The characterization of paints and waterproofing materials from the shipwrecks found at the archaeological site of the Etruscan and Roman harbour of Pisa (Italy)

This work presents the results of a diagnostic survey on the shipwrecks from the archaeological site of the ancient harbour of San Rossore (Pisa, Italy). The original waterproofing caulking and painting materials were characterized by Fourier transform infrared spectroscopy (FTIR). gas chromatography - mass spectrometry (GC-MS), energy-dispersive X-ray micro-analysis (EDX) and X-ray diffraction (XRD). The major constituents of the waterproofing aid caulking materials detected on the planks were tricyclic abietanes showing a high degree of aromatization. These compounds are indicative of a pitch obtained from the wood of trees of the Pinaceae family. The analysis of the organic components of the paint samples revealed diterpenoid acids characteristic of Pinaceae resins together with linear long-chain alcohols and fatty acids, highlighting the presence of beeswax. Noticeably, the characteristic odd carbon number alkanes that are normally present in beeswax were not detected. The EDX and XRD analyses showed that hematite, calcite, cerussite and kaolinite were employed as pigments to paint the ships' halls.