The Process

Stone Selection

There is a wide variety of stone materials used by artists. Each kind of stone has a unique hardness, carving technique and tools that must be used, and finishing properties (hold a polished surface). 

Generally, most artists use four categories of stone: soapstone, alabaster, limestone, and marble. These are all calcium-based. 

Soapstone is the softest of these (2 to 2.5 hardness) followed by Alabaster and is composed of gypsum or chemically, calcium sulfate. They can be sanded to get a nice shine and they make beautiful colorful indoor sculptures.

Limestone is composed of calcium carbonate (old bones) that got cemented into sedimentary stone. It is a little bit harder (2.5 to 3 hardness) and comes in many colors from gray to tan to yellow to white. Limestone can be polished but does not achieve the crystalline finish of alabaster or marble. It can be left outdoors.

Marble is limestone that has been heated and compressed – metamorphosed – into that crystalline carving stone. Its hardness varies quite a bit (3 to 4.5) with some of those in the Southwest U.S. being very hard (5). Like alabaster, marbles come in a wide range of colors holds a nice shine but can be displayed outdoors.

Idea & The Stone’s Will

“The stone and the artist are given equal voices in the artistic process that emerges as the finished piece.” I read this on another artist’s sight and have found it to be very true. The creative process in stone carving is one that must be fluid with the properties of the stone. Besides the shape and type of stone, the grain, hidden fishers, etc,… all contribute to what the stone carver can achieve. Too often, if the artist fights the nature or “will” of the stone – the piece fractures or cracks and the only recovery is the use of epoxy that is visible in the piece. Ture harmony can be seen when the artist and the stone are aligned. The artist Michelangelo claimed that his job was to free the human form trapped inside the block.

Tools

Stone carving is art through subtraction. This is basically achieved by use of either a percussion tool (hammer) for hitting something harder than the stone (steel chisel) into the material surface to break away parts or the use of a grinder power tool to remove material. The two most common percussion methods are by hand (hammer and hand chisels) or powered pneumatic hammers. Progress on shaping stone with a pneumatic hammer is faster as the air hammer place many thousands of impacts per minute upon the end of the tool. This type of tool creates the ability to 'shave' the stone, providing a smooth and consistent stroke, allowing for very larger surfaces to be worked quickly. The downside is the equipment needed is very large and very loud. It is this reason why my stone carving is done by hand or with a grinder.

Rough Out

The artist commences by knocking off or cutting large portions of unwanted stone. This "roughing out" stage is normally achieved with a point chisel, which is a long, hefty piece of steel with a point at one end (see video). A pitching tool may also be used at this initial stage; which is a wedge-shaped chisel with a broad, flat edge. The pitching tool is useful for splitting the stone and removing large, undesirable chunks. Those two chisels are used in combination with a masons hammer. It is at this stage when the stone may speak its mind and reveal what it doesn’t like by fracturing in an unplanned way. At this point, the artist may “decide” to head in another creative direction if a stone material isn’t working.

Fine Tuning

When the general shape of the statue has been achieved, the other tools used to refine the work are a toothed chisel or claw chisel, which has multiple gouging surfaces which create parallel lines in the stone. These tools are generally used to flatten out areas or add texture to the work. This part of the process generally uses a shallower hammer strike stroke. In addition, a dermal tool can be employed to hallow out or create deep groves.

Refining

The stone has changed from a rough block into the general shape of the finished work. 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. It is used broad, sweeping strokes to remove excess stone as small chips or dust (see video). A riffler is a smaller variation of the rasp, which can be used to create details such as folds or texture details.

Sanding & Polishing

The last stage of the carving process is polishing. A wide variety of sandpaper grates are used (rough to extremely fine) as a first step in the polishing process. The sandpaper’s stone grit is harder and rougher than the sculpture media, and this abrading, or wearing away, brings out the color of the stone, reveals patterns in the surface, and adds a sheen. This process normally is 16 hours or more of hand sanding in an ever-changing bath of water to remove the debris.  Additional polishing is achieved with rouge, stone sealants, Tin and iron oxides, and waxes to give the stone a highly reflective exterior.

Mounting

The last item that finishes the work and adds a greater perceived impression is the mounting base. This is attached to the work with pins, bolts, or adhesive. However, some art pieces are designed to stand on their own and the artist chooses not to add additional components to the work.