Roman manufacturing

Chapter 8 in 'Ancient Textiles, Modern Science II'.

The dyeing kettles in Pompeii were made from lead. Given how fragile lead is, this was anomalous from an engineering perspective - the kettles had to withstand high temperature and the weight of water to allow dyeing, which lead is unable to do. This was confirmed when finding evidence of 'lead creep' in the surviving kettles.

A mordant is the 'chemical glue' that binds a dye to a material, allowing dyeing. Once mordanted a material should not be affected by the metal a dyeing kettle has been manufactured from. This highlights further the anomaly of manufacturing kettles from lead.

A simulation of mordant and dyeing in metal kettles accessible to dyers in Pompeii was undertaken. This discovered that each metal interfered chemically with the mordanting process, the dyeing process and, when attempted sequentially, with the mordanting and dyeing process. The greatest effect was during dyeing. It was discovered that the only metal to not have a negative effect on the dye chemistry was lead, the 'neutral kettle'. Oxidised lead was found more beneficial than lead.

Prior to this study it had been thought that mordanted material would be unaffected by the dyeing kettle. This experiment showed that the material can be affected at any stage of the process and that the dyers in Pompeii had chosen lead, despite its physical disadvantages, due to its chemical properties. These were entirely new findings.

Chapter 3 in 'Ancient Textiles, Modern Science II'.

Reporting the discovery of a weaving tablet, how it came to be identified after excavation, reflecting on how many weaving tablets may already be archived without identification, then suggesting a way in which future finds may be made more accessible to aid identification.

Before this study, the understanding of the size and scale of the dyeing industry of Pompeii was based entirely on a theoretical understanding of dyeing imposed on a single superficial survey of remains. The operation and capabilities of the apparatus, and the influence of workshop layout
and location were unknown. This study used experimental archaeology to reappraise the apparatus, undertake a fresh survey and develop a new understanding of the industry. This foundation allowed exploration of unappreciated factors, such as the choice of construction materials. A full-scale replica of the dyeing apparatus from Pompeii was constructed and used to replicate mordant dyeing. This revealed the dyeing cycle time and temperatures reached, and showed the types and quantities of consumables used including fuel and water. A new survey of dyeing apparatus in Pompeii was undertaken. Two designs of apparatus were found – flued and unflued. The replica was modified to replicate the second design. The experiment diverged from archaeology to retain its validity, to discover the effect of the flue. The apparatus was replicated digitally through Finite Element Analysis to discover the failure time and process of the construction materials. Using lead in industrial equipment is so impractical the data did not exist before this study. It was the first time FEA had been used for an archaeological artefact of more than one material or to replicate heating. From this, the survey and the apparatus operation, the annual output of each apparatus, workshop and the industry overall was calculated, then compared with Pompeii’s population size to allow scale.

Presented 22nd September 2018 at TRACamp, Vindolanda.

The poster provides an overview of bone manufacture during Republic in Rome. Bone working had an important role in the manufacturing scenario, endowing objects with multiple values, from a strict functional use in entertainment, luxury and cosmetics to symbolic purposes in everyday life and funerary practices. Bone elements were carefully selected from butchery waste and underwent several processing stages: after an initial preparation which included splitting and softening, the element was roughly shaped prior to sustaining the final finishing. While finished objects might provide data on typological seriation and, in turn, chronology, waste from processing yield significant clues onto the working operations involved or the tools and methods employed. As for the Republican period, little evidence seems available so far within the urban scenario, being mainly associated with funerary contexts, whilst more abundant data have been collected in later contexts: objects from the former period would only rarely hint at local manufactures, suggesting instead products and subsequently workmanship imported from Etruria during VI-V centuries BC and from Greek Cities since IV-III BC onwards. In this respect, preliminary evidence of bone processing collected from the Palatine North-East Project could supply new data on bone manufactures in Rome during Early-to-Mid Republic.

Key words: bone, processing stages, waste, local manufacture, Etruria, Greece, Palatine