Ancient Roman wreck reveals how sailors waterproofed ships using pine tar and beeswax

Analysis of a 2,200-year-old Roman shipwreck off Croatia shows its hull was coated with pine tar, and in one section with a pine-tar-and-beeswax mix, while trapped pollen identifies the environments where repairs were made.

A team of archaeologists and chemists studied the 2,200-year-old Roman vessel Ilovik-Paržine 1, recovered off the Croatian coast, and discovered that its hull was protected with two types of organic coating: a traditional pine-tar pitch and a mixture of pine-tar and beeswax, a formula known to Greek shipbuilders as zopissa. By applying mass-spectrometry and palynology to ten coating samples, they traced the botanical origins of the pollen trapped in the sticky pitch, linking it to Mediterranean forests, shrublands, riverbanks and mountainous regions of the north-eastern Adriatic.

The pollen record suggests the ship underwent four to five separate coating applications, implying repairs were performed at different ports, possibly including its construction site at Brundisium in Italy and later locations along the Adriatic coast. The research, published in Frontiers in Materials, underscores the importance of organic waterproofing agents in ancient shipbuilding and demonstrates how such materials can serve as environmental fingerprints of past maritime practices. Lead author Armelle Charrié emphasized that these findings provide rare insight into the technical know-how and regional variations of Roman naval engineering.