In the
direct method of stone carving, the work usually begins with the selection of stone for carving, the qualities of which will influence the artist's choices in the design process. The artist using the direct method may use sketches but eschews the use of a physical model. The fully dimensional form or figure is created for the first time in the stone itself, as the artist removes material, sketches on the block of stone, and develops the work along the way. On the other hand, is the
indirect method, when the sculptor begins with a clearly defined model to be copied in stone. The models, usually made of
plaster or
modeling clay, may be fully the size of the intended sculpture and fully detailed. Once the model is complete, a suitable stone must be found to fit the intended design. The model is then copied in stone by measuring with
calipers or a
pointing machine. This method is frequently used when the carving is done by other sculptors, such as artisans or employees of the sculptor. Some artists use the stone itself as inspiration; the
Renaissance artist
Michelangelo claimed that his job was to free the human form hidden inside the block.
Roughing out When he or she is ready to carve, the carver usually begins by knocking off, or "
pitching", large portions of unwanted stone. For this task, he may select a point chisel, which is a long, hefty piece of steel with a point at one end and a broad striking surface at the other. A pitching tool may also be used at this early stage; which is a wedge-shaped chisel with a broad, flat edge. The pitching tool is useful for splitting the stone and removing large, unwanted chunks. The sculptor also selects a
mallet, which is often a hammer with a broad, barrel-shaped head. The carver places the point of the chisel or the edge of the pitching tool against a selected part of the stone, then swings the mallet at it with a controlled stroke. He must be careful to strike the end of the tool accurately; the smallest miscalculation can damage the stone, not to mention the sculptor’s hand. When the mallet connects to the tool, energy is transferred along the tool, shattering the stone. Most sculptors work rhythmically, turning the tool with each blow so that the stone is removed quickly and evenly. This is the “roughing out” stage of the sculpting process.
Refining Once the general shape of the statue has been determined, the sculptor uses other tools to refine the figure. A toothed chisel or claw chisel has multiple gouging surfaces which create parallel lines in the stone. These tools are generally used to add texture to the figure. An artist might mark out specific lines by using calipers to measure an area of stone to be addressed and marking the removal area with pencil, charcoal or chalk. The stone carver generally uses a shallower stroke at this point in the process.
Final stages Eventually, the sculptor has changed the stone from a rough block into the general shape of the finished statue. Tools called rasps and rifflers are then used to enhance the shape into its final form. A rasp is a flat, steel tool with a coarse surface. The sculptor uses broad, sweeping strokes to remove excess stone as small chips or dust. A riffler is a smaller variation of the rasp, which can be used to create details such as folds of clothing or locks of hair. The final stage of the carving process is polishing. Sandpaper can be used as a first step in the polishing process or sand cloth.
Emery, a stone that is harder and rougher than the sculpture media, is also used in the finishing process. This abrading, or wearing away, brings out the colour of the stone, reveals patterns in the surface and adds a sheen. Tin and iron oxides are often used to give the stone a highly reflective exterior. Today, modern stone sculptors use diamond abrasives to sand in the final finishing processes. This can be achieved by hand pads in rough to fine abrasives ranging from 36 grit to 3000 grit. Also, diamond pads mounted on water-cooled rotary air or electric sanders speed the finishing process. == Zimbabwe Stone Sculpture ==