‘I found Rome a city of brick and left it a city of marble.’  Caesar Augustus (r. 27 BC – 14 AD)

Modern historians have suggested that the transformation of the ancient city at the hands of its first emperor was somewhat exaggerated; but what Augustus had set in motion was only a start, and within fifty years of his death, Pliny the Elder (d. AD 79), was lamenting his countrymen’s obsession with polished stones and gems, going so far as to describe it as ‘the leading folly of the day’.  His criticism, recorded in the Naturalis Historia, went unheeded.  

As the empire expanded, marbles and semi-precious hard-stones were imported from all around the Mediterranean, and a large centralised industry grew up to service the trade.  In the city itself a skilled workforce evolved that was capable of creating massive architectural projects, sophisticated inlaid floors and walls, and virtuoso hardstone ornaments and cameos.  Similar developments on a smaller scale happened across the empire, allowing Rome to impose its cultural stamp wherever it governed.  After the passage of two millennia the evidence can still be seen; not only in archaeological sites and museums throughout Europe, North Africa and the near East, but  in the many palaces, churches and public buildings where antique columns, pediments and artefacts have been recycled and put to new use, or simply placed on display to bear witness to the city’s glorious past. 

When the Emperor Constantine moved the capital of the empire to Byzantium in the fourth century A.D., he took his artists and craftsmen with him.  Imperial wealth became focused on the newly named-city of Constantinople, to the detriment of Rome.  To give symbolic continuity to his rule, many architectural reminders – columns, pediments, friezes, entire buildings – were shipped east and reassembled.

So began the practice of despoiling and recycling the fabric of the ancient city, a practice which accelerated after the sack of Rome in 410 A.D., and continued throughout the Middle Ages and beyond.  For over a thousand years, Ancient Rome was mined for stone and marble artefacts, sometimes used whole (as in the case of columns), more often broken up and refashioned.   The skills of cutting, carving and inlaying polychromatic marble and semi-precious hardstones, although still alive in Byzantium, were largely lost to Western Europe.

Did scagliola exist in Antiquity? 

Several commentators on scagliola maintain that the technique was known to the ancient world.  There is no physical or documentary evidence to support this, and to make the case the term ‘scagliola’ must be stretched to include all forms of polished plaster, at which point it loses its meaning.

There are other plaster-based techniques (such as stucco lustro and Venetian plastering) which are appropriate for describing the polished finishes used by Egyptians, Greeks and Romans; but they involve the trowel-based application of lime plasters mixed with marble dust, and differ significantly from true scagliola.

• • • Scagliola is made from gypsum plaster, not lime; the former sets quickly through a chemical reaction with water, the latter slowly, through drying and exposure to air.
    • Pigments are added to the scagliola plaster during a complicated mixing process. This allows for a variety of techniques to incorporate complex veining and figuring, which is then present throughout the thickness of the scagliola layer.
    • Scagliola is not spread thinly with a trowel, but pressed and pounded into moulds or onto a prepared background, in pre-set slices or sheets, usually between 6 – 12mm. thick.
    • Scagliola is allowed to set completely before levelling and polishing commences, using abrasive methods similar to those for polishing marble. At the start of the process the surface is cut back hard to reveal the figuring.  (This is impossible with painted or frescoed work, where there is no depth of pigment).  

Gypsum plasters have been found in Egyptian burial chambers, where they were used to cover and protect walls, statues and wooden sarcophagi.  The smooth surface obtained was used to paint on, but there is no evidence of attempts to imitate marble.   The Minoans and Greeks employed a lime based plaster in a similar way to protect and give a smooth surface to porous stonework and sculpture, and this was sometimes polished to a brilliant white finish.  It too was essentially a coating process, and although the plaster was polished, the technique was far removed from scagliola with its ability to produce a range of multi-coloured marbles with complex veining and figuring.

At the end of the Republican era the architect and writer Vitruvius (active 46-30 BC) described in detail the methods used by Greek plasterers working in Rome to produce hard stucco wall coatings.  The aim was to obtain a durable polished surface using a top-coat of slaked lime and marble dust.  This was either left white, or coloured with pigments applied while it was still wet, in what was clearly a fresco technique. 

In the following century Pliny the Elder noted in his Natural History that shavings of selenite were scattered around the Circus Maximus during the games to give a special lustre to the proceedings.   It may be this reference to selenite which has led to claims that the walls of the Circus Maximus were lined with white scagliola.  But there is no mention of the selenite being fired to make gypsum plaster and subsequently artificial marble; it was simply scattered on the ground in its raw, sparkly state ‘to produce an agreeable whiteness.’

The finishes achieved with these ancient plastering techniques could produce a marble-like shine, perhaps even the appearance of a marbled surface.  The aim behind scagliola is much more ambitious; it seeks to imitate marble itself in three dimensional form, and to be so convincing that it can be substituted for the real thing.  Neither Vitruvius nor Pliny made any reference to anything resembling scagliola (even though Pliny wrote a whole chapter on Specular Stone, i.e. selenite).   Had such a technique existed, it would not have escaped their attention. 

Perhaps with such a well-established and thriving stone industry in and around Rome, there was insufficient stimulus to develop an artificial marble of the complexity of scagliola; such conditions would not appear until the end of the sixteenth century.