Friday, September 30, 2005


Sulfurous shipwreck


Stanford University
September 28, 2005

A conservationist works on Henry VIII's warship, the Mary Rose. The ship wreaked havoc on the French navy for 34 years until she was wrecked in 1545. Salvaged from the sea in 1982, she now rests in the Mary Rose Museum in Portsmouth, England.

Pieces of her helm recently traveled to the Stanford Synchrotron Radiation Laboratory (SSRL) at the Stanford Linear Accelerator Center, and the European Synchrotron Radiation Facility in Grenoble, France, where intense X-rays pierced the wood to analyze the sulfur and iron within.

Led by University of Stockholm Professor Magnus Sandström, researchers had studied another historical treasure, the Swedish warship Vasa, at SSRL in a similar way in 2001 (see

This time, Sandström's team is also using a newer technique—they've scanned a small X-ray beam over the oak timbers to map where the different elements reside. Exposed to the oxygen in air, the iron from corroded iron bolts in the ship catalyzes the oxidation of sulfur in the timbers into sulfuric acid, which could slowly degrade the wood until its stability is lost.

The ship is in no immediate danger, however, because the acid gets washed away during conservation. A spray treatment replaces the water in the degraded wood with waxy polyethylene glycol, so the wood does not shrink or crack as it dries out.

The researchers suggest that long-term preservation requires chemical treatments to remove or stabilize the remaining iron and sulfur compounds, and reducing humidity and access to oxygen. Photo courtesy of The Mary Rose Trust.


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