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BASIC TOOLS FOR WORKING STONE (for more images/less text visit the 12 page following HERE)

GENERAL USE OF THE CHISEL

The basic process of carving is to remove successive layers of waste material, with each removal further defining the ultimate form within the stone. Each type of carving chisel is used for removing and defining a particular layer of material. The order in which the tools are used follows the nature of the particular layer that is to be carved away. During the carving process, the first and least-defined layer is roughed-out with the point. Further roughing-out is done with the larger toothed chisels or claws followed by the use of medium and finer toothed chisels. The notched chisels and then the flat chisels are used to refine the form. The roundel or bullnose chisels are especially useful in refining concave areas of the form.

The chisels should be held at about a 45-degree angle to the surface of the stone while carving. Allow a slightly steeper angle for hard stones, while softer stones allow a shallower angle. If the chisel is held at too shallow an angle, the sharpened edge will not bite and the chisel will just glance off the surface. This is obviously not going to be very efficient — but if the chisel is held at too steep an angle, you run the risk of bruising the stone. Bruising is when a small area of the stone is crushed below the working surface, appearing as a white or lighter colored area. The bruise may not be noticeable while you are in the rough stages of carving, but it will become more obvious as the surface is sanded and polished. The only way to remove a bruise is to carve the entire area down below the bruise, which might be as deep as one half inch.

In addition to holding the chisel at the correct angle, it should be held with the cutting edge firmly pressed to the surface of the stone. Try to develop a rhythm with the hammer and chisel; tap to set the point of the chisel, then use a series of about half-a-dozen even blows to carve a furrow in the stone. If possible, the hammer should be held so that the swing is from your chest downwards. This position will be the least tiring and allow you the greatest degree of control for the effort.

CARVING TOOLS AND THEIR USE

STRIKING TOOLS such as hammers, mallets, and the dummy are used to deliver the blow to the chisel. Although smaller hammers are available, a one-and-a-half or a two-pound steel carving hammer will be the best choice with which to begin the carving. If the hammer is too light the carver's muscles must deliver much more force to the blow for the chisel to efficiently remove material during the roughing-out process. Later, when the refining stages of the carving are reached, the grasp of the hammer handle can be moved up towards the head of the hammer. Choking-up the grip this way allows a greater degree of control with less fatigue - while maintaining the weight to back up the stroke.

After the roughing-out stage when working soft stones the striking tool can also be a wooden carver’s mallet or a soft metal mallet called a ‘dummy.’ This allows one to use a softer blow (easier on the arm) while still removing material relatively efficiently on the soft stone.

THE PITCHING TOOL is more of a mason’s tool than a sculptor’s, but it can be used to remove a great deal of waste material at the initial stages of carving — but only if the carving block has flat-sawn faces. The pitching tool is struck with a forceful blow of the steel hammer to split corner or edge pieces off the sawn block. The pitching tool works by shock-fracturing the stone along the tools' square edge. This edge must be in full contact with the flat sawn surface of the stone in order to work. Because of this, the tool can only be used at the initial stages of the carving process before the flat sawn surfaces have been removed.

THE TRACER is also primarily a mason’s tool, the tracer looks like a pitching tool that has had its square edge ground sharp. Because the edge has been sharpened it may be used even on rough surfaces. The tracer is held with the shank perpendicular to the surface of the block. The tracer is struck repeatedly with a strong blow from a steel hammer. It is used to create a weak zone through the block of stone so that it will split into two portions. Repeated blows of the tracer, ‘tracing’ the split all the way around the block several times, creates the cleavage line.

THE POINT is used after any initial work with the tracer or the pitching tool. The point is used to rough-out the form. The single point of the chisel transfers all the force of the hammer blow to remove a chip off the surface of the block. The point is the most efficient chisel to remove large amounts of material from the carving. The block should be completely roughed-out to proportion with the point before any refining work is done with the other chisels.

THE TOOTHED CHISEL or CLAW follows the roughing-out process with the point. Initially the larger toothed chisels are used to define the surfaces of the form. This work is followed by the use of medium and finer toothed chisels. The toothed chisel, with its row of pointed teeth, acts like a rake to even out the surface irregularities left by the point. During use the chisel’s teeth should all be in contact with the stone in order to prevent breakage. For working broad or convex areas the toothed chisel should be wide. Conversely, while working tight or concave areas the chisel should be narrow. Coarse or large toothed chisels should be used first, then followed by smaller or finer toothed varieties.

THE FLAT-TOOTHED CHISEL is an intermediate between toothed chisels and flat chisels. It will give a much better definition to a surface than the toothed chisel, and it is used to refine the surfaces of the form. The notches allow for much better ‘bite’ into the stone than a flat chisel.

THE FLAT CHISEL is used to further refine the surfaces and crisp up the edges of the form. The surface they leave should remove any traces of carving from the previous chisels, including any ‘bruises’ below the surface.

THE ROUNDEL or BULLNOSE CHISEL is a variety of flat chisel that is especially useful in refining concave areas of the form. Their use is more-or-less the same, with the noteworthy exception of the curved corners that allow curved hollows to be worked without marring the adjacent surfaces.

THE BUSH HAMMER or BOUCHARD is used to pulverize the surface of the stone. The bush hammer has several rows of pyramidal teeth on its faces, usually fewer but larger teeth at one end and more but smaller teeth at the other. These teeth crush the surface of the stone and leave a distinct texture.

Before the advent of tungsten carbide tipped chisels, granite and similar stones could not be ‘carved’ with regular stone-carving chisels because high-carbon tool steel is about the same hardness as granite. The bushhammer was used to shape the surface of the stone by literally pulverizing the surface away. Nowadays, with carbide tipped chisels, diamond saws and grinders that allow hard granite to be carved and cut like marble, the bushhammer is used primarily for its textural qualities.

There are chisel-like versions of the tool, which are struck with the hammer. These bush chisels or frosting tools are held perpendicular the surface of the stone while working.