Stone carving

From Wikipedia, the free encyclopedia

See also: petroglyph.

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

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 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 petroglyphs.

1 History
2 Stone carving considerations
3 Tools
4 See also
5 External links

[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 Memorialcarved from the Harney Peak granite of Mount Rushmore and the Confederate Memorial Park in Albany, Georgia are produced using jet heat torches.

[edit] Stone carving considerations

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 jewelery or larger items, and polished; this is sometimes referred to as lapidary, although strictly speaking lapidary refers to cutting and polishing alone.

[edit] Tools

Basic stone carving tools fall into three types:

Percussion tools — for hitting

such as mallets, axes, adzes, bouchards and toothed hammers.

Chisels — for cutting

such as lettering chisels, points, Pitching tools, and claw chisels.

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 use sudden, high temperature to shatter the stone.

such as laser cutting and jet torches.

The use of chisels for stone carving is possible in two ways:

The masons stroke

where a flat chisel is used at approximately 90 degrees to the surface in an organised sweep. It shatters the stone beneath it and each successive pass lowers the surface.