Stone carving

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See also: petroglyph and sculpture.

Stone carver carving
stone, at the Cathedral
of Saint John the Divine, New York, 1909.

The Kilmartin Stones in
Scotland - a collection of ancient stone carved graveslabs

A famous khachkar at Goshavank
Armenia.

Stone carving is an ancient activity where pieces of rough natural stone are shaped by the
controlled removal of stone. Owing to the permanence of the material, evidence can be found
that even the earliest societies indulged in some form of stone work.

Work carried out by paleolithic societies to
create flint tools is more often
referred to as knapping.
Stone carving that is done to produce lettering is more often referred to as lettering.

Stone carving differs from stone as in marble quarrying in
that it is the act of shaping or incising the stone, whereas quarrying is the
activity of acquiring useful stone, usually in blocks, from geological
sources.

The term stone carving is of particular significance to sculptors being a reference to
a particular way of producing sculpture, as opposed to modelling in clay or
casting. The term also refers to the activity of masons in dressing
stone blocks for use in architecture, building or civil engineering. It
is also a phrase used by archaeologists, historians, and anthropologists to
describe the activity involved in making some types of petroglyphs.

Contents

1 History

2 Stone
sculpture

3 Stone carving
considerations

4 Tools

5 Gallery

6 See also

7 References

[edit]
History

The oldest known works of representational art are stone carvings. Often
marks carved into rock or petroglyphs will survive
where painted work will not. Prehistoric Venus figurines such as
the Venus of
Berekhat Ram may be as old as 800,000 years, and are carved in stones such
as tuff and limestone.

These earliest examples of stone carving are the result of hitting or
scratching a softer stone with a harder one, although sometimes more resilient
materials such as antlers are known to have been used for relatively soft stone.
Another early technique was to use an abrasive that was rubbed on the stone to
remove the unwanted area. Prior to the discovery of steel by any culture, all stone
carving was carried out by using an abrasion technique,
following rough hewing of the stone block using hammers. The reason for this is
that bronze, the hardest available metal until steel, is not hard enough to work any but the
softest stone. The Ancient Greeks used the ductility of bronze to trap
small granules of carborundum, that are
naturally occurring on the island of Milos, thus making a very
efficient file for abrading the
stone.

The development of iron made
possible stone carving tools, such as chisels, drills and saws made from steel, that were capable of being
hardened and
tempered to a state hard enough
to cut stone without deforming, while not being so brittle as to shatter.
Carving tools have changed little since then.

Modern, industrial, large quantity techniques still rely heavily on abrasion
to cut and remove stone, although at a significantly faster rate with processes
such as water erosion and diamond saw cutting.

One modern stone carving technique uses a new process: The technique of
applying sudden high temperature to the surface. The expansion of the top
surface due to the sudden increase in temperature causes it to break away. On a
small scale, Oxy-acetylene torches are
used. On an industrial scale, lasers are used. On a massive
scale, carvings such as the Crazy Horse
Memorial carved from the Harney Peak granite of Mount Rushmore and the Confederate
Memorial Park in Albany, Georgia are produced using jet heat torches.

[edit]
Stone sculpture

Main article: Stone sculpture

The Tang Dynasty Leshan Giant Buddha,
near Leshan in Sichuan province, China. Construction began in 713,
and was completed in 803, making it the largest stone-carved Buddha in the
world.

Carving stone into sculpture is an activity older
than civilization itself. Prehistoric sculptures were
usually human forms, such as the Venus of Willendorf
and the faceless statues of the Cycladic cultures of ancient
Greece. Later cultures devised animal, human-animal and abstract forms in stone.
The earliest cultures used abrasive techniques, and modern technology employs
pneumatic hammers and other devices. But for most of human history, sculptors
used hammer and chisel as the basic tools for carving stone.

The process begins with the selection of a stone for carving. Some artists
use the stone itself as inspiration; the Renaissance artist Michelangelo claimed that
his job was to free the human form trapped inside the block. Other artists begin
with a form already in mind and find a stone to compliment their vision. The
sculptor may begin by forming a model in clay or wax, sketching the form of the
statue on paper or drawing a general outline of the statue on the stone
itself.

When s/he is ready to carve, the artist usually begins by knocking off large
portions of unwanted stone. This is the "roughing out" stage of the sculpting
process. For this task s/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. Those two chisels are
used in combination with a lump hammer.

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, usually in combination with a
wooden mallet.

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 color 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.

Sculptures can be carved via either the direct or the indirect carving
method: indirect carving is a way of carving by using an accurate clay,
wax or plaster model, which is then copied with the use of compasses, also
called "proportional dividers" [1]
or a pointing
machine. The direct carving method is a way of carving in a more
intuitive way, without first making an elaborate model. Sometimes a sketch on
paper or a rough clay draft is made.

[edit]
Stone carving
considerations

'Arabic' style carving on ashlar building blocks, Beith,
Scotland.

Stone has been used for carving since ancient times for many reasons. Most
types of stone are easier to find than metal ores, which have to be mined and
smelted. Stone can be dug from the surface and carved with hand tools. Stone is
more durable than wood, and carvings in stone last much longer than wooden
artifacts. Stone comes in many varieties and artists have abundant choices in
color, quality and relative hardness.

Soft stone such as chalk, soapstone, pumice and Tufa can be easily carved with
found items such as harder stone or in the case of chalk even the fingernail. Limestones and
marbles can be
worked using abrasives and simple iron tools. Granite, basalt and some metamorphic stone is
difficult to carve even with iron or steel tools; usually tungsten carbide tipped
tools are used, although abrasives still work well. Modern techniques often use
abrasives attached to machine tools to cut the stone.

Precious and semi-precious gemstones are also carved into
delicate shapes for jewellery or larger items, and polished; this is sometimes
referred to as lapidary,
although strictly speaking lapidary refers to cutting and polishing alone.

When worked, some stones release dust that can damage lungs (silica crystals
are usually to blame), so a respirator is sometimes needed.

[edit]
Tools

Basic stone carving tools fall into four categories:

Percussion tools for hitting - such as mallets, axes, adzes, bouchards and
toothed hammers.

Tools for rough shaping of stone, to form a block the size needed for the
carving. These include feathers and wedges and pitching tools.

Chisels for cutting - such as lettering chisels, points, pitching tools,
and claw chisels. Chisels in turn may by hand held and hammered or pneumatic
powered.

Abrasives for erosion - such as carborundum blocks, drills, saws, grinding
and cutting wheels, water erosion machinery and dressing tools such as French
and English drags.

More advanced processes, such as laser cutting and jet
torches, use sudden, high temperature to shatter the stone.

The use of chisels for stone carving is possible in several ways. Two
are:

The masons stroke, in which a flat chisel is used at approximately 90
degrees to the surface in an organized sweep. It shatters the stone beneath it
and each successive pass lowers the surface.

The lettering stroke, in which the chisel is used along the surface at
approximately 30 degrees to cut beneath the existing surface.

There are many types and styles of stone carving tools, each carver will
decide for themselves which tools to use. Traditionalists might use hand tools
only.

Lettering chisels for incising small strokes create the details of letters
in larger applications.

Fishtail carving chisels are used to create pockets, valleys and for
intricate carving, whilst providing good visibility around the stone.

Masonry chisels are used for the general shaping of stones.

Stone point tools are used to rough out the surface of the stone.

Stone claw tools are used to remove the peaks and troughs left from the
previously used tools.

Stone pitching tools are used to remove large quantities of stone.

Stone nickers are used to split stones by tracing a line along the stone
with progressive strikes until the stone breaks along the line.

Powered pneumatic hammers make the hard work easier. Progress on shaping
stone is faster with pneumatic carving tools. Air hammers (such as Cuturi) place
many thousands of impacts per minute upon the end of the tool, which would
usually be manufactured or modified to suit the tool. This type of tool creates
the ability to 'shave' the stone, providing a smooth and consistent stroke,
allowing for larger surfaces to be worked.

Among modern tool types, there are two main stone carving chisels:

Heat treated high carbon steel tools - Generally forged

Tungsten carbide tipped tools - Generally forged, slotted, and carbide
inserts brazed in to provide a harder and longer-wearing cutting edge.

[edit]
Gallery

Sculptor at work

Direct carving method:'The Unknown Righteous Among the Nations', red
granite sculpture by Shlomo Selinger (b. 1928), 1987, Yad Vashem, Jerusalem,
Israel

Using plug and feathers to
split a block of marble from the quarry.

Pitching tool used in preliminary rough shaping blocks of
stone.

Carrara marble
quarry.

[edit]
See also

Chalk
carving

Khachkar

Stone
sculpture

Stonemasonry

Marriage
stone

[edit]
References

^
Hoffman, Malvina, Sculpture Inside and Out, Bonanza Books, New York,
1939 p. 235

Wikimedia Commons has media related to: Stonemasonry

Wikimedia Commons has media related to: Stone
chisels

Retrieved from "http://en.wikipedia.org/wiki/Stone_carving"

Categories: Carving | Stone | Art media |
Monumental
masons

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This page was last modified on 29 January 2011 at
06:38.

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