) with molten metal. The name for these methods of casting bronze sculpture is cire perdue, translated quite fittingly to "lost wax" as wax is drained from the mold and "lost" in that sense.

Riace Bronze: Warrior Figure.

Any sculpture created from any of the previous casting techniques still needed some finishing touches after it was removed from the mold and after the core inside was scrapped out, before it was considered complete. First, the metal had to smoothed and polished and some details like hair were carved into the metal. A varnish was then applied to change the yellow color of the bronze to a darker or lighter hue, as was desired by the sculptor. Another finishing step was the addition of other metals, such as copper nipples and silver or gold for the lips and jewelry. Enamel or glass was often inset in the eyes to give them a realistic appearance and fine strands of copper were sometimes used as eyelashes and eyebrows. Unlike marble, the nature of bronze permitted the sculptor to utilize exquisite detail and extraordinary shine or dullness; in other words: although bronze was more costly, it was a versatile and powerful medium for the art of sculpture. The other bonus of sculpting in bronze was the ease of transportation, considering how light a hollow bronze statue is compared to a counterpart in marble. Indirectly, this transportation of bronze statues-primarily those shipped by boat - has helped build our supply of Greek original bronze sculpture. The not too uncommon storms that arise out of nowhere in the Mediterranean occasionally would sink trading vessels and with them their cargo of bronze statues that would all be covered with the thick mud at the sea floor. Although the covering mud makes the discovery of these sunken statues more difficult, it acts to preserve the metal that would otherwise corrode away. One such discovery has provided the Riace Bronzes, two key transitional sculptures into the Classical period, belonging specifically to the period, around 450 BCE, known as the Severe style.