Romans Had a Branded Caulk Called Zopissa and a 2,200-Year-Old Service Log Just Surfaced in Croatia

Two thousand two hundred years ago, somewhere in the Adriatic, a Roman cargo ship sank near the small Croatian island of Ilovik. It sat under four meters of water until 2016, when divers found it. This week, a team of archaeologists published the part of the story that nobody expected to recover: the ship’s maintenance log, written in pollen, beeswax, and a brand-name caulk that Pliny the Elder wrote about by name.

The ship is called Ilovik-Paržine 1. The discovery, published April 24 in Frontiers in Plant Science, is not about gold, amphorae, or a tragic captain. It is about caulk. Specifically, the goo Romans used to keep their ships from sinking, and how that goo, scraped from the hull and run through a mass spectrometer, reveals four to five distinct repair sessions across both shores of the Adriatic. It is, essentially, the world’s oldest service history, and it tells you exactly where the ship had been getting its oil changes.

The caulk had a brand name and Pliny the Elder reviewed it

The substance is called zopissa. Pine tar, beeswax, mixed and heated until it could be brushed onto a hull. Pliny the Elder describes it in his Naturalis Historia, written around 77 AD, as a known commercial product. The Greeks formulated it. The Romans bought it. And until last week, archaeologists had textual references but no physical sample they could analyze at the molecular level.

Of the ten coating samples scraped from the wreck, one came back as zopissa. The rest were pure pine pitch, applied on its own, which is the cheaper option. So the ship was using a mix: premium goo where it mattered, generic where it did not. This is the same logic anyone with a car uses today. Synthetic oil for the engine, whatever is on sale for the windshield washer fluid. The Romans were doing it 22 centuries ago, on a wooden boat, with bee products.

Pollen as a service log

Here is the part that genuinely sounds like science fiction. When the caulk was applied, it was hot and sticky. Pollen blowing through whatever shipyard the work was being done in landed on the hull and got fossilized inside the resin. Each repair session trapped a different pollen signature, depending on what was flowering nearby and what the local vegetation looked like.

The team found pollen from holly oak and olive trees (Mediterranean coast), alder and ash (wetlands), and even fir and beech (mountainous interior). That is not one location. That is a tour. The ship was being patched up at multiple ports across the Adriatic over its working life, and each port left its botanical fingerprint frozen in the goo. Stack the layers and you get a route map. It is the closest thing to a GPS tracker that an ancient archaeologist will ever recover.

This is why we love a good buried object that refuses to stay buried. We recently wrote about a 1,000-year-old Anglo-Saxon ring pulled out of a Lincolnshire field with runes that nobody can read, and the first robot in cinema turned up in a potato farmer’s trunk in Michigan after being lost for 128 years. Stuff comes back. The trick is knowing what to ask it.

What the molecular analysis actually proved

The methodology is the genuine breakthrough. Previous studies on ancient hulls usually picked one substance and one dating technique. The Frontiers paper combined molecular chemistry (gas chromatography-mass spectrometry, to identify the exact compounds) with palynology (pollen analysis, to identify origin). Two parallel lines of evidence, cross-referenced.

The findings:

• The ship was almost certainly built near Brundisium, modern Brindisi in Puglia. Heel of the boot. A Roman shipyard with strong Greek-colony contact, which explains why a Greek formula like zopissa ended up on a Roman hull.
• It underwent four to five repair batches before it sank. That is a long working life for a wooden cargo ship.
• Repairs happened on both sides of the Adriatic. The ship was a regional workhorse, hauling between Italy and the Dalmatian coast.
• The repair coatings were chemically distinct from the original build coating, which means later sailors were not just slapping pitch on. They were following procedure.

Why this is more interesting than gold

Most archaeological news that breaks through to general audiences involves gold, mummies, or violence. Roman shipwrecks usually get headlines for the cargo: amphorae of wine, statues, occasionally a chest of coins. The Ilovik-Paržine 1 cargo is not the story. The hull is the story. The maintenance work is the story.

This is what makes the find unusual. We rarely get to see boring daily life from the ancient world. Most of what survives is monumental: temples, inscriptions, tombs, treasure. The everyday infrastructure (the dockyard worker scraping old caulk off a hull, the supplier mixing beeswax into pine tar, the harbormaster logging a repair) almost never makes it into the archaeological record. Wood rots. Pitch hardens. Pollen gets crushed. The fact that we now have a near-complete chemical record of a working cargo ship’s middle age is, structurally, more rare than another gold hoard.

The Romans had brand names. We forget that.

Zopissa was a product. It had a name, a recipe, and presumably a market. Pliny references it the way a modern textbook would reference a specific industrial sealant: this is what serious operators use, this is the formulation, this is what it does. There were also lower-grade alternatives (plain pine pitch) and the Ilovik wreck shows both being used on the same hull at different points. That is not improvisation. That is procurement.

The Roman world ran on supply chains that look very modern when you squint at them. Specialized regional products, standardized cargo vessels, established service ports, and a paper trail that, in this case, was written in beeswax. Empires run on logistics. The interesting parts are almost always the unglamorous ones.

What happens next

The team is now applying the same combined approach to other Mediterranean wrecks. If the method scales, we will eventually have something close to a regional shipping atlas: hull coatings traced to specific shipyards, pollen tracked to specific harbors, repair routes drawn across centuries.

This is the slow, undramatic version of archaeology that quietly changes how we picture the past. No new pharaoh, no curse, no buried treasure. Just chemistry, pollen, and a 2,200-year-old Roman shipping company finally being asked the right question. (Also, a reminder that the oldest things on Earth are usually weirder than we expect, and they tend to be hiding inside something nobody bothered to look at.)

The Ilovik wreck has been on the seafloor since the Roman Republic was still a republic. The pine trees were the same species. Beekeepers were collecting wax from the same wild colonies. And someone, in a shipyard near Brindisi, was heating pine resin and stirring in beeswax with a wooden paddle, because that is how you keep a boat from sinking. We are still, fundamentally, that civilization. We just stopped calling the caulk by name.