Sulfur, acid and iron in the Vasa
After the rainy summer in 2000 the Vasa's chief conservator Ingrid Hall-Roth noticed a large number of acidic salt outbreaks on the hull of the Vasa. Synchrotron x-ray radiation helped our team of collaborating chemists to discover the origin and extent of the problems; an unexpected accumulation of reduced sulfur compounds oxidizing to sulfuric acid in the humid wood. The concern for the Vasa's future preservation has led to the research project "Save the Vasa", led by the National Maritime Museums of Sweden, where we together with several other groups seek new or improved conservation procedures.
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| Photo: Hans Hammarskjöld for the Vasa Museum |
Research is a rare privilege, when the results are of so great interest to so many, nationally and internationally. We gratefully acknowledge the Knut and Alice Wallenberg Foundation and the Carl Trygger’s Foundation, for responding promptly to the need to investigate the growing problems of the Vasa, and at an early stage provided financial support. Stanford Synchrotron Radiation Laboratory, SSRL, supported by the Department of Energy, Office of Basic Energy Sciences, USA, did after scientific evaluation allocate beam time for the very special investigations with synchrotron x-ray radiation, which revealed the cause of the problems. We wish to thank Professor Britt Hedman, Professor Keith O. Hodgson and Dr. Patric Frank at SSRL and Stanford University for their foresight and support. Akzo Nobel Rexolin AB has generously produced and donated the special complex-forming agents that we are testing for iron extraction. Many more have made important contributions. This work relies on the insight and support of the Vasa´s Conservation Council and the Vasa’s chief curators Ingrid Hall-Roth and Birgitta Håfors, curator Lovisa Dal and Leif Malmberg, Head of the ship unit. Special thanks are due to curator Bo Lundvall, conservation technician Ove Olsen and ship builder Ossi Gröndahl for expertly made core sampling of the Vasa´s hull and many invaluable discussions.
More detailed descriptions of our investigations can be found in the booklet: The Vasa's New Battle; Sulphur, Acid and Iron, M. Sandström, Y. Fors, I. Persson, Vasastudies No. 19, 2003, 80 p. (available from the Vasa Museum or from the authors).
A highlight of the synchrotron reasearch at Stanford, USA describes our investigations on the net: Can Sulfur Spectroscopy Save the 17th Century Warship Vasa? M. Sandström, F. Jalilehvand, I. Persson, U. Gelius and P. Frank, SSRL Science Highlight, Feb 2002.
Below is our group at Structural Chemistry, Stockholm University:
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| Yvonne Fors Ph.D. student, SU, examines salts in the Vasa's hold (Photo Björn Larsson Ask) | Magnus Sandström Professor, SU, examining the poulticies for neutralisation of acid in the Vasa's hold | Emiliana Damian Ph.D. student, SU, spectroscopic and diffraction studies |
Other coworkers from the start are:
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| Farideh Jalilehvand, Ass. Professor, University of Calgary, Canada, at Gustav V's dry dock, Beckholmen, Stockholm's harbour, where the Vasa was brought after salvage | Ingmar Persson, Professor at SLU, Uppsala, bringing EDMA solution to the Beckholmen laboratory | Ulrik Gelius, Professor, Uppsala University, and the ESCA instrument he has constructed |