Mary Rose tar identified

Press, 25 July 1985, Page 12

Mary Rose tar identified

British scientists have identified the origin of large quantities of tar and pitch that were recovered with the wreck of King Henry VIII’s flagship, the Mary Rose. The raising of the famous wooden ship off the south coast of England in 1982 provided a rich source of well-preserved Tudor relics. Apart from the tar and pitch in barrels and used as waterproof coatings on anchor cables, decks, and the outer timbers of the ship, items recovered included clothing, surgical instruments, and bows and arrows. Three members of the organic chemistry unit at Bristol University in south-west England, joined the many scientists working on the relics in order to discover not only the origin of the tars and pitches but also whether they were vegetable or mineral based. Chemical analysis offered a possible solution. Samples of tars and

pitches were supplied by the Mary Rose Trust and research began under the supervision of Professor Geoffrey Eglinton. Infrared spectrophotometry (1.R.) was used to obtain information on the gross chemical composition which provided a careful comparison of the Mary Rose tars and several modern tars and pitches. The I.R. “fingerprints” for all the Mary Rose tars and pitches were similar and very different from those recorded for petroleum bitumens and for coal tars. Although there was some similarity to peat tar, by far the most striking resemblance was to present-day commercial pine wood tar, known as Stockholm Tar, which is still used to waterproof ships’ timbers. Further detailed molecular investigations were carried out using computerised gas chromato-graphic-mass spectrometric analyses. These showed that the

Mary Rose tars and pitches contained precisely the same diterpenoid compounds as did Stockholm Tar. “Indeed, the similarity was so striking that it seems likely that they were manufactured in a similar manner,” said Professor Eglinton. “Historically, trade between England and Russia in such commodities as tar was known to have been established in the 1500 s and the Mary Rose tars may have originated from Baltic Russia in this way,” he said. This year a final year student from the organic geochemistry unit carried out a detailed analysis of the cargo of tar carried by an Etruscan ship which sank off Giglio, Italy, about 600 B.C. This also proved to be of pine tar origin, very similar chemically to the Mary Rose material and the modern Stockholm Tar.