How the plaster casts of Pompeii captured the final moments of AD 79

In 1860, Italian archaeologist Giuseppe Fiorelli was appointed as director of excavations at Pompeii under King Victor Emmanuel II. 

He began reorganised the dig site to focus more on systematic archaeology rather than treasure hunting.

Before his reforms, excavators often tunnelled into walls and removed frescoes or statues for private collections, which had damaged the site significantly.

However, under his supervision, he introduced a detailed grid system to divide the city into regiones, insulae, and numbered doorways: a method later expanded into the nine regiones, which archaeologists still use today when they record finds.

During his early excavations, he discovered that there were voids in the compacted volcanic ash that retained the shape of human and animal bodies, which had formed when organic matter decomposed over centuries.

Into these cavities, he poured a mixture of plaster of Paris and water, allowed it to set, and then uncovered the results as he carefully chipped away the ash that surrounded them.

As a result, the casts preserved the victims’ postures, folds of clothing, and even facial expressions at the moment of death, though the heat generated as the plaster set sometimes damaged bones inside the cavities. 

The conditions for these voids were set during the eruption of Mount Vesuvius in AD 79.

Pliny the Younger had described the events of that day in letters he wrote to the Roman historian Tacitus.

According to him, in the early afternoon of the traditional date of 24 August, a towering column of ash and pumice rose from the volcano and began to fall on Pompeii.

It eventually covered the city in layers several metres thick. In the streets, many residents tried to flee, but the pumice that piled up made movement nearly impossible.

Under the strain of the ash, buildings collapsed, which trapped people inside, and others died in the open as the air became unbreathable.

Later in the day, pyroclastic surges, which were clouds of superheated gas, ash, and rock that moved very quickly, swept into the city and killed those who had survived the earlier fall.

In the aftermath, very fine ash encased bodies exactly where they fell, which created airtight conditions that preserved their outlines for centuries. 

At first, Fiorelli appears to have concentrated on the casts of human victims instead of the animals, and one of the earliest recorded casts was interpreted as a woman and child, though such identifications were uncertain and remain unconfirmed.

Over time, he also created casts of animals, such as dogs and mules, which revealed as much about daily life in the city as the human figures did.

Among the most famous examples is a chained dog, long associated with the House of Vesonius Primus, though the exact findspot is uncertain due to imprecise 19th-century records.

Its body was twisted in a desperate attempt to escape. In several casts, people lay face down as if they were asleep, individuals curled into defensive positions, and limbs twisted in apparent agony.

In some examples, the detail included the imprint of sandals, the weave of fabric, or jewellery still in place at the time of death. 

Over the following decades, the technique became a key feature of archaeological work at Pompeii and was refined to improve their preservation.

From the 1980s onwards, conservators experimented with modern materials such as epoxy resin, which could capture finer details and preserve any bones that remained within the void.

Resin, though used only in a few cases due to cost and preservation concerns, made some casts more transparent, and this transparency allowed researchers to examine skeletal remains in a way that did not damage them.

In certain cases, forensic tests such as CT scanning revealed age, sex, health conditions, healed injuries, and even possible causes of death, while isotope analysis, conducted on skeletal material rather than the casts themselves, shed light on diet and where they came from. 

In many places across Pompeii, archaeologists uncovered plaster casts in private homes and public buildings, as well as in streets and garden areas.

The House of the Cryptoporticus contained several individuals who appeared to have taken shelter together.

Likewise, in the Garden of the Fugitives, excavations in 1961 uncovered thirteen people, with men, women, and children among them, who lay close together in positions that suggested a final attempt to escape through the city gates.

During Fiorelli’s time in charge and in the years that followed, the casts were put on public display, sometimes sent abroad for exhibitions, and became a main attraction for visitors who wanted a real connection to the events of AD 79.

For some scholars, the display of the dead raised ethical questions, since they preserved clothing styles, personal items, and even the physical build of Roman citizens in the first century.

Their influence reached literature and art, and even inspired works such as Edward Bulwer-Lytton’s The Last Days of Pompeii. 

Today, archaeologists continue to use Fiorelli’s idea, but they place greater emphasis on preservation and non-invasive study.

With improvements in imaging technology and conservation science, researchers can recover more information, which reduces the risk to fragile remains.