The subject tends to get short shrift in histories of this period because, as we look back, the big story of the era seems to be Modernism, which was then gathering steam, and would become the direct forerunner of the visual arts of today. It is easy to lose sight of the fact the Academy was decidedly center stage until well into the Twentieth Century, and Modernism the minor player in all of the plastic arts, but particularly in sculpture. In 1912, at age 31, five years after he had painted Les Demoiselles d'Avignon, Picasso's London dealer was still selling his works for between two and twenty English pounds--as little as a workman's weekly pay. The work of Henri Matisse (1869-1954), one of the first artists of that generation to become successful, first entered a public collection in the same year, when his 1910 Still Life With Geraniums, was given to the Pinakothek der Moderne in Munich. In contrast, between 1900 and 1920, the paintings of Lawrence Alma-Tadema (1836-1912), the Dutch-English painter of Classical scenes, were routinely sold for up to 6000 pounds--equivalent to half a year's income for the president of a major bank or corporation. Figurative works by prominent scultptors working in the Academic style were also valued in this range. For instance, the first two full-size marble versions of Rodin's The Kiss each sold for 20,000 French francs in 1888, and 1900. Comparing money across such a long period of time is complicated, but this would be equivalent to at least twenty years pay for a working man, double that for a working woman, perhaps a million 2013 dollars.
This was to some extent a consequence of technological change. The invention of scores of synthetic pigments, starting in the early Nineteenth Century, made painting cheaper, while simultaneously expanding the palette with vibrant greens, yellows, and blues which had formerly been either unknown or enormously expensive. Many of these new pigments were of unprecedented strength and/or opacity, making it possible to paint alla-prima, what formerly had required patient layering-on over a period of weeks or months. The invention of oil-paint in a tube, in 1841, turned painting, for the first time, into something that could be easily done outside of studio. Tube-paint catalyzed a chain of other inventions, such as the portable easel, aimed at making painting still more portable. Suddenly, painting was an activity that could be done out of a kit the size of a briefcase, indoors or out. See Revolution in Paint  [Hurt 07].
The usual practice in the late Nineteenth Century, for major pieces that did not have a prior commission, was to exhibit the piece in plaster first, and execute in either bronze or marble if and when a purchaser was found. But even in plaster, a large piece requires significant direct cost, and stable commercial space.
Demolition of the spectacular Pennsylvania Station in New York, designed by the firm of McKim, Mead, and White, and opened in 1910, was already being proposed in the 1950's, and was finally accomplished in 1963. So little was the style valued, that the massive columns and other decorative elements were not even salvaged, but simply were simply trucked to the NJ Meadowlands and dumped for land fill.
The hand-held pneumatic air hammer for stone carvers was patented in 1888. The first hand-held electric drill was patented in 1895, but was first manufactured in roughly its modern form in 1917. Silicon carbide was invented in 1891, and tungsten carbide tools were introduced in the 1930's. Modern tool steels, as opposed to simple high-carbon steels, is a vaguer category, but most of the important alloys and processes also date from approximately the turn of the century.
Interestingly, much older tools from Fourth Millennium BCE Egypt have been found in ancient tombs. Even the "Copper Age," tools remain very recognizable.
Except for a few stones, e.g., quartz crystal and jewels stones, in which the entire stone is a single large crystal.
Although copper is ordinarily very soft, "cold forging" can make some non-bronze copper alloys as hard as some bronze. This technique, however, is more applicable to edged weapons than to stone working tools, which take much more abuse and have a short working life without constant maintenance. Unlike copper, bronze does not harden significantly under cold forging.
Rudolph Wittkower cites experiments conducted by the Belgian sculptor H. J. Etienne, using bronze tools made of alloys similar to those available to the ancient Greeks [Wittkower 91].
Meteoric iron, the rarest of the metals found in nature in metallic form, was known long before the Iron Age, but it was regarded as a precious metal. Meteoric iron can be easily distinguished from manufactured iron by its high nickel content.
In making wrought iron, the oxygen is chemically removed from the oxide (i.e., the iron oxide is "reduced") without the metal ever being in a liquid state. The initial result of this processing of the ore is an impure spongy blob of iron particles and mineral slag, called a "bloom." The bloom must be worked (i.e., wrought) with heat and hammering, to shake out the crumbly mineral slag, and pressure-weld the iron particles into a solid bar. The resulting metal tends to be of poor quality, soft, and full of impurities.
A few ancient cultures could also produce iron in volume, much as is done in the modern world, by smelting ore using coal or coke. The resulting cast iron, however, then as now, has an extremely high carbon content, making it too brittle for many structural applications and tools. Until the middle of he Nineteenth century, industrial steel production mostly still relied upon carbuerizing wrought iron. The Bessemer process, patented in 1855, for converting pig iron into steel by removing the carbon, drastically reduced the cost of steel and increased the supply. This process was the most important technological discovery of the Second Industrial Revolution, which began in about 1850.
Two pieces of clean iron or steel that are hot, but not molten, can be welded by beating them together between hammer and anvil.
See Shiela Adam's The Technique of Greek Sculpture [Adam 66].
Some authors describe the progression as being to smaller and smaller tools. The rationale for this assertion is not clear--the size of a punch at its tip is the same regardless of the tool's overall size. Progressively lighter blows with the same punch seems more likely.
Emery is a complex mineral composed largely of corundum, a crystalline form of aluminum oxide, Al2O3, which is the second hardest material found in nature, capable of scratching anything except diamonds. Rubies and sapphires are corundum colored with trace amounts of other elements. For thousands of years, emery was found in abundance only on Naxos, one of the Cyclades Islands, and is in fact named for the Emeri Peninsula on Naxos.
Cutting the distance between points in half quadruples the number of times it must be done. Cutting the distance by three quarters implies eight times more punchings, and so on.
Greek sculptors made one major exception to the general practice of painting sculpture: the flesh of women was usually left pure white. This was also the custom in decorated pottery. Men's flesh was usually colored, and women's left white.
Phidias Showing the Frieze of the Parthenon to his Friends, Birmingham Museum and Art Gallery, Birmingham, England. Lawrence Alma-Tadema [Public domain], via Wikimedia Commons
The absence of evidence of the use of the oblique punch stroke in this period is often attributed to tradition, but there is also a good technological argument for its protracted use.

In this period, we also see the claw chisel used in the vertical mode, in which it functions more like a bush chisel, more frequently than in subsequent eras, which further argues that the steel was marginal.

Drills twirled between the palms are still used today, for instance in the course of mechanical copying, to adjust the precise depth of a hole being drilled to mark the location of the finished surface, which would typically be measured to approximately one millimeter accuracy.
As late as 1939, Malvina Hoffman, in Sculpture Inside and Out  [Hoffman 39] still clearly thinks of electic drills as exotic machinery, referring to an electric hand drill as "an electrical drilling machine," and apparently uses only manual tools in her own studio. She herself is shown using a simple drill twirled between the palms for the precision drilling used to mark copying points. This practice is still common even now for this one special purpose, because it is easy to control the depth of the hole.
Tubular copper bits did not have metal cutting edges, but instead applied pressure to dry sand, which was poured into the kerf. See Ancient Egyptian Materials and Industries,  [LucasHarris 62].
Neither was the most celebrated art form. Work in chryselephantine, i.e., composite constructions covered in ivory and gold, sometimes colossal in scale, had the highest status in Archaic and Classical Greece. The reconstruction pictured in Figure *, of the statue of Athena Parthenos from the Parthenon replica in Nashville, TN, gives some idea of what these pieces were like. This reconstruction is a composite of images of the sculpture from ancient times, and is regarded by art historian as very realistic. No major works, and very few examples of any scale, have survived to the present day.
This was even more true for gold-encrusted chryselephantine temple statues, at least some of which were made with detachable gold parts, which could be removed and melted down in time of need, and replaced with fresh castings after the crisis had passed.
The feldspars are a family of minerals composed of silicon, combined with various combinations of the four metals calcium, sodium, potassium, and aluminum.
Quartz is a crystalline mineral, SiO4, with the molecules arranged in the form of tetrahedrons of one silicon and four oxygen atoms. As each oxygen atom is shared among two silicon atoms, the overall formula is SiO21.
Mica is a family of phyllosilicate minerals that have a crystal form of parallel sheets.
A bruise is a milky area in which many invisibly small cracks cause a region of greater opacity in a stone. Bruises can be anywhere from millimeters to inches deep and are not removable.
Fat floats, while lean meat and bone sink. People of average build float when their lungs are full, and sink when they exhale, so their overall density is approximately equal to water. The obese float even if they exhale, particularly if they are not muscular, and ripped athletes have trouble floating at all.
Gian Lorenzo Bernini A Faun Teased by Children, detail, 1616-1617 Metropolitan Museum of Art, New York, Marble, H. 52 in.
Unknown French, Bust of a Magistrate, Metropolitan Museum of Art, New York, Marble.
Beware that some of the recipes call for lead and mercury. These metals are bad news--toxic, absorbed by ingestion or through the skin, extremely unfriendly to the environment, and highly regulated in the workplace and as toxic waste, for very good reasons. Fortunately, they aren't essential.
Nicolas Cordier, "St. Sebastian", marble, Rome, Sta. Maria sopra Minerva, Aldobandini chapel (detail).
Christophe-Veyrier, Bust of Marquis Jean Deydé, detail, 1684, Metropolitan Museum of Art, New York
The use of assistants and specialists, for instance, by Rubens, constitutes at most a very limited exception. Rubens ran multiple workshops employing many painters to produce his work. Each painting was minutely specified by Reubens, who prepared the drawings and executed key sections, and the assistants position was entirely subordinate to him, but the process was one of collaboration among unequals, rather than a case of the nominal artist specifying a work that could be fully executed by an arbitrary skilled workman.
For instance, the Piccirilli Brothers studio in the Bronx, NY, which covered a city block. The firm contracted carving for the majority of the prominent American sculptors of the day, and carved many of the most famous sculptures by late Nineteenth and early Twentieth Century New York sculptors,including Daniel Chester French's most famous works, Edward Clark Potter's Lions at the NY Public Library.
Although he occasionally made full-sized plaster models for planning purposes[Wittkower 91].
Neoplatonism comes up frequently in the context of Renaissance sculpture, and particularly with reference to Michelangelo. Renaissance Neoplatonism is a fusion of several ancient derivatives of the teachings of Plato (c.429-c.347 BCE) which had developed and persisted since the Fourth Century BCE. In 25 words or less, Plato taught that the material world we experience is only a transitory, imperfect approximation of Forms, the immaterial abstractions that are the immutable highest reality.

In a few more words, The Allegory of the Cave, given in The Republic, compares reality to flickering shadows on the wall of a dim cave, and Forms to that unseen thing behind us, that casts the shadows we see, but which itself can only be inferred by our ruder natures.

The Middle Platonist identification of the Forms with a single divinity accorded well with Christian theology, which subsequently incorporated a large dose of Neoplatonism when Saint Augustine systematized Christian theology in the Fourth Century CE. During the Middle Ages, the original texts were lost in the West, as was Greek itself as a scholarly language, and were almost entirely unknown until the reintroduction of Plato in Florence, in 1438. The reintroduction of Plato initiated an epochal resurgence of interest ancient Greek philosophy and art. Western thought, at the time inseparable from theology, was revolutionized by the wholesale re-introduction of fresh streams of Greek philosophy and culture.

Renaissance sculptors venerated and emulated the sculpture of the ancient world, but Classical period sculptors would have been mystified by the Renaissance aesthetic. The still-persisting Western tradition of executing representational sculpture in bare, exposed stone originated in the Renaissance, not in the ancient world. To ancient sculptors, Renaissance work would have appeared strangely unfinished; the more exuberant Classical tradition elaborately polychromed most stone sculpture, and often heavily decorated it with accessories of bronze, gold, semi-precious stone, and other materials.

In the Classical Period, the painters of sculpture were as highly regarded and sought after as the sculptors themselves[Richter 70]. Also, because the stone was intended to be painted, the ancients also routinely assembled marble sculpture from multiple pieces, a practice that horrified Michelangelo

Michelangelo said: "In every block of marble I see a statue as plain as though it stood before me, shaped and perfect in attitude and action. I have only to hew away the rough walls that imprison the lovely apparition to reveal it to the other eyes as mine see it."
Leon Battista Alberti(1404-1472) describes a measuring machine for the mechanical transfer of a model to stone. Alberti's machine produced measurements in the form of a radial angle from a fixed line, a distance along the radius, and a vertical distance to the measured point. The system and machine has the virtue of being capable of enlargement and reduction, by adjusting the scale on the target machine [Alberti 72]
No single person could produce more than a small fraction of Bernini's sculptural output unaided, and sculpture was only one of his many activities. Bernini also directed the art policy of the Papacy, was an master architect, a composer, a playwright, a prolific designer of theatrical stage sets, and an inventor of theatrical machinery.
Born 1847, died 1921.
Regardless of the merits of a single frontal viewpoint, Hildebrand's understanding of how Classical sculptors actually worked is no longer tenable. It has been well estblished that Archaic Greek sculptors consistently worked from four sides of the block, and that this mode of carving apparently continued to be the norm throughout the Classical period. The back-to-front procedure advocated by Hldebrand ironically came to be used primarily during the Hellenistic period, when compositions departed from the Classical spirit, becoming more complex, and indirect carving became a standard practice.
A real woman's head is 1/2 the width of her shoulders, while Mary's is more like 1/3.
That so many took this path at all may have been an accident of history; In the closing years of the century, in France, Rodin became effectively a one-man alternative to mid-Century Classicism. In England, many of sculptors who formed the core of the New Sculpture movement were taught by Jules Dalou, who had been a prominent practitioner of the highly naturalistic style in France, until, in 1871, he was forced into exile in England for eight years, to avoid being jailed for political reasons. Dalou convinced his friend, the emminent realist Edouard Lantieri, to go with him, which to some extent abandoned the field to Rodin during the his critical early years.
The combination of corset, wasp-waist, bustle, and no bra is quintessentially Victorian.
Antonio Canova Cupid and Psyche, plaster, 1794, Metropolitan Museum of Art, New York (left).
Antonio Canova Cupid and Psyche, plaster, 1794, Metropolitan Museum of Art, New York (left) Detail of right arm.
Davide Quayola, who usually goes by his last name alone, is an Italian artist who lives and works in London. He is not primarily a sculptor, let alone a traditional sculptor of stone. His work is more conceptual in nature, more often employing video and multimedia, and explores the relationship between information, the real, and the artificial, and frequently deals with the nature of originality and ideas in a digital context.
To do this, a long drill bit is used in place of the smooth pointer. After all but the last 1/8 inch of stone is chiselled away, the precision hole can be drilled using the pointer itself, without removing the frame from the work piece.