The wreck U Pezzo, excavated within the Saint Florent Gulf in northern
Corsica was identified as the pink, Saint Etienne, a merchant ship which
sank on January 31, 1769. In order to determine the composition of
organic materials used to coat the hull or to waterproof different parts
of the pink, a study of several samples, using molecular biomarker and
carbon isotopic analysis, was initiated. The results revealed that the
remarkable yellow coat, covering the outside planks of the ship's bottom
under the water line, is composed of sulfur, tallow (of ox and not of
cetacean origin) and black pitch which corresponds to a mixture called
``couroi'' or ``stuff'. Onboard ropes had been submitted to a tarring
treatment with pitch. Hairs mixed with pitch were identified in samples
collected between the two layers of the hull or under the sheathing
planking. The study also provides a key model for weathering of pitch,
as different degrees of degradation were found between the surface and
the heart of several samples. Accordingly, molecular parameters for
alteration were proposed. Furthermore novel mixed esters between
terpenic and diterpenic alcohols and the free major fatty acids
(C(14:0), C(16:0), C(18:0)) were detected in the yellow coat. (C) 2009
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