For as long as people have traveled by sea, ships have needed protection from water, salt, microorganisms, and marine animals such as worms. Yet until the mid-20th century, researchers paid relatively little attention to the non-wood materials used in ancient shipbuilding. Waterproofing materials in particular remain understudied.
A new study published in Frontiers in Materials is helping fill that gap. Researchers in France and Croatia analyzed the protective coating on the Roman Republic shipwreck Ilovik-Paržine 1, which sank about 2,200 years ago off the coast of what is now Croatia. "In archaeology, little attention is paid to organic waterproofing materials.
Yet they are essential for navigation at sea or on rivers and are true witnesses of past naval technologies," said first author Dr. Armelle Charrié, an archaeometrist at the Laboratory of Mass Spectrometry of Interactions and Systems in Strasbourg. "Studying the coatings, we found two different kinds on this vessel: one made of pine tar, also called pitch, and the other of a mixture of pine tar and beeswax.
Analysis of pollen in the coating made it possible to identify the plant taxa present in the immediate environment during the construction or repairs of the ship." The wreck was discovered in 2016, and both the vessel and its cargo have been investigated several times since then. This study is the first to combine molecular and pollen analysis to identify the ship's coatings and reconstruct the vegetation present when those materials were produced and applied to the hull. The research was carried out through a collaboration between the Department for Underwater Archaeology of the Croatian Conservation Institute and the 'ADRIBOATS' program of the Centre Camille Jullian at Aix-Marseille University in France.
"Some regions throughout the Adriatic have particular characteristics that led local populations to develop a specific shipbuilding style," said Charrié. "Only studies like ours offer an overview of these traditions which bear witness to genuine know-how and diverse traditions." To investigate the coatings, the researchers performed structural, molecular, and pollen analyses. They used methods including mass spectrometry, which can identify and measure unknown substances within complex organic mixtures.
The team analyzed 10 coating samples to determine the biological origins of the natural materials used on the vessel. Molecular fingerprinting revealed compounds associated with pine trees, showing that every sample was dominated by heated coniferous resin or coniferous tar, also called pitch. One sample, however, contained a different formulation made from beeswax and tar.
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